Fractal Audio Wiki - User contributions [en]

Drive block

2025-04-20T16:58:20Z

Komdosh: Delete duplicate section of OD-ONE OVERDRIVE (BOSS OD-1 Over Drive)

__TOC__
=Available on which products=

* '''Axe-Fx III''', '''VP4''': 4 blocks
* '''FM9''': 3 blocks
* '''FM3''': 2 blocks
* '''Axe-Fx II''', '''AX8''', '''FX8''': 2 blocks

=Channels or X/Y=

* '''Axe-Fx III''', '''FM9''', '''FM3''', '''VP4''': 4 channels
* '''Axe-Fx II''', '''AX8''', '''FX8''': X/Y

=Yek's Guide to the Fractal Audio Drive models=

Forum member Yek wrote and maintained a PDF guide that covers most models in detail, however work on the guide was discontinued in 2022. All information in the last edition of the guide has been checked and migrated to this Wiki page.

It required much time and effort to write the content, so <u>if you copy content, please quote the source</u>.

Click on the image below for the PDF guide, or visit <q>[https://forum.fractalaudio.com/threads/yeks-guide-to-the-fractal-audio-drive-models-updated-july-2022-axe-fx-iii-fm3-fm9.148573/ Yek's Guide to the Fractal Audio DRIVE Models]</q>.

[[image:Yeks_Drives_Guide.png|link=http://wiki.fractalaudio.com/axefx2/index.php?title=Yeks_Guide_to_the_Fractal_Audio_Drive_Models|150px]]

=About the Drive block=

'''Axe-Fx III'''

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[http://www.thegearpage.net/board/index.php?threads/axe-fx-iii.1907452/page-68#post-25886137]
The drive block in the III uses a higher oversampling ratio and double-precision filters in some places compared to the II.
</blockquote>
</blockquote>

'''Firmware 3.02 for the Axe-Fx III'''

This firmware introduced major improvements to modeling of drive pedals. Drive models based on op-amp and diode clipping topologies were been completely overhauled. This is referred to as: FASPICE. This includes all types based on the Tube Screamer circuit.

Drive models based on op-amp and diode clipping topologies have been completely overhauled.

For many types there is now a “Dry Gain” control. This parameter controls the amount of “dry” signal mixed with the “wet” (distorted) signal. For a Tube Screamer-based model this will default to 100% due to the topology. For other types this will default to 0. Values up to 200% are allowed. Note that the dry data is added before any tone controls and therefore is not exactly equivalent to a mix but rather replicates the behavior of analog circuits.

Drive types based on op-amp and diode clipping circuits now allow control over the type and quantity of diodes in the positive and negative polarity. For example, the user can select (2) 1N34A diodes for positive signal polarity and (1) red LED for negative. Experiment with the various diode types and quantities to obtain new and unique sounds.

The Basic GUI page now reflects only the controls found on the actual pedal. In cases where the actual pedal does not have any tone controls a simple Tone control is included for convenience.

The tone circuits of ALL drive types have been updated and all models have been rematched to the original pedals. [http://forum.fractalaudio.com/threads/drive-block-status.147823] [http://forum.fractalaudio.com/threads/axe-fx-iii-firmware-version-3-02-public-beta.147926/page-6#post-1749554]

The changes do not apply to the input boosts in the Amp block. [http://forum.fractalaudio.com/threads/faith-restored-in-my-axe.147281/page-3#post-1741111]

More about FASPICE:

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[http://forum.fractalaudio.com/threads/drive-block-status.147823]
New Drive block algorithm (FASPICE) implemented and working.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/faith-restored-in-my-axe.147281/#post-1740724]
I've "cracked the code" on drive pedals and figured out a way to do a SPICE simulation in real time without using gobs of CPU. It's so simple I can't believe no one ever thought of it before but none of the papers even approach anything resembling the technique. This will bring "Ares" level modeling to the Drive block.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/faith-restored-in-my-axe.147281/page-3#post-1741111]
This algorithm applies to a particular set of circuits that incorporate diodes as a nonlinear component. SPICE modeling is particularly slow when modeling diodes due to convergence issues. However the diodes in drive pedals are used in such a way that there's a trick that can be employed to dramatically decrease the amount of CPU needed to simulate the circuit.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/faith-restored-in-my-axe.147281/page-2#post-1740777]
It normally takes a lot of CPU power to do a real-time simulation. The amp block uses an entire dedicated DSP. To do even a simple distortion pedal would normally require huge amounts of CPU. But I stumbled upon a simple trick that reduces it dramatically.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/axe-fx-iii-firmware-version-3-02-public-beta.147926/#post-1749202]
See the two diodes, D1 and D2? The type and quantity of these diodes (among other things that I can't reveal) affect the tone. D1 is the "negative" diode. It conducts when the voltage is negative. D2 is the "positive" diode. It conducts when the voltage is positive. In this schematic the diodes are listed as 1N34A but in the original Distortion+ they were actually 1N270. If you select the Plus Dist model and go to the last page in the UI you'll see the type of diode is 1N270. You can change the type and quantity which will change the distortion characteristics.

1N270 and 1N34A are Germanium diodes. They have a greater reverse saturation current (Is) and, hence, a lower forward voltage for a given current. This means they clip sooner. Silicon diodes, i.e. 1N4148, 1N916, etc. have a lower Is and a greater forward voltage. LEDs have yet a greater forward voltage (smaller Is).

This new firmware has 16 diode SPICE models that I collected from various sources that you can play with. 1N914 are often substituted for 1N4148 and vice-versa but they are slightly different so I included both. The original Tube Screamer had 1S1588 which, to my ears, are much different (better) sounding than 1N914 which are used in the newer Tube Screamers.
</blockquote>
</blockquote>

For reference, Wikipedia's <q>[https://en.wikipedia.org/wiki/SPICE SPICE]</q> article says:
<blockquote>SPICE ("Simulation Program with Integrated Circuit Emphasis") is a general-purpose, open-source analog electronic circuit simulator. It is a program used in integrated circuit and board-level design to check the integrity of circuit designs and to predict circuit behavior.</blockquote>

'''Firmware 10 for the Axe-Fx III'''

* Improved Drive block. New diode modeling algorithm improves clipping accuracy especially for diodes with higher saturation currents, i.e. 1N270 and other germanium types.
* Added D9E and D18 diode models to Drive block. These are Soviet germanium diodes valued for their smooth distortion characteristics.

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-version-10-00.154850/post-1842387]
[…]
Firmware 10 uses new "FASPICE XD" modeling in the amp and drive block. It requires a bit more CPU but the accuracy is far better. I figured out a way to ensure that transcendental equations are always stiffly stable and converge in a fixed amount of time. Significantly faster and at least as accurate as trapezoidal, modified trap, gear, etc. algorithms. It dampens numerical ringing without the side-effect of damping actual circuit ringing. Once you see how it works it seems hard to believe that no one has thought of it before but I can't find a single paper or article that uses the technique. The only drawback is that frequency response is limited to about 1/2 Nyquist but since we oversample that's irrelevant.

So that's why you get the "amp feels like it's going to explode" but without the noise and artifacts.
</blockquote>
</blockquote>

The affected Drive models are: [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-version-10-00.154850/post-1842398]
<blockquote>
Rat • Super OD • T808 OD • Fat Rat • Plus Distortion • Full OD • Blues OD • Shred Distortion • M-Zone Distortion • BB Pre • Eternal Love • Esoteric ACB • Esoteric RCB • Zen Master • FAS LED-Drive • Ruckus • FAS Boost • Timothy • Tone of Kings • Heartpedal 11 • Jam Ray
</blockquote>

'''Firmware 12 for the Axe-Fx III'''

* The Drive block's EQ now supports placement pre- or post-distortion.

'''Firmware 13 for the Axe-Fx III'''

Release notes:
<blockquote>
Improved Drive block modeling. New algorithm uses a novel solution to solve the nonlinear ODE of a diode clipper with memory (i.e. a capacitor). The accuracy of the diode I-V curve is also greatly improved. This new algorithm has the accuracy of implicit iterative solutions with speed rivaling explicit solutions. CPU usage is only slightly increased vs. the previous algorithm. Note that many of the Drive models will now behave differently and presets should be auditioned. The behavior of the tone controls in some models has also changed. Of note are the Timmy models where the tone controls are now faithful to the actual pedal and decrease bass/treble when turned clockwise.

The Drive block now features a “Bass Response” control for types based on the Rat, Tube Screamer and various derivates. In some models this is duplicated on the Basic page as it is the Bass/Voice/etc. control (and renamed accordingly). This function was previously provided by the Low Cut control. The Low Cut control is now a separate control that allows adjusting the input highpass frequency. Existing presets will automatically be updated with the new default value for the Low Cut control.

Added Bias control to GUI of all Drive block models.
</blockquote>

See the [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-release-version-13-00-public-beta.164208/post-1968588 thread] for more information.

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/how-much-better-are-the-drives-compared-to-the-fm3.168483]
It solves the nonlinear ODE using a novel technique.

Personally I think it's noticeably better. I never used Drive blocks before and now I use them occasionally

They sound more "analog" and feel better. The old algorithm is the classic filter->waveshaper->filter technique. It's okay but I've long moved beyond waveshapers in amp modeling so it was time to do that in the drive block.
</blockquote>

<blockquote>
[https://www.thegearpage.net/board/index.php?threads/fm3-or-helix.2232150/post-32259119]
We completely redid the drive block using a novel technique for solving the nonlinear ODE that you get with a resistor/diode/capacitor that's used in 99% of drive pedals. It results in much improved sound and feel.
</blockquote>
</blockquote>

'''Firmware 17 for the Axe-Fx III'''

* Added 1S1588T diode SPICE model to Drive block. This is the Toshiba version of the 1S1588 and is reportedly the diode used in the “best sounding” TS-808s. The T808 OD models have been updated to use this diode. Existing presets are unchanged.
* Added “Valve Screamer VS9” and "Maxoff 808" Drive models.

The Axe-Fx III lets you set the oversampling mode for Amp and Drive blocks through the Oversampling Mode parameter in the [[Setup menu#Global Settings menu|Setup menu]]. [[Latency|Read more about latency and oversampling]]

'''Firmware 19.01 for the Axe-Fx III'''

* Added Hi Mid control to Drive block.
* Improved accuracy of “G-taper” used for tone control in some Drive models, i.e., T808, VS9, Super OD, etc. Impact on existing presets is likely negligible but any presets using Tube Screamer models and their variants should be auditioned.

'''Firmware 20.03 for the Axe-Fx III'''

* Improved Drive block.

'''Firmware 20.04 for the Axe-Fx III'''

* More Drive block improvements. Drive block now incorporates the “Chase Transform Technique” for converting analog networks to equivalent digital filters. This improves accuracy in the high frequency region.

'''Firmware 21.00 for the Axe-Fx III'''

* Improved Drive block modeling to more accurately model effects of op-amp finite open-loop gain and GBW product.

'''Firmware 23.00 for the Axe-Fx III'''

* Switching drive types is now gapless.

'''Firmware 26.01 for the Axe-Fx III'''

* Improved Drive block. Remastered most models as a result.

'''Firmware 27 for the Axe-Fx III''' [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-27-03-public-beta-3.210142/#post-2626593] [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-27-03-public-beta-3.210142/page-5#post-2627023]

* Algorithms were overhauled and improved. Models were remastered.
* Replaced fixed clip level value with data from the model itself.
* More fuzz models.

=Drive block diagram=

[[image:Drive block.png|400px]]

=Drive types per category=

==Per category==

'''Clean boosts'''
<blockquote>
Bosom Boost • Esoteric RCB • Esoteric Bass RCB • Eternal Love • FET Boost • FET Preamp • Integrated Pre • Micro Boost • SDD Preamp • Timothy
</blockquote>

'''For bass'''
<blockquote>
Blackglass 7K • Bender Fuzz • Compulsion Distortion • Esoteric Bass RCB • M-Zone • PI Fuzz
</blockquote>

'''Fuzz'''
<blockquote>
Bender Fuzz • Face Fuzz • Griddle Cake • Hard Fuzz • Master Fuzz • Octavia Distortion • PI Fuzz • Sonic Drive
</blockquote>

'''Amp-in-a-box, overdrive, distortion'''
<blockquote>
BB Pre (AT) • Blues OD • Box o’Crunch • Compulsion Distortion • DS1 Distortion • DS1 Distortion Mod • Esoteric ACB • Eternal Love • FAS Boost • FAS LED-Drive • Fat Rat • Full OD • Griddle Cake • Heartpedal 11 • Hoodoo Drive • Horizon Precision Drive • Jam Ray • Klone Chiron • Maxoff 808 • MCMLXXXI Drv • M-Zone Distortion • OD 250 • OD-One Overdrive • Plus Distortion • Rat Distortion • SDD Preamp • Shimmer Drive • Shred Distortion • Sonic Drive • Suhr Riot • Super OD • T808 Mod • T808 OD • TS9DX • Timothy • Tone of Kings • Tube Drive • Valve Screamer VS9 • Zen Master
</blockquote>

'''Metal'''
<blockquote>
M-Zone Distortion • Shred Distortion
</blockquote>

'''Other'''
<blockquote>
Bit Crusher • Mid Boost • Octavia Distortion • Tape Distortion • Treble Boost
</blockquote>

==Per clip type==

'''Diode(s), Op-amp'''
<blockquote>
BB Pre (AT) • Blues OD • Box o’Crunch • DS1 Distortion • DS1 Distortion Mod • Esoteric ACB • Esoteric RCB • Esoteric Bass RCB • Eternal Love • FAS Boost • FAS LED-Drive • Fat Rat • Full OD • Heartpedal 11 • Hoodoo Drive • Horizon Precision Drive • Jam Ray • Klone Chiron • Maxoff 808 • MCMLXXXI Drv • M-Zone Distortion • Micro Boost • OD 250 • OD-One Overdrive • Plus Distortion • Horizon Precision Drive • Rat Distortion • SDD Preamp • Shred Distortion • Sonic Drive • Suhr Riot Ge and LED/Si • Super OD • T808 Mod • T808 OD • TS9DX + • Timothy (all) • Tone of Kings • Valve Screamer VS9 • Zen Master
</blockquote>
'''FET'''
<blockquote>
Compulsion Distortion • FET Boost • FET Preamp
</blockquote>

'''Germanium'''
<blockquote>
Face Fuzz • Master Fuzz
</blockquote>

'''Silicon'''
<blockquote>
Bit Crusher • Mid Boost • PI Fuzz • Shimmer Drive • Tape Distortion • Treble Boost
</blockquote>

'''LED'''
<blockquote>
Box o’Crunch • FAS LED-Drive • Fat Rat • Suhr Riot LED • Suhr Riot LED/Si • TS9DX Hot
</blockquote>

'''Hard'''
<blockquote>
Bender Fuzz • Blackglass 7K • Hard Fuzz
</blockquote>

'''Tube'''
<blockquote>
Tube Drive
</blockquote>

'''Other'''
<blockquote>
Bosom Boost • Griddle Cake • Integrated Pre • Octave Distortion
</blockquote>

=About electronics in pedals=

Partly derived from the book <q>[https://bjooks.com/products/pedal-crush-stompbox-effects-for-creative-music-making Pedal Crush – Stompbox Effects For Creative Music Making]</q>:

A '''transistor''' is a semiconductor that amplifies the input signal and can clip the signal into distortion. It’s a compact alternative to vacuum tubes. Early germanium transistors were very unreliable. Silicon transistors provide more reliable and consistent performance.

A '''capacitator''' stores electrical energy and used for various purposes such as filtering frequencies or blocking interference.

A '''resistor''' reduces current flow and it used to control signal levels, voltage etc.

A '''diode''' is a non-amplifying semiconductor that can clip the signal into distortion. Low-gain germanium diodes have a softer and woolly sound, silicon diodes generate higher gain and hard clipping.

Besides performing as on/off lights, '''LEDs''' are diodes that can clip the signal. Every color has different characteristics.

An '''inductor''' is a coil of wire that creates a magnetic field. Used in Wah pedals to voice the effect.

An '''IC''' is an Integrated Circuit (chip) that contains transistors, resistors, capacitators etc.

An '''op-amp''', AKA <q>Operational Amplifier</q> is an IC that's capable of louder clean amplification than a transistor, using diodes to clip the signal into distortion when needed.

These YouTube videos have more information:
* [https://www.youtube.com/watch?v=EtT2gGU-6fU 1970’s Op-Amp Distortion (JHS)]
* [https://www.youtube.com/watch?v=PH2uj9bWfM4 Busting the myth of magic op-amps and diodes? (Wampler)]
* [https://www.youtube.com/watch?v=6SbwV8vx5LY What do all the parts do on a guitar pedal? (Wampler)]
* [https://www.youtube.com/watch?v=J4oO7PT_nzQ Transistors Explained (The Engineering Mindset)]
* [https://www.youtube.com/watch?v=otkW_q0_VIU Diode-Based Overdrive and Distortion Effects]

=Overdrive, distortion and fuzz=
Transistors in electronical devices amplify the signal and when they clip, they distort. The type of clipping determines how the pedal sounds and how it is categorized.

* '''Overdrive''' pedal: based on soft gradual clipping, reacts dynamically and usually is aimed at complementing or replicating the sound of a driven amplifier.
* '''Fuzz''': clips hard and aggressive and creates a buzzy sound, like something’s broken. Also, a fuzz depends on the impedance of the signal.
* '''Distortion''': covers the middle ground, leaning towards higher gain instead of overdrive.

See these references for additional information:
* Reverb's <q>[https://reverb.com/nl/news/fuzz-distorsion-et-overdrive-quelle-difference The Difference Between Fuzz, Overdrive and Distortion]</q> article.
* Pete Thorn shows <q>How To- And How NOT To- Use Overdrives And Distortions, Tone Secrets</q> in [https://www.youtube.com/watch?v=wJ8UMHODKuU Part 1] and [https://www.youtube.com/watch?v=hl669rNw5TM Part 2]
* Ultimate Guitar's <q>[https://www.ultimate-guitar.com/articles/features/brief_history_of_fuzz_effect_and_5_most_important_vintage_fuzz_pedals-94813 Brief History of Fuzz]</q> and <q>[https://www.ultimate-guitar.com/articles/features/guitar_effects_explained_this_is_the_difference_between_overdrive_distortion__fuzz-89958 This is the Difference Between Overdrive, Distortion and Fuzz]</q>
* Rhett Shull's video <q>[https://www.youtube.com/watch?v=-a5qAG1qtLs How to REALLY Use Overdrive (like the PROs)]</q>
* JHS's <q>[https://www.youtube.com/watch?v=DUUl0Y1qvuM The Origin of Fuzz]</q> and <q>[https://www.youtube.com/watch?v=XTGmfsKHcXo History Of Guitar Distortion]</q>, <q>[https://www.youtube.com/watch?v=8wVShbGe4pk Understand The Types Of Overdrive Pedals On The Market]</q> and <q>[https://www.youtube.com/watch?v=ao1aMtB6kAI How To Find the Fuzz Pedal You Need]</q> videos
* Wampler's <q>[https://www.youtube.com/watch?v=MVoPkaqRpCs OverDrive vs Distortion vs Fuzz]</q> and <q>[https://www.youtube.com/watch?v=5iM6ZdDLRP8 How do the various clipping circuits work?]</q> videos.
* Dave Hunter: <q>[https://blog.line6.com/2024/01/16/dave-hunter-the-big-buzz-origins-of-the-fuzz-box-tips-on-getting-fuzzy/ The Big Buzz – Origins of the Fuzz Box & Tips on Getting Fuzzy]</q>.

If you have Apple TV+, watch the <q>Watch the Sound</q> series episode about distortion.

=Fuzz, buffers and impedance=

Most fuzz pedals depend on a direct connection between the guitar pickup and the input of the pedal. A modeler gets in the way because its input is always buffered (inherent to the architecture), causing a modeled fuzz to react differently than the actual pedal. This is demonstrated in Wampler Pedals' video [https://www.youtube.com/watch?v=QXgBGdZTe3c&t=383s Do Fuzz Pedals sound better in a clean or dirty amp?]

To improve the emulation of such fuzz boxes, the Axe-Fx series, FM9, VP4 and FX8 allow a specific input impedance setting or an <q>Auto</q> setting. The AX8 and FM3 do not have this feature. So, when creating a fuzz-specific preset in the Axe-Fx or FX8, experiment with the Impedance parameter in the Input block. Important: the <q>Auto</q> setting only works if the Drive model is the first non-bypassed block after the Input block in the SAME row or below.

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[http://forum.fractalaudio.com/threads/fuzz-face-authenticity.105704/page-2#post-1265497]
[…]
The Fuzz in the Axe-Fx reacts as though there is a buffer in front of it (because there is). It's a limitation inherent to all modeling products. I modeled it using a nominal source resistance. I forget what I used for the source resistance but it was probably around 100K ohms. To really simulate it you would need a controller to simulate the changing output impedance of the guitar.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/fuzz-fx-blocks-and-virtual-buffering.133200/#post-1575278]
You can simulate the effect of a guitar into a Fuzz-Face using the Input-Z feature.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/drive-block-status.147823/page-2#post-1747807]
The problem is that the signal is buffered and there is no way to model the interaction of the pickups with the circuit.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/analog-drive-pedals-in-front-of-axe-iii-to-get-better-feel-who-else-is-doing-this.180332/post-2204706]
It's impossible to get a buffered device (like a multi-effect) to replicate fuzz pedals because the input impedance of a fuzz pedal is nonlinear. You can get close by using a static input resistance at the input to the device but it will never be exactly the same.

Duplicating the behavior of a fuzz pedal requires that the pedal be the first non-bypassed block following the Input 1 block and the input block impedance must be set to Auto since fuzz pedals load down the guitar’s pickups.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/this-is-why-i-use-pedals-with-axefx-why-do-you.190509/post-2365713]
The one thing no modeler will ever get perfect are fuzz pedals because of the interaction between the pickups and the pedal. The input to a modeler is necessarily buffered so that interaction is impossible to recreate.

The reason it was not included in the FM3 was cost and space.
</blockquote>

<blockquote>
[https://thegearforum.com/threads/fractal-audio-systems-mystery-product-speculation.6102/page-218#post-268933]
No digital device will do a fuzz properly because the input impedance is nonlinear. Digital devices necessarily have an input buffer. I will say our conventional, buffered, drive models are great.

</blockquote>
</blockquote>

Forum member AustinBuddy recommends setting Input Impedance to 90K in presets which have a fuzz model as the very first (non-bypassed) block. This doesn't apply to devices with fixed input impedance.

Read <q>[[Input impedance]]</q> for more information.

=Input boosts in the Amp block=

Selected Drive models, such as T808, T808 Mod, Super OD, Full OD, AC Boost, Shimmer, FAS Boost, Treble Boost, Mid Boost and RCB Boost, are also available as Input Boost types in the Amp block. They act as clean boosts, replicating the oft used <q>Drive on 0, adjust Level as desired</q> boost technique. These types do not include the clipping gain of the Drive block types, just the EQ curves.

This allows boosting an Amp model without requiring an additional Drive block, using less CPU usage. The Boost Level parameter controls the amount of boost, up to 24dB. Some types are available in the Amp block only, without a Drive block equivalent, such as Neutral, Grinder, CC Boost and Shred Boost.

Read <q>[[Amp_block#INPUT_BOOST_.2B_BOOST_TYPE_.2B_BOOST_LEVEL|Input Boost]]</q> for more information.

=Knobs and switches=

The controls on the Basic page of the Drive correspond with the knobs on the modeled devices.

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[http://forum.fractalaudio.com/threads/axe-fx-ii-quantum-rev-4-01-public-beta.119924/page-45#post-1431060]
The Tone control works the same as the modeled pedal.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/analog-drive-pedals-in-front-of-axe-iii-to-get-better-feel-who-else-is-doing-this.180332/post-2204629]
The model's controls replicate the actual pedal.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/video-boss-sd-1-vs-axe-fx-iii-super-od-sd-1.182128/post-2236354]
Note that potentiometer tolerances can be as much as +/-20%. That means the real pedal on 5 could be equivalent to the model anywhere between 4 and 6. The same applies to the Tone and Level controls. The roll off the volume test is a good way to match the gain. Roll off the volume and if the model has less gain increase the gain control and vice-versa.
</blockquote>
</blockquote>

In current firmware, the basic GUI page reflects only the controls found on the actual pedal. In cases where the actual pedal does not have any tone controls, a simple Tone control is included for convenience.

Firmware Ares 13 for the Axe-Fx:
<blockquote>The Drive block now features a “Bass Response” control for types based on the Rat, Tube Screamer and various derivates. In some models this is duplicated on the Basic page as it is the Bass/Voice/etc. control (and renamed accordingly). This function was previously provided by the Low Cut control. The Low Cut control is now a separate control that allows adjusting the input highpass frequency. Existing presets will automatically be updated with the new default value for the Low Cut control.</blockquote>

Firmware 19.01 for the Axe-Fx III added the Hi Mid control.

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/new-drive-format-question.186138/post-2302378]
It used to read -12 to +12 dB. Now it reads 0 to 10. The response is the same EXCEPT for the BB Preamp, AC Boost and RC Boost models. For those models the bass and treble response behaves the same as the real pedal. Therefore for all but the aforementioned models 0 = -12 dB, 5 = 0 dB and 10 = +12 dB.
</blockquote>
</blockquote>

=CPU usage=

Drive models use varying amounts of CPU. In the Axe-Fx II, AX8 and FX8, it is amplitude-dependent: CPU usage will rise and fluctuate when playing. This does not apply to the Axe-Fx III, FM3, FM9 and VP4.

The table below shows the CPU usage of each Drive model in the Axe-Fx III (non-Turbo) in firmware 17 for the Axe-Fx III (empty preset). The types that use the most power are diode-based.

P.S. Changing the Clip Type changing to <q>Null</q> saves a little CPU usage.

'''2% to 4%'''
<blockquote>
Bender Fuzz • Bit Crusher • Blackglass 7K • Bosom Boost • FET Boost • FET Preamp • Face Fuzz • Hard Fuzz • Integrated Pre • Master Fuzz • Micro Boost • Mid Boost • Octave Distortion • PI Fuzz • SDD Preamp • Shimmer Drive • Tape Distortion • Treble Boost • Tube Drive (all)
</blockquote>

'''8% to 9%'''
<blockquote>
BB Pre • BB Pre AT • Blues OD • Box o’Crunch • Compulsion Distortion (all) • DS1 Distortion (all) • Esoteric ACB • Esoteric RCB • Esoteric Bass RCB • Eternal Love • FAS Boost • FAS LED-Drive • Rat • Full OD • Heartpedal 11 • Hoodoo Drive • Horizon Precision Drive • Jam Ray • Klone Chiron • M-Zone Distortion • Maxoff 808 • MCMLXXXI Drv • OD 250 (all) • Plus Distortion • Rat Distortion • Shred Distortion • Sonic Drive • Suhr Riot (all) • Super OD • T808 (all) • Timothy (all) • Tone of Kings • TS9DX (all) • Valve Screamer VS9 • Zen Master
</blockquote>

=Mono input and output=

The output of the Drive block is always mono. It will also sum an incoming stereo signal to mono, so watch out for phase issues.

=Position of the EQ=

The non-graphic EQ comes after the gain (post). The Low Cut is pre-gain. High Cut is post.

The position of the graphic EQ is selectable.

=Polarity=

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/axe-fx-firmware-version-21-02-public-beta-beta-2.191173/post-2375294]
None of our effects ever invert the polarity of the signal as this will cause issues when running chains in parallel.
</blockquote>
</blockquote>

=Tips, tricks and troubleshooting=

==Factory presets==

Many factory presets contain one or more Drive blocks. Search the [[Factory presets]] page.

==Choosing and tweaking==

The sound of a drive type depends heavily on the chain, starting with the guitar and pickup. The type of amp and cabinet and amount of amp gain matter too. Fender amplifiers and Tube Screamer match so well because the pedal’s mid hump compensates for the mid-scooped frequency curve of these amplifiers. A RAT sounds better through a VOX than a Fender. A Fuzz Face sounds great through a Marshall because those amplifiers can manage the bass overload from the pedal. Some drives are designed to tighten up high gain amplifiers, some drives are meant to turn clean amps into blazing metal monsters, etc.

Depending on the Drive type, controls may do nothing or are highly sensitive. Always explore their entire range and their interaction. Examples:
* A low Drive setting with a high Level setting may sound better than just cranking Drive.
* A Bass or Treble control may need to be set to an extreme setting instead of just noon, because its acts as a “cut” control.

==Tightening the sound==

A Drive block before the Amp block, with minimal gain, will tighten the low end of dirty amp tones. It also allows turning down gain in the Amp block. This works well in particular with Tube Screamer-based Drive types.

Alternatively, use a PEQ block, set to Blocking, copying High Cut and Low Cut values from a favorite Drive type. This will apply the same coloring as the drive, without the gain and CPU usage.

Current firmware also provides Input Boost types in the Amp block itself, see above.

==Turn an Amp into a Drive==

Some manufacturers of guitar amplifiers build pedals that sound like their signature amplifiers, such as EVH 5150, Friedman BE-OD, Bogner Ecstasy Blue and Red, Bogner Uberschall, Diezel Zerrer. You can accomplish a similar thing in Fractal Audio’s modelers by changing an Amp model into a Drive model.

It's a simple procedure, simply turn off Power Amp Modeling in the amp block. Current firmware provides a switch for this and expands the inventory of drives and requires less CPU usage than a dedicated Drive block. It’s especially handy in the Axe-Fx series and FM9 with their dual amp blocks. AX8 and FM3 owners can take advantage of this as well, in combination with a real amp.

More information is in:
* The forum <q>[http://forum.fractalaudio.com/threads/want-the-mxr-5150-overdrive-pedal-you-got-it-already.106699/#post-1276274 Want the MXR 5150 Overdrive pedal? You got it already.]</q> discussion
* Leon Todd's video tutorial <q>[https://www.youtube.com/watch?v=RyMmFOVWjD4 Using Amps as Drives]</q>

This is something done with real amps too. Randy Bachman used a similar trick with his amplifiers; [https://www.guitarplayer.com/players/randy-bachman-the-guess-who-american-woman/ “The Audience Was Going Nuts. They Could Feel the Electricity Happening”: Randy Bachman Reveals How a Broken Guitar String Led to the Guess Who’s 1970 Smash “American Woman”]

<blockquote>
<blockquote>
I got the sound with my Les Paul plugged into what I called the Herzog: two Garnet amps made by [Garnet founder] Gar Gillies, with one used as a preamp.
</blockquote>
</blockquote>

==Turn a Drive into an Amp==

With some creativity, you can replace an Amp block with a Drive block. It will not sound fantastic, and it will lack dynamics, but it lets you bypass the single amp block limitation of the AX8 and FM3.
* [https://forum.fractalaudio.com/threads/the-power-of-a-drive-block-and-audio-drop-elimination.124759 Demonstration]
* [https://forum.fractalaudio.com/threads/preset-amp-cab-without-amp-cab.142395/ Simulating an amp and a cabinet, without an Amp block or Cab block]

==Add gain to high notes==

Attach Pitch (internal controller) to the Drive parameter and use Slope in the modifier menu to fine-tune. This will increase or lower gain depending on the pitch of the played note. Finetune the modifier settings for precise control.

More information is in:
* hippietim's comment in <q>[http://forum.fractalaudio.com/threads/quick-first-impressions-of-the-axe-fx-iii.136585/#post-1618726 Quick first impressions of the Axe-Fx III]</q> in the forum
* Leon Todd's <q>[https://www.youtube.com/watch?v=77EdXNqK178 5 Minute Tones - The Pitch Follower Modifier]</q> video tutorial

==Warm up or soften the Synth==

A Drive type, especially the RAT, is often used (in front of the Synth block) to warm up or often a synth tone.

==Use Tape Distortion to add vintage flavor==

The Tape Distortion, either before or after the Amp block, can add a vintage flavor to the sound.

==Distortion from the Cab block==

The [[Cab_block#Preamp | Cab block's Preamp page]] provides tools to simulate the clipping by mic preamps, channel strips and tape.

==Dynamic Distortion block==

Read <q>[[Dynamic Distortion block]]</q> for more information.

==Stacking multiple drives==

Try stacking multiple drives:
* two T808s
* two Face Fuzz models
* Octave Distortion followed by Face Fuzz
* Face Fuzz followed by Treble Booster

==Ring modulator and fuzz==

Put a tracking ring modulator before a fuzz, for example, the <q>Ring Fuzz</q> scene in the <q>[[Factory presets|BLANKENSHIP LEEDS]]</q> factory preset.

==Other drives and devices==

Note: because of ever evolving firmware, suggested settings in the links below may not be accurate anymore.

* [http://forum.fractalaudio.com/threads/emulating-the-klon-uhh-soul-food.138495 EHX Soul Food]
* [http://www.youtube.com/watch?v=V-CZtdKOUwk AA Workhorse]
* [http://forum.fractalaudio.com/threads/comp-vs-multicomp.107343 Solo Dallas Schaffer Replica pedal], [http://solodallas.com/the-schaffer-replica more information]
* [http://forum.fractalaudio.com/threads/fet-boost-drive-block-settings-for-the-ep-booster.139115 Xotic EP Booster]
* [http://forum.fractalaudio.com/threads/hendrix-style-axis-fuzz.139730 Roger Mayer Axis Fuzz]
* [http://forum.fractalaudio.com/threads/finally-copyied-the-boss-hm-2-accurately.148981/#post-1801993 Boss HM-2]
* [https://forum.fractalaudio.com/threads/drive-recipes.148316/#post-1754544 Cornish SS2]
* [https://forum.fractalaudio.com/threads/my-new-yt-utility-preset-how-much-can-you-fit-into-one-preset-download-it-and-see.164550/ JHS Superbolt]
* [https://forum.fractalaudio.com/threads/mesa-grid-slammer.182993/post-2248771 Mesa Grid Slammer]

==Using a PEQ==

A PEQ block can deliver the characteristic EQ curve of a drive pedal without its gain or sculpt the soul of an Amp model. For example, to get that ‘80s nasal hard rock tone: put a Peaking PEQ before a Plexi amp model, and add 5 to 7dB at 1000 Hz.

To approach the sound of a Klon try these settings:
* band 1 Shelving2, 150 Hz, 0.707, -12
* band 5 Shelving2, 2253 Hz, 0.707, -12, Level 1.5.

==Latency==

Read this: [[Latency]]

=Parameters=

==Mix==

Unlike other effect blocks, 0% Mix in a Drive block is not equivalent to 100% dry signal passing through ("true bypass"), because clean level can still pass through the virtual diodes (controlled by the Dry Level parameter).

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[http://forum.fractalaudio.com/threads/trouble-with-the-bb-preamp-drive-block.85418/#post-1035753]
The models let clean through even with the mix at 100%. It depends on the diodes though as to how much clean is mixed. Our models are based on the most common versions.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/bug-drive-models-in-axefx-iii.140737/#post-1667868]
The mix control in the Drive block controls the ratio of clean to dirty in the distortion stage. It's not the same as the standard mix control in the other effects.
</blockquote>
</blockquote>

The Mix parameter operates prior to any tone control. This lets you mix dry signal with the distorted signal and still maintain overall tone control. Some users lower Mix to increase transparency and attack.

Some players like to turn down the effects’s Mix level (80% or lower) to increase transparency and decrease buzziness.

==Dry Level==

Even with Mix at 100%, clean level can still pass through the virtual diodes. The Dry Level parameter in diode/opamp-based drive types (current firmware) determines the amount of clean level that passes through the diodes.

<blockquote>This parameter controls the amount of “dry” signal mixed with the “wet” (distorted) signal. For a Tube Screamer-based model this will default to 100% due to the topology. For other types this will default to 0. Values up to 200% are allowed. Note that the dry data is added before any tone controls and therefore is not exactly equivalent to a mix but rather replicates the behavior of analog circuits.

If the Dry defaults to 100 then it's a Tube Screamer derivative. Tube Screamers use a non-inverting op-amp configuration with diodes in the feedback loop. This results in a transfer function that is Y = X + f(X) where f(X) is the distortion response. IOW they mix the dry signal with a distorted signal.

[http://forum.fractalaudio.com/threads/trouble-with-the-bb-preamp-drive-block.85418/#post-1035753]
The models let clean through even with the mix at 100%. It depends on the diodes though as to how much clean is mixed. Our models are based on the most common versions.
</blockquote>
</blockquote>

==Bass Response and Low Cut==

<Blockquote>The Drive block now features a “Bass Response” control for types based on the Rat, Tube Screamer and various derivates. In some models this is duplicated on the Basic page as it is the Bass/Voice/etc. control (and renamed accordingly). This function was previously provided by the Low Cut control. The Low Cut control is now a separate control that allows adjusting the input highpass frequency. Existing presets will automatically be updated with the new default value for the Low Cut control.</Blockquote>

==Sample Rate==

Use Sample Rate Reduction to intentionally allow aliasing, for creative effects.

==Bit Reduce==

Use Bit Reduction to intentionally lower the resolution of the signal, for creative effects.

==Slew==

This probably refers to how fast the circuit can swing its output. If the signal to be amplified is too fast, the circuit will not be able to perform properly, only amplifying signals below the slew rate limit. Poor slew rate results in high frequencies not passing through the amplifier, and thereby limiting or muting high harmonics.

The Pro Co RAT is known for its poor slew rate, because of the LM308 op-amp being used. See the ElectroSmash analysis in <q>[http://www.electrosmash.com/proco-rat-analysis/pedals/distortion/pro-co-rat-distortion.html Pro Co Rat Analysi]</q>.

From Wikipedia's <q>[http://en.wikipedia.org/wiki/Slew_rate Slew Rate]</q> article:
<blockquote>
In electronic musical instruments, slew circuitry or software-generated slew functions are used deliberately to provide a portamento (also called glide or lag) feature, where an initial digital value or analog control voltage is slowly transitioned to a new value over a period of time (see interpolation).

Slew-induced distortion (SID or slew-rate induced distortion) is caused when an amplifier or transducer is required to change output (or displacement), i.e. slew rate, faster than it is able to do so without error. At such times any other signals may suffer considerable gain distortion, leading to intermodulation distortion. Transient intermodulation distortion may involve some degree of SID and/or distortion due to peak compression.
</blockquote>

From Wikipedia's <q>[https://en.wikipedia.org/wiki/Slew-induced_distortion Slew-induced distortion]</q> article:
<blockquote>
Slew-induced distortion (SID or slew-rate induced distortion) is caused when an amplifier or transducer is required to change output (or displacement), i.e. slew rate, faster than it is able to do so without error. At such times any other signals may suffer considerable gain distortion, leading to intermodulation distortion.[1] Transient intermodulation distortion may involve some degree of SID and/or distortion due to peak compression.
</blockquote>

Firmware Ares 10.01 for the Axe-Fx III:
<blockquote>
Changed Drive block Slew Limit to Slew Rate and updated default value of the models. Existing presets will be updated to the new default value upon recall. Note that the parameter now controls the slew rate and lower values equal less high frequency response at high amplitudes and vice-versa (the action is reversed from the previous firmware versions).
</blockquote>

==Graphic EQ==

The EQ can be placed either PRE or POST distortion.

The EQ is reset when changing the Drive type.

=Drive models=

Leon Todd demonstrates various Drive types in <q>[https://www.youtube.com/watch?v=ChzwxGsqxcc FM3 3.03b - New Drives, UltraRes IR's & More]</q>.

The following is a list of Fractal Audio's Drive models and the original devices on which these are based…

==77 CUSTOM OD (MXR M77 Custom Badass Modified O.D.)==

From [https://www.jimdunlop.com/mxr-custom-badass-modified-o-d/ MXR'S Custom Badass Series], a classic overdrive circuit that's been upgraded with a 100HZ control and a Bump switch for improved performance and versatility.

The sound was similar to an SD-1.

Controls: Tone, Output, 100HZ cut/boost, Gain and Bump switch (alternate EQ voicing that boosts the lows and mids, like a Tube Screamer).

[https://www.premierguitar.com/gear/mxr-custom-badass-modified-o-d-pedal-review Premier Guitar article]

[https://www.youtube.com/watch?v=RwOtEPU2GOE MXR] • [https://www.youtube.com/watch?v=jfo6uyIy44Q Audiofanzine] • [https://www.youtube.com/watch?v=1Hp-D9a9Qx8 Prymaxe] • [https://www.youtube.com/watch?v=v4jSSvN4Z4I Boss SD-1 vs MXR M77]

==BB PRE (Xotic BB preamp)==

[[file:x_BB.jpg|150px|left]]

[http://forum.fractalaudio.com/threads/fractal-audio-drive-models-bb-pre-based-on-xotic-bb-preamp.122844/ Original forum thread]

[http://xotic.us/ Xotic] is an American company known for its quality effects, such as the BB preamp, RC Booster, AC Booster, EP Booster and Robotalk, as well as its guitars and basses. Some say “BB” is an abbreviation of “Bluesbreaker”, Marshall’s vintage 2x12 combo amp, used by Eric Clapton in John Mayall’s Bluesbreakers (read more about it in [[Yeks Guide to the Fractal Audio Amp Models]]. But it doesn't sound like it is. Others say it means “Big British”. It's a diode-based pedal with a preamp gain stage that can turn a pristine clean amp into a well-behaved overdriven version. It also smoothens and compresses an already overdriven tone. While the pedal doesn’t sound like a Tube Screamer (there’s no mid-hump) and has much more gain, it is partly based on that circuit. Like all drive types, its sound depends on the amp it’s being used with. The pedal gained popularity after Andy Timmons made it his main boost pedal (before switching to MI Audio and JHS). Xotic built him a signature edition. Xotic released several versions of the pedal, with varying amounts of compression as described on [http://www.guitartoneoverload.com/2010/05/03/tube-screamer-alternative-the-bb-preamp/ Guitar Tone Overload]. The pedal is still being manufactured (version 1.5, $170) and remains a popular choice. Around 2017 Xotic reissued an earlier version of the pedal (limited edition), named BB preamp AT (AT = Andy Timmons).

<blockquote>''"The BB Preamp offers a wide variety of sounds. It’s capable of a 30dB+ clean boost with an adjustable ±15dB two band active EQ which adds a wide range of harmonic content to your ideal sound. The BB also utilizes a pre-gain stage which allows the pedal to go from a very pristine clean to a very smooth, compressed, overdriven sound."'' [https://xotic.us/effects/bb-preamp Xotic]</blockquote>

The pedal has Gain, Volume, Bass and Treble knobs. The tone controls are active, cutting or boosting up to 15dB.

Fractal Audio provides two models. One is based on the BB preamp 1.5. The other one on the BB preamp AT.

<blockquote>''"The BB is more of a clean boost it's just pushing the amp (model)."'' [https://forum.fractalaudio.com/threads/drive-block-status.147823/page-5#post-1748658 Fractal Audio]</blockquote>

At default settings into a clean amp, the models replicate an overdriven amp. A moderate Drive setting works well for the amp-in-a-box sound. Set Gain close to 0 and turn up Level to tighten an already overdriven amp or boost a clean amp. The model is featured in some factory presets, [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets search this wiki page] for “BB Pre”. If you like the character of the BB Pre model, but prefer a thicker type of sound, try the Esoteric ACB model, based on Xotic’s AC Booster pedal (now discontinued).

[https://www.youtube.com/watch?v=SiW22O914Cg Andy Timmons] • [https://www.youtube.com/watch?v=6nSgj9TLzaU J.D. Simo] • [https://www.youtube.com/watch?v=L35CpRRCfQ4 Dave Weiner] • [https://www.youtube.com/watch?v=mbNativSlqI ProGuitarShop (Strat)] • [https://www.youtube.com/watch?v=Xt8h_r_DIUk ProGuitarShop (Les Paul)] • [https://www.youtube.com/watch?v=wbJ1YRH7Z6s Sam Vilo] • [https://www.youtube.com/watch?v=wriynGui7EY Prymaxe: BB Pre] • [https://www.youtube.com/watch?v=M2cT_P0tlzI Prymaxe: BB Pre AT] • [https://www.youtube.com/watch?v=44fiFhdwmZM&t=456s Guitar Sanctuary Featuring Andy Timmons] • [https://www.youtube.com/watch?v=NsugXtkkuqA&t=431s D’Addario Sound Advice: Andy Timmons] • [https://www.youtube.com/watch?v=0bjAotoXjng Mike Hermans: BB Pre AT] • [https://www.youtube.com/watch?v=p0vIRhM_xo4 The Tone Lounge]

==BB PRE AT (Xotic BB preamp AT)==

See above.

[[file:BB-AT.jpg|160px]]

==BENDER FUZZ (Sola Sound / Vox Tone Bender)==

[[file:x_Bender.gif|150px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-bender-fuzz-based-on-sola-sound-vox-tone-bender.122897/ Original forum thread]

The classic Tone Bender fuzz originates from the ‘60s and was designed and manufactured by [http://www.macaris.co.uk/ Macari’s / Sola Sound] in the UK. The Tone Bender name was used for their series of fuzz boxes. Sola Sound and Vox Tone Benders are basically the same thing because the Sola design was licensed to JMI/Vox. Sola Sound also built the Colorsound range of effects, including the famous wah pedal, the Power Boost and the Overdriver (also provided as models) and several different versions of the Tone Bender. Jimmy Page used a Tone Bender when recording Led Zeppelin’s Whole Lotta Love, as demonstrated in the documentary [https://www.youtube.com/watch?v=zYCuqxg3RKM “It Might Get Loud“]. The Beatles, Jeff Beck in [https://www.youtube.com/watch?v=pM1qZBFiOLU The Yardbirds] and Eric Clapton have used it too.

According to [https://en.wikipedia.org/wiki/Tone_Bender Wikipedia], the first Tone Bender design (MK1) was based on the Maestro fuzz and contained three transistors. The second edition, later named MK1.5, had two transistors and was a negative feedback amplifier; the Arbiter Fuzz Face and Vox/JMI Tone Bender are based on it. The Professional MKII edition contained three transistors again; it was a MK1.5 model with an additional gain stage, and probably is the most popular and most-copied design. The MKIII (the inspiration for [https://www.fulltone.com/pedals/fuzz Fulltone’s Soul-Bender]) had an additional tone control and was followed by the MKIV. There are many clones on the market. The Colorsound “Supa” Tone Bender (1973) used silicon transistors and was based on the “Ram’s Head” Big Muff.

<blockquote>''"The Tone Bender MKI.5 is said to be the first circuit type used in any Sola Sound sand cast enclosure and the only Tone Bender made with two germanium transistors. So sonically what can you expect? The tone is a little heavier and denser when compared to that of the Professional MKII. Has some of that beefy woolliness of a good germanium Fuzz Face but still has enough cut and shove to not completely loose it in the mix. The saturation levels are lower too so works pretty neat for driving a big ballsy amplifier over the edge but never to the extent that things completely fall apart.''</blockquote>

<blockquote>''Some would say that it all about the place it holds in the world of rock’n’roll. When I demo a MKII in the shop these days I am still blown away by the sound – for me it is the epitome of great guitar tone – loads of headroom, warm fat crunch through to aggressive rock tones suitable for downtuning, then back off your volume and there are all those huge blues tones. That’s today... what it must have been like back in 1964 I can only imagine – It must have been like a spaceship landing – most people walking into Macaris back then would have only heard a fuzzbox on record – this pedal played through an old Marshall or Selmer or Vox – well, for a guitarist, it must have been life changing."'' [https://www.macaris.co.uk Macari's]</blockquote>

Many clones and replicas exist. D*A*M Stompboxes still builds authorized authentic reissues. BOSS in collaboration with Sola Sound released the Waza Craft TB-2W Tone Bender, a limited edition reissue of the MK II fuzz-pedaal, which costed over $300 when released, and goes for much higher now.

<blockquote>''“The first commercially made fuzz box to hit the UK market was the golden coloured, wedge shaped; three transistorized Gary Hurst designed Tone Bender. The Tone Bender was released in September 1965 and sold for 14 guineas, approximately £185 in today’s worth. The Tone Bender was a big hit and quickly drew big name players to a growing rank of users. The Yardbirds, The Who, The Pretty Things, The Merseybeats, The Ivy League and a rather popular band from Liverpool called the Beatles were among users of the Tone Bender. Guitar player with a Hull based band called the Rats also used this original Tone Bender as his primary fuzz sound for many years. This Guitar player was Mick Ronson who as we know went on to play lead guitar alongside a certain David Bowie. This first incarnation of the Tone Bender was only made for a relativity short time period before the design of the pedal was significantly changed.''

''Following the success of this first Tone Bender, which we will refer to as the MKI, it was clear that the design of the pedal needed to be geared towards being a more readily produced item. Early in 1966 a new improved Tone Bender arrived on the scene, this version of the Tone Bender has become known as the MKI.5. This new design was much more modern & futuristic in appearance and was also more ergonomic in its aesthetics, more space ship like in appearance than the tank like appearance of the MKI. The new improved Tone Bender enclosure was manufactured using a sand casting process and was finished in a silver/grey hammertone paint. The new Tone Bender was, like its predecessor, named only as a ‘Tone Bender’. The silk screening on the enclosure only featured the pedals name; the labelling for the controls and the input & output sockets, no company information was featured.''

''The internal construction style of the MKI.5 is of the same style that followed through into the build technique of the MKII’s. The MKI.5 utilised isolated jack sockets as to avoid ground loops, a feature used on all Tone Benders and most other quality British made effect pedals from the 1960’s. A technique unfortunately that is seldom used today. All the early Tone Benders, right up to the introduction of the MKIII, also relied heavily on the use of shielded cabling throughout. Again, a very good construction technique and yet again little seen in use today. Interesting side note, true bypass switching that is often seen as a modern feature to ‘boutique’ builders was actually first seen used in the Tone Bender MKI.''

''The earliest MKI.5 Tone Bender I seen featured two IMPEX S3-1T Germanium transistors. Possibly have been prototype unit? Commonly the MKI.5 along with a large percentage of MKII Tone Benders used the British made Mullard OC75’s. The two transistor arrangement of this type of circuit is called a voltage feedback biasing circuit. Interestingly, several fuzz boxes that first made their appearance in the year 1966 used this very same set-up. The Arbiter Fuzz Face, the Vox Tone Bender, Vox Distortion Booster and the Sola Sound made Tone Bender MKI.5. Possibly a happy coincidence? But more likely inspired by the popularity of the originator."'' [http://www.stompboxes.co.uk/ D*A*M Stompboxes]</blockquote>

[http://www.bigmuffpage.com/The_Tonebender_Timeline.html Tone Bender Timeline] • [https://en.audiofanzine.com/fuzz-pedal/editorial/articles/legends-the-history-of-the-great-fuzz-pedals.html#nbsp-a-href-fuzz-pedal-sola-sound-tone-bender-mki-sola-sound-tone-bender-1965-a The History of the Great Fuzz Pedals] • [https://www.premierguitar.com/articles/26258-face-the-fuzz-a-beginners-and-skeptics-guide-to-fuzz-pedals Premier Guitar's Face the Fuzz: A Beginner’s and Skeptic’s Guide to Fuzz Pedals] • [https://www.premierguitar.com/gear/fifty-years-of-filth-the-story-of-the-mighty-tone-bender-fuzz Premier Guitar's Fifty Years of Filth: The Story Of The Mighty Bender Fuzz] • [https://www.youtube.com/watch?v=SkzHNpQ7QCA&t=417s Rhett Shull: Macari shop story] • [https://www.ultimate-guitar.com/articles/features/brief_history_of_fuzz_effect_and_5_most_important_vintage_fuzz_pedals-94813 Brief History of Fuzz] • [https://www.tonehome.de/jmi/ ToneHome]

The most popular Tone Bender designs are simple pedals with just two knobs: Attack (amount of fuzz, Drive in the model) and Level.

<blockquote>''"The Tonebender has a lot of treble boost. If you're using it with a modern, heavy-sounding amp it will sound like cr*p. It works best with vintage, dark amps like the Class-A. It was originally designed to complement the British amps of that era which were very dark. Put it in front of the Class A model and it sounds killer.”'' [https://forum.fractalaudio.com/threads/help-with-tone-bender-model.20681/#post-347179]</blockquote>

So. far, it’s unknown which circuit has been modeled by Fractal Audio. But it doesn’t really matter: the Bender Fuzz model sounds great. While real Tone Bender pedals contain germanium transistors, the Clip Type parameter in the model is set to “Hard”, representing the circuit’s hard clipping. It is a versatile fuzz model. It can be used with a clean amp, where it will sound punchy, or with an amp with a lot of power amp distortion (e.g. Plexi), capable of filling the room and flooring the audience, making modern high-gain amps hide sheepishly in a corner. It can even be used with amps with lots of preamp gain, and with bass guitar. At high Drive settings, notes on the low E-string get spitty, like an imminent implosion to happen. Dialing in the model is as simple as putting it before or after a clean or slightly dirty Marshall amp model, turning the Drive control to the desired position, and using the guitar’s volume knob to control the amount of fuzz. Turn up Drive and Level for crushing distortion, reminiscent of Ian Thornley of Big Wreck. For a milder fuzz tone, turn down Drive. For more information about the interaction between the guitar and fuzz models, refer to the notes earlier on this page. The model is featured in some factory presets, [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets search this wiki page] for “Bender”.

[https://www.youtube.com/watch?v=NR0ST5L8-WE Sola Sound Tone Bender] • [https://www.youtube.com/watch?v=CqCwh8rCoHU Macari’s: Tonebender] • [https://www.youtube.com/watch?v=mbBAI-BuP4M Which JMI Tone Bender is Right For Me] • [https://www.youtube.com/watch?v=LUBUmO7grAg MKII Tone Bender] • [https://www.youtube.com/watch?v=70akj3s2jnk Ramble FX Twin Bender Fuzz (Pete Thorn)] • [https://www.youtube.com/watch?v=5N9CXOUnNrk Original 1973 Tone Bender] • [https://www.youtube.com/watch?v=jnSuu_QVYsM MKI Tone Bender (British Pedal Company)] • [https://www.youtube.com/watch?v=fK8hceyZa0w MKII Tone Bender (British Pedal Company)] • [https://www.youtube.com/watch?v=szeecBoEEOU MKI.5 Tone Bender (British Pedal Company)] • [https://www.youtube.com/watch?v=DY9Yquz4fxs MKIII Tone Bender (British Pedal Company)] • [https://www.youtube.com/watch?v=SkzHNpQ7QCA&t=743s The Best Fuzz Pedal I’ve Ever Played (Rhett Shull)] • [https://www.youtube.com/watch?v=f6TRH16A0pk My Most Valuable Pedals (JHS)] • [https://www.youtube.com/watch?v=XTGmfsKHcXo History Of Guitar Distortion (JHS)] • [https://www.youtube.com/watch?v=skEYdG8MTto&t=1040s 10 Rare Pedals (JHS)] • [https://www.youtube.com/watch?v=iBjXiNVTWZI&t=321s The First Guitar Effects Ever (JHS)] • [https://www.youtube.com/watch?v=ao1aMtB6kAI How to Find the Fuzz Pedal You Need (JHS)] • [https://www.youtube.com/watch?v=6-1oIJe07WM Colorsound Supa Tonebender] • [https://www.youtube.com/watch?v=PVCddgpBazM Is The BOSS Waza Tonebender Worth It? (JHS)]

==BIT CRUSHER (custom model)==

[[file:logo.jpg|150px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-bit-crusher.122924 Original forum thread]

Bit crushing is the process of intentionally downgrading audio quality, to create a warm sound or as an effect by itself. A bit-crushing pedal or software plugin often provides bit reduction and sample rate controls, and more. Fractal Audio’s Bit Crusher model is not modeled after a specific pedal, although such pedals do exist. If you don’t use the model’s bit reduction and sample rate controls, a generic drive remains.

<blockquote>''"Based on a black box we found lying in the trash outside Studio Harshclip."'' [[Owners_Manuals|Owner's Manual]]</blockquote>

The model at default settings showcases the Bit Reduce control. In fact, this control appears in every Drive type, so it’s not limited to this specific model. It lets you reduce the resolution (dynamic range) of the digital signal. This creates artifacts, a stair-stepping effect and distortion. Its value is the number of bits that will be subtracted from 24-bit full scale. For example, to create 4-bit audio, set it to 20 (default value in this model). Be aware that bit reduction will introduce background hiss and will cause the signal to drop out. The model already does this at default settings.

<blockquote>''“Samples in digital audio are recorded as integers or floating-point (real) numbers stored in computer memory. Those numbers are encoded using a series of on and off memory bits. The larger the number of bits, the more accurately a sample encodes the instantaneous volume level of a sampled audio waveform. DAWs today typically use 32-bit floating-point numbers. Early digital audio gear and video games used 8-bit integer samples or less. Roland's classic TR-909 drum machine used 6-bit integer samples. Resolution reduction intentionally reduces the number of bits used for audio samples. As the bit depth goes down, waveforms become more stair-stepped and subtle volume variations are lost. At extreme bit reduction, waveforms are reduced to clicks as a waveform jumps abruptly from low to high and back again without intervening values.”'' [https://en.wikipedia.org/wiki/Bitcrusher Wikipedia]</blockquote>

Another way to intentionally downgrade signal quality is to use the Sample Rate control. This control also appears in every Drive model. It introduces digital aliasing by reducing the sample rate from 48kHz all the way to 48Hz. This also creates digital artifacts and messes up pitch.

<blockquote>''“Digital audio is composed of a rapid series of numeric samples that encode the changing volume of an audio waveform. To accurately represent a smooth waveform, digital audio requires many samples at a high sample rate. The higher the rate, the more accurate the waveform. Higher sample rates also allow higher frequencies to be accurately encoded. DAWs today typically use 44.1 kHz or higher sample rates. Early digital gear used much lower sample rates to conserve memory for stored audio. Sample rate reduction (also called down-sampling) intentionally reduces the sample rate to degrade the quality of the audio. As the sample rate is reduced, waveforms become more coarse and high frequencies are lost. At extreme reductions, the waveform becomes metallic sounding.”'' [https://en.wikipedia.org/wiki/Bitcrusher Wikipedia]</blockquote>

[https://bjooks.com/products/pedal-crush-stompbox-effects-for-creative-music-making Pedal Crush – Stompbox Effects For Creative Music Making]

Tips:
* Run the Looper when experimenting with Bit Reduce and Sample Rate. Record a clip, set it to playback, then go wild with the controls
* Attach the Sequencer (internal controller) to a parameter in the Synth block and run it through the Bit Crusher model
* Attach an expression pedal to Sample Rate

If you like lo-fi sounds, consider these alternatives:
* Lower the low and high sliders in a GEQ block
* Use the IR of a tiny speaker cabinet
* Crank Speaker Drive in the Amp block
* Crank Drive and Saturation in the Cab block’s Preamp simulation
* Use the Ring Modulator block in non-tracking mode
* Use low-pass and high-pass filtering
* Generate pink or white noise with the Synth block

[https://www.youtube.com/watch?v=-jCwIsT0X8M Sample rates: The Higher The Better, Right?] • [https://www.youtube.com/watch?v=Shtr4eTlBC8 Battle Of The Bitcrushers] • [https://www.youtube.com/watch?v=k98vAJ5c6FI BitCrusher III] • [https://www.youtube.com/watch?v=UG8k2b9u5HU Red Panda Bitmap]

==BLACKGLASS 7K (Darkglass Microtubes B7K)==

[[file:x_B7K.png|x_B7K.png|210px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-blackglass-7k-based-on-darkglass-microtubes-b7k.132521/ Original forum thread]

Referred by its manufacturer [https://www.darkglass.com/creations/microtubes-b7k-v2/ Darkglass Electronics] as the “Black Beast”, this Scandinavian analog bass preamp and overdrive (big brother of the B3K model) is famous for its overdrive, transparency and versatility and is very popular, either as a standalone preamp or as a distortion pedal. It covers the spectrum from crystal clear powerful tones to modern crushing bass distortion.

<blockquote>''“Tone crushing overdrive and super transparent modern sound is the essence of the B7K. One of the most acclaimed Darkglass pedals in the bass community, it doesn ́t compromise the original sound of the instrument, but it enhances its presence in the mix.”'' [http://www.darkglass.com/app/uploads/2017/01/Manual-Microtubes-B7K-2017.pdf B7K Manual]</blockquote>

<blockquote>''“The Microtubes B7K takes the powerful dynamic saturation circuit of the B3K and adds a four-band equalizer and a balanced line driver for even greater versatility. Designed for both studio and live use, it will take your direct sound to a whole new level.”'' [http://www.darkglass.com/creations/microtubes-b7k Darkglass]</blockquote>

[https://www.gitarrebass.de/equipment/darkglass-electronics-microtubes-b3k-microtubes-b7k-und-microtubes-vintage-im-test/ Gitarre & Bass (German)]

Controls on the original pedal: Blend (mixes clean signal with overdriven signal), Level, Drive and four EQ knobs: Low (100Hz), Low Mids (1 kHz), Hi Mids (2.8 kHz), Treble (5 kHz). The Attack switch controls the amount of treble content to saturate and provides these options:
* Boost: emphasizes treble content
* Flat: neutral
* Cut: de-emphasizes treble content
The Grunt switch controls the amount of low frequency content to saturate before the clipping stage and provides these options:
* Fat
* Thin
* Raw

Fractal Audio’s hard-clipping model is based on the original B7K pedal, not the later Ultra and V2 editions. But because Fractal Audio includes a GEQ in every Drive block, the model already goes beyond the pedal on which it is based. Just like the real thing, Fractal Audio’s model can be used either with and without Amp and/or Cab blocks. According to Fractal Audio, the model has been created with the Attack and Grunt switches in the middle position. The Grunt switch changes the low-cut frequency. The Grunt control in the model is the same as the Low Cut control. The Attack switch controls a shelving filter on the input. Note: early versions of the model were not 100% accurate because of issues with the modeled device.

[https://www.youtube.com/watch?v=T-LTwvSu-Fo demo] • [https://www.youtube.com/watch?v=jNauO9nGm9g Darkglass] • [https://www.youtube.com/watch?v=eqJNTbJndZ8 Chris Kollias] • [https://www.youtube.com/watch?v=QpOeLqBnVSg demo] • [https://www.youtube.com/watch?v=_R6cLF4WWsE demo]

==BLUES OD (Marshall Bluesbreaker Mk1)==

[[file:x_BBmk1.png|200px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-blues-od-based-on-marshall-blues-breaker.122963/ Original forum thread]

In the ‘60s, Eric Clapton reportedly played through a very loud Marshall JTM 45 combo when recording John Mayall’s famous “Beano” album. This amp became known as the Bluesbreaker. Read more about it in the [[Yeks_Guide_to_the_Fractal_Audio_Amp_Models|Guide to the Fractal Audio Amp Models]]. In the ‘90s, Marshall released the Bluesbreaker pedal (BB), designed to replicate this sound. It was part of a series that also contained the Shredmaster and the Drivemaster pedals. It’s a light-to-moderate soft-clipping overdrive, totally different from the ubiquitous Tube Screamer sound. The Bluesbreaker pedal into a Fender enters Plexi terrritory. John Mayer ran his Bluesbreaker into a Klon.

There are Mk 1 and Mk 2 versions, with Mk 2 providing more gain. A later edition of the pedal, the Bluesbreaker BB-2 (no space in the middle of its name), is far less appreciated. Builders such as JHS ([https://www.jhspedals.info/morning-glory-v4 Morning Glory]), Wampler ([https://www.wamplerpedals.com/products/distortion-overdrive/pantheon-overdrive/ Pantheon]) and Robert Keeley have designed pedals based on the original Bluesbreaker circuit. Analog Man’s very popular [http://www.analogman.com/kingtone.htm King of Tone] is available as a separate Fractal Audio model. Read [https://www.wamplerpedals.com/blog/talking-about-gear/2018/10/the-pantheon-and-associated-pedals/ Wampler's blog]. In 2023 Marshall released a [https://marshall.com/amps/products/pedals/bluesbreaker series of reissues including the Bluesbreaker].

More information: [http://www.gitarrebass.de/workshops/marshall-blues-breaker-mk1/?utm_source=gitarrebass_weekly_nl&utm_campaign=Marshall_Blues_Breaker_Mk1_110217&utm_medium=email Gitarre & Bass (German)] • [https://www.tonehome.de/marshall-amplification/bluesbreaker/ Tonehome]

The pedal has three knobs: Gain, Tone, and Volume. Gain and Volume must be set pretty high to sufficient gain and output level from the pedal. [https://www.youtube.com/watch?v=F6POSqjjrIA John Mayer] sets all controls on the pedal to 3 o'clock, reportedly.

Fractal Audio‘s corresponding model is the Blues OD. So, to be clear: the Blues OD is NOT a model of the BOSS Blues Driver pedalFractal Audio’s BB Pre model, modeled after Xotic’s BB preamp, also references Marshall’s Bluesbreaker amp, but sounds very different. The Blues OD model can put out cutting juicy blues tones with simple adjustments. The sound varies with the type of Amp model it runs into: clean, on-the-verge-of-breakup, Fender, Marshall, etc. Set Gain between 1 and 4 o’clock for a mean blues tone. Keep Tone low because the sound gets easily piercing. The model is featured in some factory presets, [[Factory_presets|search this wiki page]] for “Blues OD”.

<blockquote>''"One of the more impressive circuits is the BluesBreaker. Whoever designed that knew what he was doing. It's unique and the designer understood the role of resistance in series with the diodes.”'' [https://forum.fractalaudio.com/threads/fractal-audio-drive-models-jam-ray-based-on-vemuram-jan-ray.148184/post-1752512 Fractal Audio]</blockquote>

[https://www.youtube.com/watch?v=d7lPo7scLF0 TheToneShack] • [https://www.youtube.com/watch?v=F6POSqjjrIA Premier Guitar's John Mayer Rig Rundown] • [https://www.youtube.com/watch?v=jvFXI446nSk The Story of Marshall Blues Breaker (ToneJunkie)] • [https://www.youtube.com/watch?v=cYHXMazyhWI Worth The Hype? (Friday Fretworks)] • [https://www.youtube.com/watch?v=s54Vrx9rTHY What Is A Blues Breaker? (JHS)] • [https://www.youtube.com/watch?v=5bk4w8rrbZk&t=535s Marshall’s Greatest Pedals (JHS)] • [https://www.youtube.com/watch?v=a6bDuYkuiIs Marshall Blues Breaker Style Overdrive Pedals: The Current Faves (That Pedal Show)] • [https://www.youtube.com/watch?v=otkW_q0_VIU&t=698s Diode-Based Overdrive and Distortion Effects] • [https://marshall.com/amps/products/pedals/bluesbreaker Marshall Vintage Reissue Pedals] • [https://www.youtube.com/watch?v=rRzsY233DNQ The Best Reissue Pedals Ever Made? (Andertons)] • [https://www.youtube.com/watch?v=rRzsY233DNQ The Best Reissue Pedals Ever Made? (Andertons)] • [https://www.youtube.com/watch?v=yBWqf25pAyk Pedal Pawn] • [https://www.youtube.com/watch?v=eVXuVhy4vGU Sweetwater] • [https://www.youtube.com/watch?v=xtTUkbRtDkM Marshall Blues Breaker or Boss Blues Driver (That Pedal Show)]

==BOSOM BOOST (Friedman Buxom Boost)==

[[file:Buxom.jpg|140px|left]]

Guitar amplification guru Dave Friedman of Friedman Amplification also builds pedals. The [https://friedmanamplification.com/shop/pedals/buxom-boost/ Buxom Boost] is his take on clean boosts. It pushes a pure and clean tone to the front of the amp.

Tone knobs on the pedal are: Mid, Bass, Treble (boosts/cuts). The EQ switch removes the EQ for more transparency. The Tight control tightens the bottom end. Boost controls the output level. With Boost at zero, the model doesn't pass signal, just like the original pedal.

When looking into clean boosts, don't overlook this model's VERY low CPU usage.

<blockquote>''"Model was verified against the actual pedal. Actual pedal doesn't have a Level control so the default is 10."'' [https://forum.fractalaudio.com/threads/buxom-boost-default-settings.195599/post-2435849 Fractal Audio]</blockquote>

[https://www.youtube.com/watch?v=tdqC52AXc4s Shawn Tubbs] • [https://www.youtube.com/watch?v=_qd7AC66JmY Pete Thorn] • [https://www.youtube.com/watch?v=tpZPemajbM4 John is just too loud] • [https://www.youtube.com/watch?v=6T1Bmy9d5Yw Tone Wars]

==BOX O'CRUNCH (MI Audio Crunch Box V1)==

[[file:x_Crunchbox.jpg|150px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-box-ocrunch-based-on-mi-audio-crunch-box-v1.164287/ Original forum thread]

Many manufacturers have tried to capture the essential sound of a tube amplifier in a pedal. John Suhr did it with the Riot pedal. Another company that succeeded, is [https://miaudio.com/ MI Audio]. Their Crunch Box Distortion pedal is one of the most popular amp-in-a-box pedals, providing the straight in-to-your-face blistering “Marshall on stereoids” sound, with prominent mids, feedback and all. It’s been said that the Crunch Box is based on [https://www.electrosmash.com/marshall-guvnor-analysis Marshall’s Guvnor (Guv’nor) pedal (1989)]. The current model is the [https://miaudio.com/Super-Crunch-Box-V2-p486048291 Super Crunch Box V2].
Like the Guvnor, the Crunch Box uses LED (light-emitting diode) clipping. Yes, those little ed lights can be used for intentional signal clipping, creating distortion. LEDs have a lot of headroom and are less fizzy and louder than other diodes. The Crunch Box itself has inspired other manufacturers (e.g. Suhr's Riot pedal, also modeled by Fractal Audio). The [https://www.jhspedals.info/current-pedals JHS Pedals Angry Charlie series], responsible for Andy Timmons' overdriven sound these days, is very similar.

<blockquote>''“I had one goal in mind with this pedal, namely to create a pedal which captures the huge crunch of a Marshall on steroids. I am VERY happy with the results. Simple and straight forward, with just gain, tone and volume. The Crunch Box has some similarities to the Tube Zone, in the sense that the design is based on a multiple clipping architecture (the signal is clipped 3 times). However, there are significant differences which make these two pedals sound quite different from each other. The Tube Zone is designed to have a very 'broad' sonic footprint. The Crunch Box on the other hand has a strong mid-presence to it, similar to the great British amps. Also, the Crunch Box has a relationship with the Blues Pro, since the tone shaping is similar to the Blues Pro. The results are really quite spectacular. In the lower gain range, the tone is very punchy and throaty. There are some great classic rock rhythm sounds to be found in there. As the gain is wound up, the Crunch Box develops a beautiful singing lead tone. The tone is shaped in a way which makes the pedal very touch sensitive, and variations in picking technique produce a very big difference on tone. Pinch harmonics are a breeze. I have put in there more gain than anyone should need, but due to the way I handled the pre-overdrive tone shaping, the pedal always stays tight and each pickup retains its character, including single coils.”'' MI Audio (Crunch Box V3 manual)</blockquote>

[https://www.gitarrebass.de/equipment/andy-timmons-sound-mi-crunch-box/ Gitarre & Bass: Andy Timmons Sound (German)]

The pedal has three knobs: Gain (model: Distortion), Tone (cuts highs), and Vol.

Fractal Audio’s model is based on the first version of the Crunch Box, now discontinued. The first version of the pedal, modeled by Fractal Audio, is not as bright as later versions, so you’ll probably want to keep Tone cranked (Tone cuts treble). Start with low Drive, Tone at 10 and Level turned up works well. [https://www.youtube.com/watch?v=POi8hUEdHJk In this video], Brett Kingman (aka Burgs) shows how to tweak the model to sound more like the brighter Crunch Box V2. The model is featured in some factory presets, [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets search this wiki page] for “Crunch”.

<blockquote>''"The model is based on a V1.”'' [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-release-version-13-00-public-beta.164208/post-1968838 Fractal Audio]</blockquote>

[https://www.youtube.com/watch?v=DQAZCv8PQlI TheToneShack] • [https://www.youtube.com/watch?v=OMJLIOSMaZM MI Audio Crunch Box (Brett Kingman)] • [https://www.youtube.com/watch?v=POi8hUEdHJk Box O' Crunch A/B'd with Crunch Box V2 (Brett Kingman)] • [https://www.youtube.com/watch?v=smZmzy8fXc4 Super Crunch Box (Brett Kingman)] • [https://www.youtube.com/watch?v=zXUhjRneV8g Super Crunch Box V2 (Brett Kingman)] • [https://www.youtube.com/watch?v=tf3pBK26jbw Haar Guitars] • [https://www.youtube.com/watch?v=2k-CzfZ8ADo Super Crunch Box vs JHS Angry Charlie] • [https://www.youtube.com/watch?v=goQ0CJNmb30 ProGuitarShop] • [https://www.youtube.com/watch?v=98KjT8TG2mE GuitarCubeChina]

==COLORTONE BOOSTER (Colorsound Power Boost)==

Based on the original pedal, with added Master control.

The original Power Boost was built and sold by Macari’s Musical Exchange in the 60s. Macari's also sold the Tone Bender, see above. The Power Boost was the predecessor to the Colorsound Overdriver and was the inspiration for some Cornish pedals.

Dave Gilmout put his Power Boost after the Big Muff Pi, to boost and EQ the fuzz sound. [https://www.gilmourish.com/?page_id=7748]

<blockquote>''"You should be able to get very close to a Cornish G2 by bypassing the tone circuit and using the High Cut as a tone control.”'' [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-27-03-public-beta.209954/#post-2623865 Fractal Audio]</blockquote>

[https://www.youtube.com/watch?v=KtsLWEDlV4c Gilmourish] • [https://www.youtube.com/watch?v=w0F11HrtmJA Pink Floyd] • [https://www.youtube.com/watch?v=tsnljfrkY4g Gilmourish] • [https://www.youtube.com/watch?v=BAaQRxHbb4M Pedal Science] • [https://www.youtube.com/watch?v=KKvFcPc8v-4 That Pedal Show] • [https://www.youtube.com/watch?v=upvkbYAZWHs demo] • [https://www.youtube.com/watch?v=RLVFIthUUuA Macari's]

==COLORTONE OD (Colorsound Overdriver)==

Based on the original pedal, with added Master control.

The Overdriver was preceded by the Colorsound Power Boost, also modeled.

[https://www.youtube.com/watch?v=kG5OC9Z036Q musictoyznetwork] • [https://www.youtube.com/watch?v=W1nf9uda8gU blondegraemy] • [https://www.youtube.com/watch?v=RLVFIthUUuA Macari's]

==COMPULSION DISTORTION HP (Fulltone OCD)==

[[file:x_OCD.jpg|240px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-compulsion-distortion-based-on-fulltone-ocd-v1.164491/ Original forum thread]

In 2005, Mike Fuller of [https://www.fulltone.com Fulltone] followed up on the success of the Full-Drive (also modeled by Fractal Audio) with the best-selling Obsessive Compulsive Drive or OCD. It’s a modern MOSFET-based overdrive / distortion with a very wide gain and dynamic range. It’s been said that the OCD is inspired by Voodoo Lab’s Overdrive pedal (also modeled), but they sound different. The OCD nails the warm sound and response of a driven tube amp convincingly (amp-in-a-box). It was an instant hit with guitar players, including pros such as Keith Urban, as well as bass players. Also, the OCD has always been affordable. Fulltone released the OCD V2 ($120) in 2017. But before that, the original OCD already had been changed seven times by Fulltone (versions 1.1 – 1.7). The OCD modeled by Fractal Audio probably might be version 1.4.

More information:<BR>
[https://www.musicradar.com/how-to/the-fx-files-fulltone-ocd Music Radar] • [https://www.guitarlessons.org/gear/pedals/fulltone/ocd/ GuitarLessons] • [https://legendarytones.com/mike-fuller-obsesses-new-version-fulltone-ocd-overdrive-introduces-ocd-v2/ Legendary Tones] • [https://www.youtube.com/watch?v=txHlJKghD0k The Story of Fulltone OCD (ToneJunkie)].

<blockquote>''“The OCD was the first pedal to use Mosfets as clipping devices. Another first was their configuration as “hard clippers connected to v-ref” instead of to ground, as was the norm. These things contribute greatly as to why the OCD has such touch-sensitivity…why they react so well when the strings are hit hard or soft, and why they sound & feel different than all other pedals out there, 90% of which are just slight tweaks of the Tube Screamer.”'' [https://www.fulltone.com/products/obsessive-compulsive-drive Fulltone]</blockquote>

<blockquote>''“The Fulltone Obsessive Compulsive Drive (OCD) is an extremely open sounding Overdrive/Distortion circuit that differs from other overdrives in that it has a good bit more Dynamic-Range...meaning the difference between picking soft or picking hard will actually yield a more natural and wider range of distortion (with less compression) than traditional diode-clipped overdrives. The OCD also creates complex overtones without changing the inherent tone of whatever amp and guitar you’re playing through, in the process lifting off that blanket other drive pedals can put on your signature sound. The OCD accomplishes its tube-like distortion through the unusual combination of overdriving its JFET opamp, and then hard-clipping with a pair of MOSFETs later on in the circuit. This topography did not exist in a pedal prior to the OCD, and the circuit works very well with a vast array of guitars and amps. Because of its large amount of available output volume, the OCD works great as a booster in front of amps to goose them into submission, as well as through Master-Volume amps to drive them much harder than most OD‘s can, but it also excels at creating its own distortion with all the chime of a Class A amp and its complex array of overtones. The OCD gives you the feeling that your amp is Cranked at even living room volume so Clean playing is more dynamic and dirty sounds still have the ringing overtones. The OCD’s can access a slew of other in-between sounds by simply turning up or down your guitar’s volume control, in fact, no other pedal “cleans up” like the OCD.”'' [https://www.fulltone.com/sites/default/files/documents/OCD_V2_manual_WEB_6-12-17.pdf Manual]</blockquote>

<blockquote>''“I think it's my favorite drive. I can see why the pedals were so popular.”'' [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-release-version-13-01.164472/post-1973229 Fractal Audio]</blockquote>

The pedal has 3 knobs and a switch:
* Drive: amount of overdrive (model: Drive)
* Tone: controls tone, noon is neutral (model: Tone)
* Volume: output level (model: Level)
* Low Peak / High Peak: the two switch positions are represented through separate models

According to the [https://www.fulltone.com/sites/default/files/documents/OCD_V2_manual_WEB_6-12-17.pdf manual], High Peak increases distortion throughout the Drive knob‘s range, delivers more volume and a slight increase in the midrange between 1-2 kHhz), for more of a “British” vibe (Vox and Marshall). Low Peak (favoured by many owners) increases accuracy to the original sound of the amp with very little coloration, which is good for clean boosting and cranked Blackface or Tweed-style ones. The switch expands the range of use of this pedal.

The Drive control covers an enormous range of gain. Low Drive and Level turned up works great as a clean boost. Turn it up and you’ll discover the potential of this model, from a mild crunch into high gain. It excels at any position, and it isn’t hard to see why the pedal is so popular. Try Drive 5, Tone 3, Level 6.5 with the LP model.

[https://www.youtube.com/watch?v=lYX8MJt4ulc That Pedal Show] • [https://www.youtube.com/watch?v=txHlJKghD0k The Story of Fulltone OCD (ToneJunkie)] • [https://www.youtube.com/watch?v=kY71ftpZwk0 Intheblues] • [https://www.youtube.com/watch?v=tZ3iumBEvCE ProGuitarShop (Les Paul)] • [https://www.youtube.com/watch?v=4diQzCr87qA ProGuitarShop (Strat)] • [https://www.youtube.com/watch?v=dDi2XEBzzH0 Haar Guitars] • [https://www.youtube.com/watch?v=EtT2gGU-6fU&t=857s 1970’s Op-Amp Distortion (JHS)] • [https://www.youtube.com/watch?v=oP6AS49pjFw Sweetwater] • [https://www.youtube.com/watch?v=oU_0Mf3CRJY Jack Fossett] • [https://www.youtube.com/watch?v=OwIQheIGjUA Audiofanzine]

==COMPULSION DISTORTION LP (Fulltone OCD)==

See above.

==DS1 DISTORTION (BOSS DS-1 Distortion)==

[[file:x_DS1.jpg|140px|left]]

Built like a tank, low price, and good performance: [https://www.boss.info/us/categories/stompboxes BOSS] always delivers. And the classic orange pedal still sells after its introduction in 1978. BOSS released a 40th anniversary edition in 2018 in black and gold colors. Unlike the SD-1 (also modeled by Fractal Audio) this is a true distortion pedal. Well-known players have used it to turn a clean amp into mayhem (Kurt Cobain in [https://www.youtube.com/watch?v=hTWKbfoikeg “Smells Like Teen Spirit”], Prince etc.), or to add more gain to an already distorted amp (Steve Vai, Joe Satriani). The op-amp distortion isn’t particularly tube-like, it has a hard edge, it’s aggressive and needs careful tweaking of gain and tone to prevent the “can of bees” sound (fizzy and harsh).

<blockquote>''“The DS-1 Distortion is a true icon in the world of guitar effects. Introduced in 1978, BOSS’s first distortion pedal defined a bold new sound, delivering hard-edged attack and smooth sustain that’s been a staple of players for generations. The DS-1 is the top-selling BOSS compact pedal ever, and its original, unchanged design continues to inspire the creation of great music everywhere. The classic DS-1 tone is behind the signature sounds of numerous rock legends, and is ready to fuel your own signature sound today. Before the DS-1, most distortion pedals produced harsh, buzzy tones and muddy sound at high gain settings. In 1978, BOSS engineers changed all that by developing a unique distortion circuit for the DS-1 that produces tight, hard-edged gain with rich harmonics while retaining the unique characteristics of different guitars and playing techniques. Hard rock, metal, and punk styles began to flourish in the ‘70s and ‘80s, and the DS-1’s tone had a defining influence on these genres. That trend has endured through multiple generations, and players around the world continue to seek out the classic DS-1 sound. From its modest three-knob interface, many different sound colors can be coaxed from the DS-1. Its pioneering two-stage circuit incorporates both transistor and op-amp gain stages. This approach is critical to the DS-1’s characteristic low-frequency fullness, which is loved by guitarists that play heavy music genres. The distortion knob offers an extremely wide range, from a mild boost for driving amps and pedals to full-throttle gain for monster rock riffs. Unlike typical tone controls that only cut highs, the DS-1’s tone circuit features an innovative design that offers far more range. Turning the knob clockwise increases highs and decreases lows, while going counter-clockwise has the opposite effect. This lets you dial in everything from tight, cutting rhythm sounds to smooth, fat lead voices. The tone control is particularly effective for maintaining low-end definition when using the DS-1 as a booster with vintage-style amps, which often sound muddy when driven with other distortion pedals.”'' [https://www.boss.info/us/products/ds-1/ BOSS]</blockquote>

<blockquote>''"This is truly a classic distortion pedal. It produces a distortion sound with a hard edge and is known to have a very low noise level compared to other distortion pedals. Many people swear that the older “Made in Japan” models sounds better than the newer “Made in Taiwan” models. The DS-1 has over the years been used by a lot of great guitar players. Steve Vai and Joe Satriani are two players who has voiced their praise over this pedal. The DS-1 is also a favorite among modifiers. Keeley, Analogman and Stinkfoot all provide their own versions of this icon among distortion makers. The design of the DS-1 has changed significantly twice throughout its lifetime. First time was around 1994 when the Toshiba TA7136AP opamp was replaced with the Rohm BA728N. In 2000 the opamp was again changed. This time it was replaced with the Mitsubishi M5223AL. Regardless of the circuit changes, the DS-1 sounds just like it did when first released back in 1978. The DS-1 has also gone through a number of cosmetical changes. The earliest version had a clear switch, silver thumb screw and the D in DS-1 placed directly underneat the t in Distortion. The clear switch disappeared around serial number 8700, the silver thumb screw at serial number 0500 while the D in DS-1 ended up under the i in Distortion around serial number 13xx00.”'' [https://bossarea.com/ds1/ Bossarea]</blockquote>

[https://www.musicradar.com/how-to/the-fx-files-boss-ds-1 MusicRadar] • [https://www.gitarrebass.de/workshops/kondensator-tausch-bei-boss-ds-1/ Gitarre&Bass: Boss DS-1 Distortion Mods] • [https://www.gitarrebass.de/workshops/boss-ds-1-keeley-clipping-mode-mod/ Gitarre&Bass: Boss DS-1 Keeley Clipping Mode Mod] • [https://www.gitarrebass.de/workshops/boss-ds-1-keeley-mod/ Gitarre&Bass: Boss DS-1 Keeley Mod] • [https://www.youtube.com/watch?v=Zg6JYTbt0d4 Boss Is Best (JHS)] • [https://www.youtube.com/watch?v=XTGmfsKHcXo History Of Guitar Distortion (JHS)] • [https://www.youtube.com/watch?v=EtT2gGU-6fU 1970’s Op-Amp Distortion (JHS)] • [https://www.electrosmash.com/boss-ds1-analysis Boss DS-1 Distortion Analysis (ElectroSmash)] • [https://www.tonehome.de/boss/ds-1-distortion/ Schematic (ToneHome)]

The DS-1 has three controls: Tone, Level and Distortion. The popular way to dial in the DS-1 is to set Distortion and Tone far below 12 o’clock and turn up the level, and use it with an already distorted amplifier.

Fractal Audio has modeled the DS-1 and provides a virtually modded version as well, based on Robert Keeley’s popular Seeing Eye (LED-clipping) and Ultra mods.

<blockquote>''"I made the model by taking the DS-1 and applying the Keeley "Seeing Eye" and "Ultra" mods.”'' [https://forum.fractalaudio.com/threads/the-new-ds1-mod-is-unbelievably-good.168264/post-2021098 Fractal Audio]</blockquote>

The model has been updated to Second Edition specs.

<blockquote>''"Some component values changed. Not a big difference."'' [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-27-03-public-beta-2.210131/#post-2626446 Fractal Audio] </blockquote>

[https://www.youtube.com/watch?v=HxAakmSg_OI BOSSChannel] • [https://www.youtube.com/watch?v=GxvwyCb5mP0 Must Have Guitar Essentials (JHS)] • [https://www.youtube.com/watch?v=hVxaqPurxb4 Nirvana Guitar Tones (Reverb)] • [https://www.youtube.com/watch?v=dXPvs0HOdfs Pete Thorn] • [https://www.youtube.com/watch?v=VZenfW-XdX0 ProGuitarShop] • [https://www.youtube.com/watch?v=6-88lrO_jcw Stop Using It Wrong!] • [https://www.youtube.com/watch?v=ouYuP_HW2so Ola Englund] • [https://www.youtube.com/watch?v=GUY2PBqKXow Kurt Cobain 1991 Nevermind Gear Guide (PMT)] • [https://www.youtube.com/watch?v=l7SM2IH_siE Is the Boss DS-1 The Best Distortion Pedal Ever? (PMT)] • [https://www.youtube.com/watch?v=YZdR_1jtyCY The Vape] • [https://www.youtube.com/watch?v=9ev_-DkMT_0 gearmanndude] • [https://www.youtube.com/watch?v=otkW_q0_VIU&t=858s Diode-Based Overdrive and Distortion Effects] • [https://www.youtube.com/watch?v=KSYijxVjs60 What Makes This Pedal Great (Wampler)] • [https://www.youtube.com/watch?v=cr0tASqUF64 Rhett Shull: This Is WAY Better Than The Tubescreamer] • [https://www.youtube.com/watch?v=QHUoHJLbHmg DS-1 Mod Shootout: Keeley Ultra vs All Seeing Eye vs Stock] • [https://www.youtube.com/watch?v=ZSeyIXJfhK4 Boss DS1W WAZA (Pete Thorn]

==DS1 DISTORTION MOD (modded BOSS DS-1 Distortion)==

See above.

==ESOTERIC ACB (Xotic AC Booster)==

[[file:x_AC.jpg|150px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-esoteric-acb-based-on-xotic-ac-booster.123002/ Original forum thread]

[http://xotic.us/ Xotic] is an American company known for its quality effects, such as the RC Booster, AC Booster, EP Booster, BB preamp and Robotalk, as well as its guitars and basses. The AC Booster (“Almost Clean”) pedal is a diode-based overdrive pedal. It produces a sweet overdrive with an uncompressed tube feel. Its sound is thicker than the BB preamp pedal / BB Pre model (see above). It lends itself very well to thicken an already overdriven rhythm or lead tone. It can also operate as an overdrive on its own. The AC Booster has been discontinued.

<blockquote>''“The Xotic AC Booster Overdrive Guitar Effects Pedal creates a warm and pleasant sound by using the finest quality parts available. The AC Booster is a natural sounding "overdrive" pedal. Not "heavy" distortion, but a sweet thick overdrive with an "open" non-compressed feel. It's capable of a 20dB+ boost with an adjustable ±15dB two band active EQ, which adds a wide range of harmonic content to your ideal sound. The super wide range gain control allows for enough gain for it to work as a distortion pedal when turned all the way up. Equipped with not only boost Gain but also Treble and Bass controls that allow you to adjust your sound anyway you like”'' [https://xotic.us/effects/ Xotic]</blockquote>

The pedal has Gain, Volume, Bass and Treble knobs. The tone controls are active, cutting or boosting up to 15dB. It doesn’t hurt to turn up Treble a little, to prevent muddiness.

The model is also available as an input boost type in the Amp block.

[https://www.youtube.com/watch?v=k0mdMJxvp00 ProGuitarShop: Strat] • [https://www.youtube.com/watch?v=7w9Y76gZXUE ProGuitarShop] • [https://www.youtube.com/watch?v=6nSgj9TLzaU J.D. Simo] • [https://www.youtube.com/watch?v=gNIQbgJPJQk Tim Pierce] • [https://www.youtube.com/watch?v=kxpGcT2Z2QU Prymaxe] • [https://www.youtube.com/watch?v=QBotJ7yHczk Living Room Gear Demos]

==ESOTERIC BASS RCB (Xotic Bass RC Booster)==

[[file:RC-Bass.jpg|200px]]

It's a version of the RC Booster (see below) designed for bass guitar.

==ESOTERIC RCB (Xotic RC Booster v1)==

[[file:x_RC.jpg|150px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-esoteric-rcb-based-on-xotic-rc-booster.123033/ Original forum thread]

[http://xotic.us/ Xotic] is an American company known for its quality effects, such as the AC Booster, RC Booster, EP Booster, BB preamp and Robotalk, as well as its guitars and basses. The RC Booster (“Really Clean”) diode-based pedal is very popular as a clean boost. Known for its transparency, it enhances the sound and harmonics of the guitar and amp, adding body. Its EQ controls lets further sculpt the tone. Many users, including pros, leave the pedal turned on all the time. It’s also used often to boost the level when switching to single-coil pickups, using the tone controls to finetune the sound. Scott Henderson has been the pedal’s main endorser and has been honored with signature editions ([http://www.gitarrebass.de/equipment/xotic-rc-booster-sh-im-test/ review in German]), which led to the development of the RC Booster v2 ($170) with a second gain channel. In 2022 a 20th Anniversary edition was released with cosmetic changes only.

<blockquote>''“The best characteristic of this booster is to have no character at all.” </blockquote>

<blockquote>''“The RC Booster offers a super transparent 20db+ clean boost and a +- 15db 2 band active EQ without ever compromising the integrity of the original TONE. It provides a solution to sound degradation, caused by long instrument cables and/or long effect chains between guitar and amp, by strengthening the original signal.”'' [http://xotic.us/ Xotic]</blockquote>

<blockquote>''“I particularly LOVE the RC Boost for single coils - Strats and Teles or P-90s or lipstick tube pickups. I usually just leave an RC Boost or Fractal drive block "on" when using them. Not a lot of drive when using Fractal version, less than 2 sometimes to emulate the clean boost of an RC, and volume around 4.5 to 5.5. One of the secrets of the amazing Doyle Bramhall II is he usually puts an RC boost pedal next to last in his signal chain, right before the wah (which is last!), and shaves just a hair off the top and bottom end using the tone controls, and then has drive and level at about 11 to 11:30 as well...also works good. When used right, the RC Boost makes your Strat or Tele or Lipstick tube pickups sound like single coil pickups but louder, approaching humbucker signal level (P90s usually have some stronger output and may not need as much help).”'' AustinBuddy</blockquote>

The pedal has Gain, Volume, Bass and Treble knobs. The tone controls are active, cutting or boosting up to 15dB.

The model is based on an original RC Booster (v1). You can argue about the need in a digital environment for a Drive block that acts as a clean boost, because there are less CPU-hungry solutions to neutrally boost signal level. But the RCB model adds a little magic of its own if you keep Gain low. The model is also available as an input boost type in the Amp block. The model is featured in some factory presets, [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets search this wiki page] for “RCB”.

[https://www.youtube.com/watch?v=dZhApZVvxpc Michael Thompson] • [https://www.youtube.com/watch?v=0Lotkb0Xciw Xotic] • [https://www.youtube.com/watch?v=ZY9dIk748FY ProGuitarShop] • [https://www.youtube.com/watch?v=MXlK3KOZ2xE ProGuitarShop: RC Booster V2] • [https://www.youtube.com/watch?v=n0Q4UbjBA1o Scott Henderson Signature Model] • [https://www.youtube.com/watch?v=QcS9SJEzcPI Scott Henderson Interview] • [https://www.youtube.com/watch?v=5VW0c9d4P1k Ryan Kiesshausser] • [https://www.youtube.com/watch?v=rZ3_GDci29k Prymaxe] • [https://www.youtube.com/watch?v=rmReDeiQk_M Andrew Cheng] • [https://www.youtube.com/watch?v=8kRNZ7oeUao shnobel] • [https://www.youtube.com/watch?v=44fiFhdwmZM&t=347s Guitar Sanctuary featuring Andy Timmons] • [https://www.youtube.com/watch?v=NsugXtkkuqA&t=310s D’Addario Sound Advice] • [https://www.youtube.com/watch?v=mGyEuAO8BfY Mike Hermans]

==ETERNAL LOVE (Lovepedal Eternity)==

[[file:x_Eternal.jpg|200px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-eternal-love-based-on-lovepedal-eternity.123069/ Original forum thread]

It seems that each day a new overdrive pedal is released to the masses, either boutique or mass-produced. Often, it's just another variation on the same old Tube Screamer circuit. Yet, some stand out and earn a permanent position in this crowded market. [http://lovepedal.com Lovepedal’s Eternity] is such a pedal. Even being within the higher price segment, it has found its way onto many pedalboards.

<blockquote>''"The Lovepedal Eternity delivers fantastic, tubey overdrive at every setting. You just can’t make this pedal sound bad. The extremely interactive controls offer you three knob options for sculpting overdrive sounds; Drive, Level (clean boost), and Glass which functions as a treble booster. Through variation of the Drive and Level knobs you can alter the mix of pedal distortion sound and your amp’s natural overdrive characteristics, giving you a myriad of tone options. Through manipulation of the Glass knob you can dial in some sweet Brian May style tones, or roll it off for some dark, warm goodness. The Love Pedal Eternity has developed a huge following and is currently played by Andy Summers of The Police and Richard Fortus of Guns N’ Roses, among others. The Lovepedal Eternity can be 3 pedals in one – Overdrive, Treble Booster and Clean booster – depending on where you set the dials. You can also blend these 3 factors. Darker tones brighter tones, etc. Unorthodox tone control. It’s a treble boost instead of a normal tone control. It is a very smooth type of OD. It can go from nothing at all to sounding like a very warm vintage overdriven tube amp or a clean flat booster or a treble booster even a tweed amp. With the treble boost all the way off, it is warmer than most tube amps. The Eternity Overdrive always stays true to what’s coming out of your guitar so you never turn into the pedal. No matter how hard you drive it. It also breaks up the harder you dig into the strings, which is priceless.”'' [http://lovepedal.com/ Lovepedal]</blockquote>

Lovepedal has released various versions of the pedal over the years and the differences aren’t always clear. It is unknown which version of the Eternity has been modeled by Fractal Audio.

The Eternity pedal has three knobs: Level, Drive and Glass (model: Tone) which sets the amount of presence. The Glass knob has a large range which makes it very versatile. With Tone cranked, the model turns into a treble booster. [https://www.youtube.com/watch?v=kPtdfjxX59U&t=417s Richard Fortus (Guns N’ Roses)] sets the knobs like this: Level 3 o‘clock, Glass 9 o’clock, Drive 12 o’clock.

The diode-based model of the Eternity noticeably has less bass and low mids than comparable pedals / models. It doesn't emphasize the mids in the same way a Tube Screamer does. This makes it more transparent, less grainy and an excellent choice to put before a clean Amp model for “edge-of-breakup” rhythm strumming, while still having enough body for single note runs. To add glassy presence to clean (and dirty) amp tones: turn down Drive low (try 0.25), turn down Tone a bit, and run it into a clean amp for a great edge-of-breakup sound, or into a dirty amp for focused overdrive. For more gain, increase Drive and Level. The model is featured in some factory presets, [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets search this wiki page] for “Eternal”.

[https://www.youtube.com/watch?v=3pjnwMZEAcM Eternity versions] • [https://www.youtube.com/watch?v=u-GCRjPfpAs ProGuitarShop] • [https://www.youtube.com/watch?v=yPh1EAL7GlA Jack Zucker] • [https://www.youtube.com/watch?v=a-1AI3RsEig Sean Michael: Kanji Eternity] • [https://www.youtube.com/watch?v=SVJ4smdHmlo Sean Michael: Eternity John F. Klaver]

==FACE FUZZ (Dallas-Arbiter Fuzz Face)==

[[file:x_Fuzzface.png|210px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-face-fuzz-based-on-dallas-arbiter-fuzz-face.123104/ Original forum thread]

Dallas-Arbiter’s Fuzz Face (1966, UK) is based on the Maestro fuzz and the Tone Bender MK1.5 fuzz with two transistors. With its smiley face shape, it’s perhaps the most famous of all fuzz boxes because Jimi Hendrix used it. Hendrix used germanium-based designs (pre 1969) at first and switched to the silicon versions (post 1969). The silicon ones produce higher and more aggressive gain. His Fuzz Face pedal [https://reverb.com/nl/news/jimi-hendrix-fuzz-face-sells-for-32,500 sold for over $40.000]! Other famous users include David Gilmour, Stevie Ray Vaughan, Pete Townsend, Eric Johnson (silicon version) and Gary Clark Jr. The Fuzz Face was the first pedal to have a true bypass switch. [http://www.jimdunlop.com/ Dunlop] now owns the rights to the [http://www.foxroxelectronics.com/The-Fuzz-Face-Reissue-Story_b_3.html Fuzz Face name] and produces [http://www.jimdunlop.com/products/electronics/dunlop-electronics various versions]. Fulltone’s [https://www.fulltone.com/products/70-pedal-bc The ’70 Pedal] is based on the silicon version. [https://www.jhspedals.info/fuzz-series-smiley JHS Pedals’ Smiley] is one of many clones.

<blockquote>''"Arbiter Electronics Ltd. first issued the Fuzz Face in 1966. Later units bear the "Dallas Arbiter", "Dallas Music Industries Ltd.", "CBS/Arbiter Ltd." or "Dunlop Manufacturing Inc." name. The earliest units used germanium transistors. Silicon transistors were used in later editions of the pedal. Silicon transistors provided for a more stable operation, but have a different, harsher sound. The electronics are contained in a circular-shaped metal housing. Ivor Arbiter "got the idea for the round shape when he one day saw a microphone stand with a cast iron base". The pedal uses two knobs, one for volume, and one for the amount of "fuzz" the pedal produces. The arrangement of controls and logo on the box suggests a smiling face. The circuit is based on the shunt-series-feedback amplifier topology - a standard in engineering text books. Sola Sound and Vox had been using the same circuit topology for some of their Tone Bender pedals earlier in 1966. Dallas Music Industries made a final run of Fuzz Faces in 1976 or 1977, shortly after they had moved to the United States. The company bought Crest Audio in the 1980s and although it was operating under that name when it reissued the Fuzz Face in the 1986, the units bore the Dallas-Arbiter name. They made about 2000 Fuzz Faces until 1990. In 1993 Dunlop Manufacturing took over production, making a variety of Fuzz Faces to this day. Several germanium and silicon models are available.”'' [https://en.wikipedia.org/wiki/Fuzz_Face Wikipedia]</blockquote>

[http://tonereport.com/blogs/lifestyle/the-history-of-the-fuzz-face The History of the Fuzz Face (Tone Report)] • [http://www.gitarrebass.de/equipment/effektiv-jimi-hendrix-teil-1-fuzz-face/ Gitarre & Bass: Jimi Hendrix: Fuzz Face (German)] • [https://www.gitarrebass.de/workshops/effektiv-arbiter-fuzz-face/ Gitarre & Bass: Arbiter Fuzz Face (German)] • [http://www.electrosmash.com/fuzz-face Fuzz Face Analysis (ElectroSmash)] • [https://en.audiofanzine.com/fuzz-pedal/editorial/articles/legends-the-history-of-the-great-fuzz-pedals.html#a-href-fuzz-pedal-dallas-arbiter-fuzz-face-originale-vintage-60-s-70-s-arbiter-fuzz-face-1966-a Legends – The History of the Great Fuzz Pedals (Audiofanzine)] • [https://www.premierguitar.com/gear/face-the-fuzz-a-beginners-and-skeptics-guide-to-fuzz-pedals Premier Guitar's Face the Fuzz] • [https://www.ultimate-guitar.com/articles/features/brief_history_of_fuzz_effect_and_5_most_important_vintage_fuzz_pedals-94813 Brief History of Fuzz]

The Fuzz Face is a simple pedal with just two knobs: Volume and Fuzz (model: Drive).

A Fuzz Face tends to sound better with a Marshall than a Fender amp etc., because Marshalls have less bass, and a Fuzz Face puts out loads of bass. any players put this fuzz before a non-master amp (i.e., Plexi), because the power amp’s distortion will soften the hard, harsh clipping of the fuzz. They crank the Fuzz and Volume knobs and use the guitar’s volume knob to get the desired amount of fuzz. Glassy clean sounds are also achievable, especially with the germanium-based version, by turning down volume on the guitar. Other tricks: follow the Fuzz Face with a Treble Booster to tame the lows or put the Octave Distortion model before the fuzz. With Fuzz maxed out, the pedal sounds like a ring modulator.

Fractal Audio’s Face Fuzz model is based on a germanium Fuzz Face. You can easily switch to the silicon version by changing the Clip Type parameter in the model. The model is featured in some factory presets, [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets search this wiki page] for “Face Fuzz”.

[https://www.youtube.com/watch?v=n8458cWMwU8 Tone Factor] • [https://www.youtube.com/watch?v=kMEXoo0pKNI Fuzz Face Shoot Out (James Santiago)] • [https://www.youtube.com/watch?v=HPJ0RbqMskA Fuzzface shootout (gearmanndude)] • [https://www.youtube.com/watch?v=18bBbNeMyhA gearmanndude] • [https://www.youtube.com/watch?v=0EqrQPbOhDo ProGuitarShop] • [https://www.youtube.com/watch?v=Qte0vvpWb2o Hendrix Fuzz Face Tips and Tricks (James Santiago)] • [https://www.youtube.com/watch?t=605&v=XTGmfsKHcXo History Of Guitar Distortion (JHS)] • [https://www.youtube.com/watch?v=iBjXiNVTWZI&t=519s The First Guitar Effects Ever (JHS)] • [https://www.youtube.com/watch?v=ao1aMtB6kAI How To Find the Fuzz Pedal You Need (JHS)] • [https://www.youtube.com/watch?v=YYDz427MxsI JJ of the T] • [https://www.youtube.com/watch?v=q507hz7HN4s Vintage Vs Modern Fuzz Face Pedals (Wampler)]

==FAS BOOST (custom model)==

[[file:logo.jpg|150px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-fas-boost.123143/ Original forum thread]

Fractal Audio provides a couple of custom models. These virtual drives have no real-life equivalents. They solely exist within Fractal Audio’s processors, implementing ideas and improvements on existing pedals. The FAS Boost model does a fine job as such. Its gain is pleasing and neutral without a mid-hump, it’s full-bodied and smooth, and a little dark. In short time, it has become a favorite among many Fractal Audio players. It works equally well with clean and dirty amp tones, not needing a lot of gain (try Drive at 3, Tone at 7). It also works well as a boost. The model is also available as an input boost type in the Amp block. It is featured in some factory presets, [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets search this wiki page] for “FAS Boost”. The model lends itself as a platform to emulate other pedals. For example, forum members have used it to recreate a Maxon overdrive. Fractal Audio’s design lets you experiment with different diode types and quantities.

<blockquote>''"It's not based on anything. It's my take on an ideal boost pedal.”'' [https://forum.fractalaudio.com/threads/fas-boost.106558/post-1276269 Fractal Audio]</blockquote>

==FAS LED-DRIVE (custom model)==

[[file:LED.png|100px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-fas-led-drive.123163/ Original forum thread]

Fractal Audio provides a couple of custom models. These virtual drives have no real-life equivalents. They solely exist within Fractal Audio’s processors, implementing ideas and improvements on existing pedals. The LED-Drive model is such a custom model. It models [https://en.wikipedia.org/wiki/Light-emitting_diode LED (light-emitting diode) clipping]. Yes, those little lights can be used for intentional signal clipping, creating distortion. LEDs have a lot of headroom and are less fizzy and louder than other diodes. This can be demonstrated by comparing the “LED” Clip Type to other types. [https://www.youtube.com/watch?v=bifKfe04TBc Video: test different clipping modes for diy pedals]. LED clipping isn’t used that often in pedals, although it seems to gain popularity. Examples: MI Audio’s Crunch Box (modeled by Fractal Audio), Pro Co's Turbo Rat, Landgraff’s L'DO, Keeley’s Psi Fuzz, modifications of the BOSS DS-1 (modeled by Fractal Audio), Ibanez TS9DX Hot (modeled by Fractal Audio), Suhr Riot (modeled by Fractal Audio), and guitar amplifiers such as Marshall’s Jubilee. The LED-Drive model sounds most pleasing when used with a dirty amp model, with Drive turned down and Tone a bit up.

==FAT RAT (modded Pro Co RAT with LED clipping)==

[[file:FATRAT.png|225px]]

Based on a Pro Co RAT, changed to LED clipping. See RAT DISTORTION below.

==FET BOOST (custom model)==

[[file:logo.jpg|150px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-fet-boost-and-a-bit-of-klon.123178/ Original forum thread]

FET is the abbreviation of Field-Effect-Transistor, a semi-conductor. FETs are used in pedals and amplifiers. For example, Dumble amplifiers have a FET input for low-gain instruments. In guitar-oriented products, MOSFET and JFET types are common.

<blockquote>''“The field-effect transistor (FET) is a transistor that uses an electric field to control the shape and hence the electrical conductivity of a channel of one type of charge carrier in a semiconductor material. FETs are also known as unipolar transistors since they involve single-carrier-type operation. The FET has several forms, but all have high input impedance. While the conductivity of a non-FET is regulated by the input current (the emitter to base current) and so has a low input impedance, a FET's conductivity is regulated by a voltage applied to a terminal (the gate) which is insulated from the device. The applied gate voltage imposes an electric field into the device, which in turn attracts or repels charge carriers to or from the region between a source terminal and a drain terminal. The density of charge carriers in turn influences the conductivity between the source and drain. (...) The most commonly used FET is the MOSFET.”'' [https://en.wikipedia.org/wiki/Field-effect_transistor Wikipedia]</blockquote>

<blockquote>''“FET’s can behave like Tubes in a properly designed circuit. They can “clip” (distort) in a pleasing way instead of being buzzy or spiky sounding (like a Transistor) and can also add a subtle Limiting to the signal which can even-out the volume making your Live and Recorded tones more pleasing to the ear."'' [https://www.fulltone.com/ Fulltone]</blockquote>

FET is available as a Clip Type in Fractal Audio’s modeling of drives, demonstrated through the FET Boost model. Note that FET Boost and FET Preamp are different Drive models. The FET Boost model is not based on a real pedal, it’s a custom model. Fractal Audio’s custom models have no real-life equivalents. They solely exist within Fractal Audio’s processors, implementing ideas and improvements on existing pedals. The FET Boost model has been in the firmware since the early days. It’s a favorite model of many players, boosting the signal going into the amp. Slamming the input of amps often results in better tone than using an overdrive. The increased amp distortion is natural, and the tone gets fatter, enhancing the characteristics of the amp instead of changing them. So why do people love this model? Well, how do you describe sound, why does person A like a certain tone, and person B doesn’t? The FET Boost is rather neutral (the tone doesn’t change much at default settings into a clean amp) but still adds “something” to the tone. To operate as a boost, use default settings and adjust Drive or Level. The FET Boost model is featured in some factory presets, [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets search this wiki page] for “FET Boost”.

<blockquote>''"A gentle, smooth clipping booster with tone controls."'' [https://wiki.fractalaudio.com/wiki/index.php?title=Owners_Manuals Owners Manual]</blockquote>

[https://www.youtube.com/watch?v=kYvaaQd8IU8 Fulltone Fat Boost 3 (ProGuitarShop)] • [https://www.youtube.com/watch?v=xn2ijKnVifA Fulltone Fat-Boost vs Fat-Boost II (Gearmanndude)]

==FET PREAMP (possibly based on the BOSS FA-1 FET Amplifier)==

[[file:x_FA1.png|135px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-fet-preamp-based-on-boss-fa-1-fet-amplifier.123270/ Original forum thread]

When this model was added to Fractal Audio’s firmware, it became known that The Edge (U2) had started using Fractal Audio gear. The Edge is known for using the [https://www.musicradar.com/news/guitars/u2-exclusive-the-edges-stage-setup-revealed-223342 BOSS FA-1]. Perhaps there’s some correlation between The Edge’s use of Fractal Audio gear and the addition of this model. But it has never been disclosed or acknowledged that this model is based on the FA-1. For this write-up, the model is assumed to be similar. Reportedly, Rory Gallagher sometimes used the FA-1 as a replacement for his Dallas Rangemaster treble booster. The rare BOSS FA-1 FET Amplifier, from the short-lived Pocket Series, is a pocket-size amp, meant to be attached to the player’s belt. It’s not a pedal and doesn’t even have an On/Off switch. It was made between 1983 and 1984. FET is an abbreviation of Field-Effect-Transistor, a semi-conductor. For more information, read the FET Boost article. It’s hard to find an original FA-1 nowadays. If you do find one, it will be expensive but there are lots of clones, including DIY. JHS manufactures its own clone, the [https://www.jhspedals.info/clover Clover].

The FA-1 is primarily used as a boost. Slamming the input of an amp often results in better tone than using an overdrive pedal. The increased amp distortion is natural and transparent, and the tone gets fatter, enhancing the characteristics of the amp instead of changing those. Alternative boosting solutions are discussed elsewhere on this page.

[https://www.manualslib.com/manual/569775/Boss-Fa-1.html#manual BOSS FA-1 manual] • [https://catalinbread.com/blogs/kulas-cabinet/boss-fa-1-fet-amplifier Catalinbread] • [https://www.tonehome.de/boss/fa-1-fet-amp/ ToneHome Schematic]

The FA-1 has these controls: Volume (model: Drive), Bass and Treble (active tone controls) and a Flat / Low Cut switch. The switch is a 6dB low cut at 200 Hz, designed to prevent feedback (“howling”) when used with acoustic instruments. Similar behavior can be achieved in the model with the Low Cut control.

The FET Preamp model, which may or may not be based on the FA-1, is not entirely neutral or clean. It adds grit and warmth to the tone and provides much more gain than the FET Boost model. Reportedly, the FET Preamp with Drive at zero sounds like the pre-amp section of the Maestro EP-3 Echoplex, sweetening and compressing the sound a little. As such, it may be an alternative to EP-3 clones such as the Xotic EP Booster and Catalinbread Epoch Pre.

The model also lends itself as a substitute for a basic clean guitar amp (model). Select the FET Preamp, turn up Tone, Treble and Bass, keep Level really low, add another drive before it (i.e. BB or Riot). It won’t sound fantastic, and dynamics will be mostly absent. This allows you to use the Fractal Audio FX8 as a preamp (perhaps connected to a separate power amp and a cabinet). On the FX8, you can even use it in combination with some EQ to simulate an amplifier as well as a cabinet, without using an Amp block and Cab block at all, [https://forum.fractalaudio.com/threads/preset-amp-cab-without-amp-cab.142395/ as demonstrated here].

The model is featured in some factory presets, [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets search this wiki page] for “FET Preamp”.

[https://www.youtube.com/watch?v=P1N-6Mbgs6s Boss fa1 Fet Amplifier rehoused by JHS] • [https://www.youtube.com/watch?v=3F_s4cqsJKI Retro Sonic Boost FA-1 (ProGuitarShop)] • [https://www.youtube.com/watch?v=qdO-RoHTDDY Boss FET Amplifier FA 1] • [https://www.youtube.com/watch?v=Evm2mvQSRH4&t=681s Why You NEED Boost Pedals (JHS)] • [https://www.youtube.com/watch?v=SVbceQGhbdM&t=182s Why You Need A Preamp (FA-1) (JHS)] • [https://www.youtube.com/watch?v=9DKf25X-DYg Boss FA-1 FET Amp demo]

==FULL OD (Fulltone Full-Drive 2)==

[[file:x_FD2.jpg|260px|left]]

[http://forum.fractalaudio.com/threads/fractal-audio-drive-models-full-od-based-on-fulltone-full-drive-2.123297/ Original forum thread]

Mike Fuller of [https://www.fulltone.com/ Fulltone] was one of the first designers of boutique pedals. He is the inventor of the 3PDT switch, allowing manufacturers to build true bypass pedals with a LED. The Full-Drive overdrive pedal (1993), and especially the ’96 Full-Drive 2 (FD2), marked the rise of his fame. The diode-based pedal is based on the Tube Screamer circuit but has evolved since then. Like the Tube Screamer, the Full-Drive can be used as a standalone overdrive or to boost an already overdriven amp. It has 3 modes: Vintage, Flat Mids and Comp-Cut. There are many versions of the Full-Drive, including smaller enclosures. The ’96 orange Full-Drive 2 is very collectable. The Full-Drive 2 V2, released in 2018 ($200), features a second channel. The Full-Drive is used by John Mayer, Robin Trower (picture) and many others.

[https://legendarytones.com/fulltone-fulldrive-2/ Legendary Tones] • [https://reverb.com/nl/news/5-killer-dual-channel-overdrives 5 Killer Dual Channel Overdrives (Reverb)] • [https://www.gitarrebass.de/heftarchiv/2014-11/fulltone-full-drive-3-overdrive-pedal Gitarre & Bass: Fulltone Full-Drive 3 (German)] • [https://www.gitarrebass.de/equipment/test-fulltone-full-drive-1-2-3/ Gitarre & Bass: Fulltone Full-Drive 1, 2, 3 (German) ]

The pedal has these controls: Volume, Tone, Overdrive, Boost (not modeled). The Tone knob acts as a Presence control. Some versions of the pedal offer additional controls, such as a Comp/Cut push-pull pot and a second drive channel. Robin Trower sets the three controls on his pedal around 3 o’clock, running into a clean-sounding Marshall.

Fractal Audio’s Full OD model is thick and dark. Set Drive low to smooth out an already overdriven amp or turn it up with a clean amp. Turn up Tone high to add presence to the sound, as with the real pedal. For an aggressive heavy sound, run it with low Drive into a high gain amp.
The Full OD model is also available as an input boost type in the Amp block. The model is featured in some factory presets, [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets search this wiki page] for “Full OD”.

<blockquote>''"The Full OD model is based on a Fulltone Fulldrive 2."'' [https://forum.fractalaudio.com/threads/ax8-drives.120062/post-1429331 Fractal Audio]</blockquote>

[https://www.youtube.com/watch?v=9ePvJ6_TTFo Full Drive 2] • [https://www.youtube.com/watch?v=7fT1a_E_ItU Fulldrive 3 vs Fulldrive 2] • [https://www.youtube.com/watch?v=scqA1G5TPDM Sound Like John Mayer By Busting The Bank (Andertons)] • [https://www.youtube.com/watch?v=uj3nwpCfZOA Robin Trower] • [https://www.youtube.com/watch?v=4p5aivFszNA FullDrive 2 vs Fractal FullOD] • [https://www.youtube.com/watch?v=XfWl7c0QbMQ Premier Guitar's Rig Rundown: Robin Trower] • [https://www.youtube.com/watch?v=skEYdG8MTto&t=259s 10 Rare Pedals (JHS)] • [https://www.youtube.com/watch?v=dRQHGigxBSw Full Drive V2 How-To] • [https://www.youtube.com/watch?v=51PP1-j5n0o Regent Sounds] • [https://www.youtube.com/watch?v=otkW_q0_VIU&t=995s Diode-Based Overdrive and Distortion Effects] • [https://www.youtube.com/watch?v=pFOD6s0IRoM Bad Monkey vs Full-Drive (JHS)]

==GAUSS DRIVE (Mesa Flux-Drive)==

[[file:flux-drive.jpg|155px|left]]

[https://www.mesaboogie.com/nl-NL/Pedal/FP.FLUXDRIVE/FP-FLUXDRIVE Mesa states]: "The overdrive pedal for those who want more of all the best things from an overdrive! It has more liquid gain and enhanced sustain that easily feeds into rich harmonic overtones making it incredibly addictive and inspiring to play, whether into a clean amp channel or especially to enhance a crunch or higher gain channel! It also offers a more complete tone-shaping network with individual Treble and Bass controls. This architecture makes the FLUX-DRIVE a more complete preamp with added versatility beyond that of most overdrive pedals."

Controls: Level, Gain, Bass, Treble.

[https://www.youtube.com/watch?v=3UoP7Fr6ft8 Harry Maes] • [https://www.youtube.com/watch?v=2cIK78uWTOA N Stuff Music]

==GRIDDLE CAKE (Crowther Hot Cake)==

[[file:HotCake.jpg|155px|left]]

Paul Crowther from New Zealand has been making the Hot Cake overdrive pedal in various versions since 1976. Mark Knopfler and Neil Finn are famous users. Depending on the version, the player can switch between Normal / Bluesberry mode, and guitar / bass mode. The V2 version adds external switches for extended low frequencies (XLF switch) and smoother overdrive (Cream+ switch). The Kometcake was a version for Komet amplifiers. Like the Klon and many overdrive pedals, the Hot Cake sounds best as an overdrive when used with an amplifier that’s already breaking up. It’s fat but doesn’t turn the sound into a compressed mess. It matches especially well with mid-heavy VOX-type amplifiers.

The pedal has these controls: Level, Presence, Drive, and a XLF switch which extends low frequencies (for bass and extended range guitars). The XLF function can be replicated by turning the Bass Response knob in the model fully clockwise.

With Drive and Presence set low, the pedal operates as a clean boost. Turn up Drive and it’s an overdrive, without drifting away from the amplifier’s core sound. Crank Drive, and it enters fuzz territory.

It doesn’t have a treble cut circuit. The Presence control bumps the 800Hz EQ band. With Presence turned counterclockwise, mids are flat, making it a great fit with mid-heavy VOX-type amplifiers. Older Hot Cake versions have a fixed switch instead of variable Presence.

[https://www.youtube.com/watch?v=rclnK4C35Ec David Fisher] • [https://www.youtube.com/watch?v=6JzKHYNViAg Brett Kingman: Double Hotcake] • [https://www.youtube.com/watch?v=5bHsXf79PFA Leon Todd: I regretted selling this pedal] • [https://www.youtube.com/watch?v=1itTPt6V1Z4 The SuperFunAwesomeHappyTime Pedal Show] • [https://www.youtube.com/watch?v=FXuRpPXRBa4 Prymaxe] • [https://www.youtube.com/watch?v=Jp4qBny30tE My new favorite overdrive pedal] • [https://www.youtube.com/watch?t=2530&v=bAwJRI46TRE Neil Finn] • [https://www.youtube.com/watch?v=I_Z5uvmhRA4 ToneFactor] • [https://www.youtube.com/watch?v=FXR7eq8QGrA Guitar Empire] • [https://www.youtube.com/watch?v=iYOVv7vomO4 Leon Todd: the new Axe-Fx III Hot Cake Model] • [https://www.youtube.com/watch?v=JYAvQpo6o5o John Cordy]

==HARD FUZZ (custom model)==

[[file:logo.jpg|150px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-hard-fuzz.123336/ Original forum thread]

This model is described in the [[Owners Manuals]] as a “hard-clipping, 60s-style fuzz”. It’s a custom model, not based on a real pedal. Fractal Audio’s custom models have no real-life equivalents. They solely exist within Fractal Audio’s processors, implementing ideas and improvements on existing pedals.
It’s certainly different from the other available fuzz models. It uses the “Hard” clip type and is very buzzy. It seems to work best with a clean Amp model. With Drive turned up high, the bass gets out of control. As always with fuzzes, use the guitar’s volume knob to control the amount of fuzz. The Hard Fuzz is featured in factory presets such as factory presets like [[Factory presets|Stereo Death Fuzz, Post Amp Fuzz and Shoegaze Fuzz]].

==HEARTPEDAL 11 (Lovepedal OD11 / Amp Eleven)==

[[file:x_Amp11.jpg|300px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-heartpedal-11-based-on-lovepedal-od11-amp-eleven.148168/ Original forum thread]

Lovepedal’s OD11 (OD Eleven) and Amp Eleven pedals feature the same type of overdrive, replicating the authentic sound of an overdriven tube amp. They won’t do over-the-top distortion, but convincingly produce organic, dynamic, and touch-sensitive overdrive, without too much tone coloring. The OD11 isn’t produced anymore, it has been integrated in the Amp Eleven pedal, with the addition of a boost section.

<blockquote>''“AMP ELEVEN, fat, organic tone of an overdriven tube amp – with separate controls for bass and tone. (...) Smooth, round, balanced, low-to-medium gain overdrive. Slight overdrive to mild distortion. Great dynamic response and open sound.”'' [http://www.lovepedal.com/pedals/amp-eleven/ Lovepedal]</blockquote>

The pedal, together with some others, has been the cause of some stir on internet forums. [https://www.youtube.com/watch?v=5Oukng0DxUY This That Pedal Show episode] demonstrates the similarities between the Timmy, Jan Ray and Amp Eleven. In this episode, it’s stated that the Amp Eleven is “one of the best sounds we’ve ever had in the studio”. And indeed, the pedal’s natural overdrive is awesome, which applies to the model as well. Simply one of the best amp-in-a-box solutions available.

The number “11” in its name probably refers to Rob Reiner’s [https://www.youtube.com/watch?v=TmgqQRaH5aU This Is Spinal Tap] mockumentary.

[https://tonereport.com/reviews/lovepedal-od11 Tone Report] • [https://www.musicradar.com/reviews/guitars/lovepedal-od11-579546 Music Radar]

The diode-based pedal has these controls: Level, Drive, Bass (cuts bass, model: Bass Cut/Bass Response), Tone (treble). Set Drive to zero and Tone high in the model to boost a clean amp. Get more overdrive with higher Drive settings and adjust Tone and Bass Cut. The Bass Cut on the Basic page of the model is the same as the Bass Response control on the Advanced page. Adjust the control for the guitar pickups and amplifier.

<blockquote>''"On some models the controls are reversed relative to the actual pedal.”'' [https://forum.fractalaudio.com/threads/fractal-audio-drive-models-heartpedal-11-based-on-lovepedal-od11-amp-eleven.148168/post-1752253 Fractal Audio]</blockquote>

[https://www.youtube.com/watch?v=avhQjAmvWMk Sebastian Falvo] • [https://www.youtube.com/watch?v=J0ESr0M_j0M Josh Smith] • [https://www.youtube.com/watch?v=fmoFgQ46qz0 ProGuitarShop: Amp Eleven] • [https://www.youtube.com/watch?v=BfZqv2BhvNw ProGuitarShop: OD11] • [https://www.youtube.com/watch?v=0VqCKYlEENI That Pedal Show: King Of Tone Alternatives] • [https://www.youtube.com/watch?v=5Oukng0DxUY That Pedal Show: Dream Overdrives] • [https://www.youtube.com/watch?v=w4X3GIfFjso Chris Buck] • [https://www.youtube.com/watch?v=MS2LSTUMKxY Rob Chapman] • [https://www.youtube.com/watch?v=w7B6VroMY4k Harry Maes] • [https://www.youtube.com/watch?v=dyIe-bGIdaE Mike Hermans] • [https://www.youtube.com/watch?v=jECGRN1HANU Sam Vilo]

==HOODOO DRIVE (Voodoo Lab Overdrive)==

[[file:x_Hoodoo.jpg|170px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-hoodoo-drive-based-on-voodoo-lab-overdrive.164477/ Original forum thread]

Voodoo Lab has been around since the middle ‘80s, designing and manufacturing several classic effects and audio tools. These days the company is probably best known for their power supplies, powering many pedalboards around the world. This pedal, not be confused with Voodoo Lab’s Sparkle Drive, was released in the ‘90s. It has been discontinued for a long time now. It was based on the DOD OD Preamp 250 (also modeled by Fractal Audio), adding a gain stage. And it does indeed sound like an OD 250. The Overdrive is said to have inspired Fulltone to create the OCD (also modeled by Fractal Audio).

The pedal has 2 knobs: Gain and Volume.

The pedal and the model sound a little on the dark side. Use it with a dirty amp such a Plexi, increase Tone a bit.

[https://www.youtube.com/watch?v=q686nExIPIo Voodoo Lab Overdrive vs Fulltone OCD (gearmanndude)] • [https://www.youtube.com/watch?v=0GcMDhFBu4g&t=55s Why Voodoo Lab Pedals Are Amazing (JHS)]

==HORIZON PRECISION DRIVE (Horizon Devices Precision Drive)==

[[file:x_Precision.png|145px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-horizon-precision-drive-based-on-horizon-devices-precision-drive.164288/ Original forum thread]

Misha Mansoor, also known as Bulb, is a member of the [http://periphery.net/ band Periphery], one of the top djent bands. He’s also a user of Fractal Audio gear. He founded the company [https://horizondevices.com/ Horizon Devices] which released the Precision Drive pedal as their first product. Jim Dunlop/MXR builds the pedal for Horizon Devices.
The Precision Drive ($220) is a modern overdrive, specifically aimed at sculpting metal tones. Basically, it’s very similar to a Tube Screamer, finetuned to work together with already overdriven metal amplifier (or modeler), adding punch, bite, and tightening the low end. According to Horizon Devices, the pedal was developed with modelers and profilers in mind, and [http://ergnerds.com/tag-team-review-horizon-devices-precision-drive/ this review ]even states that the pedal works better with those digital devices than with tube amps. Make sure to check out Horizon Devices’ commercials and tutorials, they are quite funny.

<blockquote>''“Never worry about fighting your tone or your gear again with the Precision Drive, the first modern overdrive made by guitar players for guitar players. The Precision Drive can take any set-up, both tube and digital, and turn it into the perfect modern metal rig with its precise tonal carving controls.”'' [https://horizondevices.com/collections/all/products/precision-drive Horizon Devices]</blockquote>

The pedal has 5 knobs, described in detail in the [https://horizondevices.com/pages/users-guide-pd Users Guide]: Vol, Bright, Drive and Attack which adjusts character and punch (mids) and tightens lows in 6 fixed steps.
Its noise gate has not been modeled.

About the pedal’s Attack control, which in the model is a duplicate of the Bass Response control on the Adv page:

<blockquote>''“Towards the left is more of a lower mids punch, and to the right can get very defined and pick-y. Left is a little more oldschool and thick, right is very modern and clear. You can get tons of unique combinations combining the attack knob with the bright knob. Turning bright up as you turn attack to the left can help keep your sound balanced, and vice versa. Or totally double down with both to the left for doom-y tones, or both to the right for super bright and cutting tones.”'' [https://horizondevices.com/pages/users-guide-pd Guide]</blockquote>

Fractal Audio’s implementation of the Attack control may be even better than the original because it’s not limited to 6 positions.

About the pedal’s Volume control:
<blockquote>''“6 on the Precision drive is roughly equal to 10 on a Tubescreamer. So starting the volume at noon is usually a good bet. Adjust to taste from there.”'' [https://horizondevices.com/pages/users-guide-pd Guide]</blockquote>

About the pedal’s Bright control:
<blockquote>''“We made sure this control could be very bright in order to help make dark or muddy amps cut. So be careful when using the pedal for mid/low gain tones, because it can be a bit harsh in the upper portion of its range. When doing this, don’t be afraid to turn this knob pretty far to the left. It will tame it right up!”'' [https://horizondevices.com/pages/users-guide-pd Guide]</blockquote>

About the pedal’s Drive control:
<blockquote>''“You’re going to want to start with this near zero at first, as with most pedals. A cool trick is to dial in a really dry and clear tone, then slowly turn the drive knob up to around 1-2 until you get the level of saturation and thickness you’d like. We put a lot of effort into this portion of the circuit to make it actually usable, so feel free to turn it up for mid-gain tones, or to add saturation and sustain to your solos.”'' [https://horizondevices.com/pages/users-guide-pd Guide]</blockquote>

The models are featured in some factory presets, [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets search this wiki page] for “Horizon”.

[https://www.youtube.com/watch?v=ucI7e0j_Mfg Ola Englund] • [https://www.youtube.com/watch?v=xZGY49yOHTo Rabea Massaad] • [https://www.youtube.com/watch?v=4otM453lZX8 Guitar World] • [https://www.youtube.com/watch?v=TwvsDMuwg1M Horizon Devices] • [https://www.youtube.com/watch?v=T3dn9HU_oqs Tone on a Budget] • [https://www.youtube.com/watch?v=0pA_dmcZtBs Tutorial 1] • [https://www.youtube.com/watch?v=E9r-7GIpGYs Tutorial 2] • [https://www.youtube.com/watch?v=pIWIYYgAru0 Tutorial 3] • [https://www.youtube.com/watch?v=WDT7-0vWpuM Sweetwater] • [https://www.youtube.com/watch?v=PQk7eQNOcgo Jason Richardson] • [https://www.youtube.com/watch?v=HbJUskPMQKk Riffs, Bears and Gear] • [https://www.youtube.com/watch?v=FFIgwizy6t0 Pete Thorn]

==INTEGRAL PRE (TC Electronics Integrated Preamp)==

[[file:TC.jpg|150px|left]]

This device from the '90s helped Fredrik Thordendal from Meshuggah shapes his heavy metal sound. It's a simple boost, without an on/off switch. Running on high voltage, it boosts the signal with a load of dB. The active Bass and Treble controls make it possible to cut frequencies to make the sound very tight.

Some manufacturers created clones. [https://peperspedals.bigcartel.com/product/dirty-tree Pepers' Pedals Dirty Tree] is a popular one. Fortin made Thordendal a signature version of this boost. Fortin's Grind pedal equals the original at fixed settings.

"''The Fortin Grind is a TC Electronics Pre with the tone controls in a fixed position.''" [https://forum.fractalaudio.com/threads/fortin-grind-pedal.206603/#post-2627219 Fractal Audio]

[https://www.youtube.com/watch?v=oZ2YLAxHBYo Leon Todd: Fractal model] • [https://www.youtube.com/watch?v=LKSZboGo5PQ shnobel: original device] • [https://www.youtube.com/watch?v=n3pB-DD9dPQ Leon Todd: original device] • [https://www.youtube.com/watch?v=q5877J7rcLs Amps, Pedals & Pickups: Dirty Tree] • [https://www.youtube.com/watch?v=JV-RTP4yd4w Riffs, Beards & Gear: Dirty Tree] • [https://www.youtube.com/watch?v=8KsiHmyCsvc Fortin Grind vs Fortin 33]

==JAM RAY (Venuram Jan Ray)==

[[file:x_Jam.jpg|150px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-jam-ray-based-on-vemuram-jan-ray.148184/ Original forum thread]

[http://www.vemuram.com/ Vemuram’s Jan Ray] (Japan) is a coveted boost and overdrive, endorsed by an impressive [http://www.vemuram.com/artists.html list of artists], including Michael Landau, Oz Noy, Scott Henderson, Pete Thorn, Matt Schofield and others. This boutique pedal costs close to $400. It’s been the topic of heated discussions on internet forums. [https://www.youtube.com/watch?v=5Oukng0DxUY This That Pedal Show episode] demonstrates the similarities between the Timmy, Jan Ray and Amp Eleven (all have been modeled by Fractal Audio). It shines when combined with models of Fender amps. A signature version was made for Mateus Asato (limited edition).

It can operate as a clean boost. It can turn a clean amp into a mildly overdriven one, and as such operates as an amp-in-a-box pedal. The pedal provides natural distortion, as well as crispness on the top, along with warmth and softness in the lows (quoted from [http://www.mixdownmag.com.au/vemuram-jan-ray MixDown’s review]). It offers harmonic content, sustain and transparency, so you’ll still hear the characteristics of the guitar you’re playing.

<blockquote>''“The Jan Ray was designed to recreate the punchy clear tone of the Blackface Fender amps from the 60’s. So-called the “Fender Magic 6” sound. An easy to handle overdrive keeping the characteristics of the guitar, with great sustain without any unnatural compression.”'' [http://www.vemuram.com/ Vemuram]</blockquote>

“Magic 6” refers to setting Volume to 6, Treble to 6, Middle to 3 and Bass to 2 (3 x 2 = 6) on a Fender amp such as the Super Reverb, as explained in the Guide to the Fractal Audio Amp Models.

<blockquote>''"The Jan Ray is a slightly modified Timmy which itself is a modified Tube Screamer (albeit heavily modified).”'' [https://forum.fractalaudio.com/threads/fractal-audio-drive-models-jam-ray-based-on-vemuram-jan-ray.148184/post-1752512 Fractal Audio]</blockquote>

The diode-based pedal has these controls (not labeled on the pedal): Volume, Bass (high-pass), Treble, Gain. Start with low Drive and the other controls at default.

[https://www.youtube.com/watch?v=0XtsHI-5H8s Absolute Music] • [https://www.youtube.com/watch?v=nF7RlO95bME Haar Guitars] • [https://www.youtube.com/watch?v=scfT34dBs08 intheblues] • [https://www.youtube.com/watch?v=jOOOGmCIp24 Sam Vilo] • [https://www.youtube.com/watch?v=Xs2aV-cGHcI Livingroom Gear Demos] • [https://www.youtube.com/watch?v=5Oukng0DxUY That Pedal Show: Dream Overdrives] • [https://www.youtube.com/watch?v=dc0ok1VsotM Guitar Bonedo] • [https://www.youtube.com/watch?v=CdY9h1fnQE0 gearmanndude] • [https://www.youtube.com/watch?v=Fdw8V9Vgbho Jan Ray vs MXR Timmy] • [https://www.youtube.com/watch?v=C6rrsNVvtXE Paul Davids]

==KLONE CHIRON (Klon Centaur / KTR)==
[[file:Klon.jpg|250px]] [[file:KTR.png|225px]]

The illustrious Klon Centaur overdrive was made by Bill Finnegan between 1994 – 2008. People buy used Centaurs for ridiculous amounts of money. It’s assumed that around 8.000 original Centaurs exist. Josh Scott of JHS Pedals has one with serial no. 2, which he put up [https://www.guitarworld.com/news/jhs-pedals-owner-josh-scott-is-selling-the-first-ever-klon-centaur-for-dollar500000 for sale for $500,000]. For those who can afford it (and secure it), a Klon is a mainstay pedal on the pedalboard. John Mayer is just one of its famous users.

There are Gold and Silver versions of the Centaur. While the builder has repeatedly [https://www.premierguitar.com/gear/bill-finnegan-klon stated that they sound the same], many players think otherwise.

The “gooped” Centaur circuit board (covered in black epoxy) didn’t stop people from investigating. As soon as the schematics became available in 2009, many builders started manufacturing clones, some of which come close.

After a break, Bill Finnegan introduced the Klon KTR in 2012. Easier to manufacture, with the same sound as the Centaur. The announcement of the KTR is [http://www.klon-siberia.com still online]. The printed text on the KTR reminds the player of the Centaur’s history and reads: “Kindly remember: the ridiculous hype that offends so many is not of my making”. Some of the letters are colored slightly different to make out: “KLON”.

Like the Centaur, the KTR delivers the rich harmonics of a loud overdriven amp, without adding color of its own (unlike the Tube Screamer, for example). It’s designed to push an amp that’s already on the edge. It’s also an excellent clean boost at low gain settings.

<blockquote>''"The Centaur is a true overdrive , and whatever it’s providing in the way of distortion should have some amp distortion to blend in with. For the really natural cranked-amp sounds the unit is capable of, your amp needs to be turned up some, enough to give you at least a measure of the good stuff on its own.”'' [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-version-20-03-release.185459/page-11#post-2290429 Klon Siberia]</blockquote>

The Klon circuit has JFET-based opamps and specific Germanium diodes. It’s unique because it runs multiple audio paths, with the Gain knob controlling the mix between the distorted and clean paths. The diodes don’t come into action until the Gain knob is turned up. That’s why players who use it for overdrive, set Gain at 10:30 or higher.

In 2021 Bill Finnegan [https://www.guitarworld.com/news/bill-finnegan-klon-ktr-production-update announced that he needed to change the circuit], because he was running out of the specific Germanium diodes he uses. He assured that the sound would be retained, [https://www.youtube.com/watch?v=Lp6fxy4efRI as demonstrated here].

[https://en.wikipedia.org/wiki/Klon_Centaur Wikipedia] • [https://www.electrosmash.com/klon-centaur-analysis Electrosmash] • [https://www.premierguitar.com/gear/reviews/best-klon-clone Klon vs. Klone] • [https://www.premierguitar.com/gear/bill-finnegan-klon Builder's Profile] • [https://reverb.com/news/the-cult-of-klon the Cult of Klon (Reverb]

The pedal has these controls: Gain, Treble, Output. With Output at noon, it’s already louder than unity gain. That’s a good thing, because [https://www.premierguitar.com/gear/bill-finnegan-klon Bill Finnegan advises to set Output higher than the bypassed signal]. With Gain at its lowest, and Output turned up above unity gain, the Klon operates as a clean boost. Many players prefer to use it that way. Set Gain at 10:30 or higher for its famous overdrive sound.

Treble is neutral at noon.

<blockquote>''“Don’t be afraid to use the Treble control. Unlike the tone controls on most pedals, this one is natural-sounding and usable throughout its entire range. The middle part of the range was deliberately broadened to allow extremely fine gradations in treble response, so such off- center settings as ten o’clock and two o’clock, for example, are not extreme and shouldn’t be shied away from. Trust your ear, and use the control.”'' [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-version-20-03-release.185459/page-11#post-2290429 Klon Siberia]</blockquote>

Fractal Audio has not disclosed whether the “Klone Chiron” model is based on the Centaur or the KTR.

<blockquote>''"While working on the Klon algorithm, I discovered a few things.”'' [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-version-20-03-release.185459/post-2289914 Fractal Audio]</blockquote>

While the Klon and its virtual equivalent are “special”, you shouldn’t overlook other available models of transparent overdrives. For example, the Heartpedal 11 and the Timothy models also provide warm-sounding natural overdrive. Before the Klone Chiron model was introduced by Fractal Audio, people used the FET Boost model to get close to the sound of a Klon.

[https://www.youtube.com/watch?v=otkW_q0_VIU&t=967s Diode-Based Overdrive and Distortion Effects] • [https://www.youtube.com/watch?v=WcWqMuPSfgs Klon Comparison Demo with Bill Finnegan] • [https://www.youtube.com/watch?v=T00XAMazpoA Klon KTR Prototype & Development Board with Bill Finnegan] • [https://www.youtube.com/watch?v=EBaYe4mk6z4 five watt world] • [https://www.youtube.com/watch?v=eytykYcfkeI Jack Fossett] • [https://www.youtube.com/watch?v=RWPvOuISvR4 Andrew Cheng] • [https://www.youtube.com/watch?v=l5Sou9v7q9U Gladesville Guitar Factory] • [https://www.youtube.com/watch?v=y8L2czCPg6M Friday Fretworks] • [https://www.youtube.com/watch?v=289ZkXIWXfU Musictoyznetwork] • [https://www.youtube.com/watch?v=WQWl7AMmUmI Curtis Kent] • [https://www.youtube.com/watch?v=uFpF0CijO8k Karl Verkade] • [https://www.youtube.com/watch?v=gGFj4jk2lfg Camilo Velandia] • [https://www.youtube.com/watch?v=vcODeqaCBNg Living Room Gear Demos] • [https://www.youtube.com/watch?v=XnDEadZTV80 That Pedal Show] • [https://www.youtube.com/watch?v=olPoya08kBA Klon Centaur vs Vintage Ibanez Tube Screamer] • [https://www.youtube.com/watch?v=c7dNklFi6ws shnobel] • [https://www.youtube.com/watch?v=8tjQXTMfxYY The Ultimate Klon Pedal Blindfold Challenge (Andertons)] • [https://www.youtube.com/watch?v=FiUCpB4R38g King of Tone vs Klon Centaur] • [https://www.youtube.com/watch?v=aK5H0e9Ejmc $7K VS $30 Clone (JHS)] • [https://www.youtube.com/watch?v=6Ast9xQyTEU Everything Klon Centaur (JHS)] • [https://www.youtube.com/watch?v=ap4xZXezlbc Emerald City Guitars] • [https://www.youtube.com/watch?v=pFOD6s0IRoM Bad Monkey vs KLON (JHS)] • [https://www.youtube.com/watch?v=LJGos1D1ha8 JHS Pedal NOTAKLÖN DIY kit]

==M-ZONE DISTORTION (BOSS MT-2 Metal Zone)==

[[file:x_MT.jpg|140px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-m-zone-dist-based-on-boss-mt-2-metal-zone.123396/ Original forum thread]

Does [https://www.boss.info/us/products/mt-2/ BOSS] really need an introduction? This subsidiary of Roland has released an enormous variety of pedals over the years and continues to do so today. Loathed by some because of their non-boutique character, highly praised by others because of build quality and tone. BOSS may be mainstream, but they have created lots of classics, used by Prince, Gary Moore and many more.
The Metal Zone pedal from 1991 in particular is responsible for divided opinions and heated discussions. It was the era of Metallica’s Black Album. This pedal, the successor of the Boss HM-2, enabled players to turn their clean amps into heavy metal monsters with insane amounts of distortion and compression/sustain. So, it was popular with bedroom guitarists. So much that it hardly matters what type of guitar is being played: the pedal makes them sound the same. It’s one of BOSS’ best-selling pedals ever and at the same time probably the most hated. And it is still being sold by BOSS today ($150). In fact, in 2018 BOSS released the [https://www.boss.info/us/products/mt-2w/ MT-2W] ($150), a Waza Craft version. Many companies, including Analog Man and Keeley, offer modding services.
The diode-based MT-2 has peaks at 100 Hz and 5 kHz and is widely scooped around 500 Hz.
The pedal can be used as a preamp by itself, going into the effects return of a guitar amplifier to bypass the amp’s own preamp.

<blockquote>''“The MT-2 is the metal pedal that followed the HM-2. It was released a couple of years before the HM-3 and was an instant success. It is one of the best-selling Boss pedals of all time. The Metal Zone produces a distortion that is a bit smoother than the HM-2 and HM-3. In addition to the LEVEL and DIST controls it’s got a 3 band sweepable parametric equalizer that gives complete control over the MT-2’s tonal spectre.”'' [http://www.bossarea.com/boss-mt-2-metal-zone Bossarea]</blockquote>

[http://blog.zzounds.com/2016/01/06/25-years-in-the-metal-zone/ 25 years in the Metal Zone] • [https://www.tonestart.com/?s=metal+zone Tone Start] • [http://www.gitarrebass.de/workshops/boss-metal-zone-mt-2/ Gitarre & Bass #1] • [https://www.gitarrebass.de/workshops/effektiv-metal-pedale/ Gitarre & Bass #2] • [https://rolandcorp.com.au/blog/metal-zone-youre-using-it-wrong You’re Using It Wrong]

The pedal has these controls: Level, 3-band EQ (Low, Mid, High), active), Distortion: amount of distortion. The Mid control is where it counts. Select the desired frequency and turn Mid up and down. Also, fight the urge to turn up Distortion too much.

While the MT-2 is infamous for the sounds that bedroom metal guitar players get from it (scooped, far too much gain), it can deliver acceptable tones, as demonstrated in some of the videos below.

[https://www.youtube.com/watch?v=GP0mKB3d3Qg BOSSchannel] • [https://www.youtube.com/watch?v=BUABS0LWByM Worst Distortion Pedal Ever?] • [https://www.youtube.com/watch?v=l6x6AjsKaMk That Pedal Show] • [https://www.youtube.com/watch?v=_5PX4Fl6Mu4 Rabea Massaad] • [https://www.youtube.com/watch?v=b-2mBcmfQ7w&t=850s Simon Neil from Biffy Clyro] • [https://www.youtube.com/watch?v=ihMARdquhqc Reverb.com] • [https://www.youtube.com/watch?v=YX83ulNWyKA GMR] • [https://www.youtube.com/watch?v=uxGEO-PQnsc&t=28s HearGear] • [https://www.youtube.com/watch?v=uut1ol_HfCU World Music Supply] • [https://www.youtube.com/watch?v=hWLAPSB9MAM blondegraemey] • [https://www.youtube.com/watch?v=F4-dNnh6MbA Mark Holcomb] • [https://www.youtube.com/watch?v=nxRe99Tjlwg Ola Englund] • [https://www.youtube.com/watch?v=YBZqZiIKwqA Will it blues?] • [https://www.youtube.com/watch?v=8mCXSDb7MKk Bass demo] • [https://www.youtube.com/watch?v=Zg6JYTbt0d4&t=833s Boss Is Best (JHS)] • [https://www.youtube.com/watch?v=XTGmfsKHcXo&t=989s History Of Guitar Distortion (JHS)] • [https://www.youtube.com/watch?v=IsrHC3AGAEs Shred Master vs Metal Zone] • [https://www.youtube.com/watch?v=dl7Y4YlkeYI Is it really a pre-amp? (Wampler)]

==MASTER FUZZ (Gibson Maestro Fuzz-Tone FZ-1A)==

[[file:x_Maestro.jpg|200px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-master-fuzz-based-on-gibson’s-maestro-fuzz-tone-fz-1a.123363/ Original forum thread]

The ’62 Maestro Fuzz-Tone by Gibson was the first fuzz pedal, relying on germanium transistors. The idea for the pedal was born when musicians looked for a way to reproduce the sound of a broken console transformer. It became famous after Keith Richards used one in ’65 on “Satisfaction” [https://www.ultimate-guitar.com/news/general_music_news/keith_richards_admits_iconic_rolling_stones_riff_wasnt_supposed_to_be_played_on_guitar_explains_who_jack_from_jumpin_jack_flash_is.html?fbclid=IwAR3jKkPl6d75FhcO-xHHjUfKDPdSwfihTTm3bQCQjnfsXKlCvvf9N2ASdAE instead of a horn section]. The Fuzz-Tone led to the development of the Tone Bender and other fuzzes. Pete Townsend’s Fuzz-Tone sold for an astonishing $12.000 (for a few resistors and capacitators). Other users include Eddie Hazel. Back then, the purpose of a fuzz box also included emulating instruments like violin, trumpet, cello, and organ. Some compare the sound of the riff in “(Can’t Get No) Satisfaction” to that of a trombone. [https://www.youtube.com/watch?v=VAWwBEx3Qkc Listen to this original demonstration record.]
Maestro is owned by Gibson. Here’s a [https://www.maestroelectronics.com/en-US/page/maestro-timeline company timeline]. In 2022, Maestro was relaunched, presenting the [https://www.maestroelectronics.com/en-US/Pedal/Fuzz-Tone Fuzz-Tone FZ-M] as part of the “Original Collection” line of effects.

<blockquote>''“The Maestro FZ-1 Fuzz-Tone was the first fuzz distortion device to become widely available on the market for electric guitars and basses, although there had been other prototype devices made. It was designed and manufactured by Gibson. The Maestro FZ-1 (along with its almost identical update the FZ-1a) achieved a peak of popularity in the 1960s. The device was used by Keith Richards in the Rolling Stones' 1965 hit "Satisfaction" and became a favorite of many garage rock and psychedelic acts of the time. Gibson re-issued the FZ-1a in the 1990s, but later discontinued the model. The Maestro FZ-1 sported a three-germanium transistor circuit with RCA 2N270 devices, powered by two 1.5-volt batteries, and a lead cable to connect it to an instrument (bass as it was originally intended, or guitar). Germanium devices are temperature sensitive, and the effect responds to the incoming signal's amplitude (volume) consistently. Upon release, Gibson/Maestro made a demonstration disc available, featuring sound samples of the different settings of the pedal and guitar combination, emphasizing the "brass-like" quality of certain tones. The circuit made its way into the body of Gibson's EB-0F "fuzz basses" (circa 1964). Before the Rolling Stones' hit, Fuzz Tone's sales were abysmal. In late 1965, when the original units sold out, the circuit was revised, using 2N2614 or 2N2613 transistors, with pertinent biasing network, powered by a single, 1.5-volt battery. The model was re-designated as the FZ-1a, keeping the same wedge shaped enclosure as the FZ-1. In 1968, an updated model with a different look and sound was introduced, with a circuit designed by Robert Moog using a 9-volt power supply and alternatively 2 or 4 silicon transistors, and labelled the Maestro FZ-1B. It went through 3 circuit revisions. In the 1970s Maestro came out with the FZ-1S Super-Fuzz, which had a distinctly different look and sound than previous models.”'' [https://en.wikipedia.org/wiki/Maestro_FZ-1_Fuzz-Tone Wikipedia]</blockquote>

[https://www.ultimate-guitar.com/articles/features/brief_history_of_fuzz_effect_and_5_most_important_vintage_fuzz_pedals-94813 Brief History of Fuzz (Ultimate Guitar)] • [https://reverb.com/news/when-did-guitarists-first-use-fuzz-wah-and-other-transistor-based-effects When Did Guitarists First Use Fuzz, Wah, And Other Transistor-based Effects? (Reverb)]

The Maestro is a simple pedal with just two knobs at the side: Volume and Attack (amount of fuzz, model: Drive).

[https://www.youtube.com/watch?v=nrIPxlFzDi0 (I Can't Get No) Satisfaction by The Rolling Stones] • [https://www.youtube.com/watch?time_continue=11&v=U9UI92m77bY The 2000 Pound Bee by The Ventures] • [https://www.youtube.com/watch?v=VAWwBEx3Qkc Maestro Fuzz-Tone FZ-1 1962 Demonstration Record] • [https://www.youtube.com/watch?v=8trGBcA0Ku0 Drowninginguitars] • [https://www.youtube.com/watch?v=ajj92dIifGY Gibson Audio Sample] • [https://www.youtube.com/watch?v=EwS4-Vn4z_8 Gibson Maestro Fuzz Tone Demo FZ-1 A] • [https://www.youtube.com/watch?v=CF9ha6dBon4 Fuzz Tone demo] • [https://www.youtube.com/watch?v=ABAz5pyP16Y Fuzz Tone 2 demo] • [https://www.youtube.com/watch?t=399&v=XTGmfsKHcXo History Of Guitar Distortion (JHS)] • [https://www.youtube.com/watch?v=iBjXiNVTWZI&t=260s The First Guitar Effects Ever (JHS)] • [https://www.youtube.com/watch?v=iK4hBbVOnHQ The First Pedal Demo Ever (JHS)] • [https://www.youtube.com/watch?v=Xc8IUh9V330 Gibson TV] • [https://www.youtube.com/watch?v=lsYe1Te7VEs Pedal of the Day]

==MAXOFF 808 (Maxon OD-808)==

[[file:x_OD808.jpg|235px|left]]

[https://maxonfx.com/products/reissue-series-guitar-effects-pedals-maxon-overdrive-od808 Maxon] in Japan built the original Tube Screamers for Ibanez. They’ve also released these under their own brand name. The [https://maxonfx.com/collections/reissue/products/reissue-series-guitar-effects-pedals-maxon-overdrive-od808 OD808] ($200) is a twin brother to the Ibanez Tube Screamer TS808, dating back to 1979. It sounds almost identical using the same op-amp type and almost the same electronics, with all the bluesy characteristics for better and for worse. The Maxon sounds slightly smoother and creamier, with less mids. This, plus compression and bass roll-off, makes it a popular boost pedal among hard rockers. For more information, read the sections about the Tube Screamers.

''“Can a pedal be considered a clone if it’s made by the company that made the original?!? Maxon designed the original OD808 overdrive circuit in the late 1970’s – they then rebranded this pedal for Ibanez as the TS808 Tubescreamer, and the rest is history... The OD808 Reissue offers up all the warm, creamy, organic overdrive as the original and then some. Never one to rest on their laurels, Maxon has tweaked the current version ever so slightly to reduce noise level while retaining the legendary “808” tone (see Tech Talk below). The OD808 is the perfect pedal for adding smooth, tube-like overdrive to any clean amp – use it as a secondary dirt channel to beef up a song’s chorus section, or keep it on all the time for the crunchy tone that has defined rock and roll. The OD808 is also ideal for pushing an already overdriven amp over the edge, a ‘la Stevie Ray Vaughan. Hell, stack two of them together like Stevie did and the house is a rockin’! You’ve never heard – or felt – bluesy goodness like this before… In recent years the OD808 has been adopted as the overdrive of choice by a generation of guitarists in a most unlikely musical genre – metal. Turns out that the OD808’s mild compression and slight low-end cut are perfect for tightening up high-gain amps; allowing fast note runs to stand out with clarity while making rhythms tight and punchy. Just listen to any recording by Grammy-award winning Producer/Killswitch Engage founder Adam Dutkiewicz to hear how the OD808 has become the voice of a whole new generation of metal guitarists. Besides the fact that the Maxon OD808 Reissue sounds richer, warmer, and BETTER than the Ibanez TS808 Reissue, there are also these facts to consider. Maxon developed the OD808 circuit more than 40 years ago, and since then it’s become the most used, most imitated and most lauded overdrive circuit of all time. While the 808-style overdrive circuit is commonplace nowadays, in 1979 it was a unique design and an industry first. The secret behind the legendary “808 tone” lies in the amplifier section of the circuit. Rather than having separate amplifier and clipping stages, the OD808 features a signal-distorting diode (Panasonic #MA150) located in the negative feedback loop of the amplifier stage. The OD808 distorts signal in the amplifier circuit itself which yields a smoother, milder, more natural sounding distortion than a separate clipping stage. This is also the reason that the IC type used in the circuit has such a large impact on the unit’s tone. The Reissue uses the correct JRC4558 Op Amp that made the 808 the tone of legend. It should be noted that the Reissue Series OD808 uses different output resistors than the original version. Vintage TS808’s are susceptible to microphonic noise due to static electricity buildup on the chassis. To improve performance, the positions of the output resistors on the reissue OD808 were reversed and their values increased in order to reduce noise levels. This circuit change has no audible affect on the sound of the unit, save for reducing the noise levels.” [https://maxonfx.com/products/reissue-series-guitar-effects-pedals-maxon-overdrive-od808 Maxonfx]

[https://cdn.shopify.com/s/files/1/0069/5363/1844/files/Maxon-Reissue-Series-Manual.pdf?18239666655055042628 User’s Guide with sample settings] • [https://guitar.com/review/effects-pedal/maxon-od808-od-9/ OD808 & OD-9 vs TS-9] • [https://legendarytones.com/maxon-od808-overdrive/ Legendary Tones] • [https://maxonfx.com/pages/news-and-reviews-of-maxon-guitar-effects-pedals Reviews on Maxonfx.com] • [https://www.sweetwater.com/insync/27-tube-screamer-style-pedals-compared-which-is-right-for-you/27 Tube Screamer-style Pedals Compared]

<blockquote>''(compared to the Tube Screamer) "Maxon sounds a bit different due to the different op-amp and diodes. Smoother and less midrange honk."'' [https://forum.fractalaudio.com/threads/maxon-od808.176967/post-2152725 Fractal Audio]</blockquote>

[https://www.youtube.com/watch?v=2iqymUQgnZwProGuitarShopDemoes: ProGuitarShop] • [https://www.youtube.com/watch?v=S6IFZ-ygvKw PMTVUK] • [https://www.youtube.com/watch?v=bG19HEY-06o Intheblues] • [https://www.youtube.com/watch?v=VR6MxDg0iiA EytschPi42] • [https://www.youtube.com/watch?v=w5B1S3woynQ gearmanndude: Maxon 40th Anniversary OD808 versus Stock] • [https://www.youtube.com/watch?v=TZjLO_ECt1U gearmanndude] • [https://www.youtube.com/watch?v=y7ozkgpIryw&t=155s Do all tubescreamers sound the same? (Wampler)]

==MCMLXXXI DRV (1981 Inventions DRV)==
[[file:x_1981.png|275px|left]]

The great-looking DRV distortion is one of the latest pedals on the boutique overdrive market, with a corresponding price ($250). It started off as a clone of the famous Pro Co RAT, but brings some good stuff of its own, making it more versatile than a RAT. The DRV works great with a VOX-type amp. It puts juicy sounds, and sounds far better with a clean amp than the RAT does.

[https://guitar.com/review/effects-pedal/review-1981-inventions-drv/ Review by Guitar.com]

<blockquote>''“A highly nuanced preamp/distortion pedal designed in collaboration with Jon Ashley of Bondi Effects. Through four years of abandoned prototypes and circuit tweaking, I think that we have emerged with something really special here. I wanted the DRV to be an extension of myself and what I personally needed from a distortion pedal. It is vintage minded in sound and concept. I find that there is a wide variety of sounds that can be found from tweaking three highly interactive knobs, which is how I like to tweak when I am finding a sound. Clear and harmonic-rich warmth with guitar specific midrange, which brings a lot of clarity to almost any instrument. I think I’m most proud of the lower gain sections of the pedal, where preamp meets distortion. The DRV has a unique dynamic range and sensitivity, where instead of going clean to slightly overdriven, it goes from clean to slightly distorted. I also love the thick and yet clear fuzz sounds that you’ll find in the high gain settings.”'' [https://1981inventions.com 1981 Inventions]</blockquote>

The DRV has three controls: Drv, Cut (treble roll-off) and Vol. The controls interact with each other. When adjusting Drive, adjust Cut too. Don’t hesitate to turn Cut close to fully clockwise (cutting treble).

Try Drive between 2.50 and 5, Cut at 7.5 and Level at 8.

<blockquote>''"Doesn't look like it has much different gain. Pre-distortion shaping is different.”'' [https://forum.fractalaudio.com/threads/is-there-a-way-of-changing-the-range-of-gain-in-the-drive-block.168323/post-2021891 Fractal Audio]</blockquote>

[https://www.youtube.com/watch?v=4uORmOmzmqk Living Room Gear Demos] • [https://www.youtube.com/watch?v=SQPHrpiv1X8 Pedal of the Day] • [https://www.youtube.com/watch?v=gacCFDRauy4 1981 Inventions DRV: The King of Dirt Pedals] • [https://www.youtube.com/watch?v=kqXRA9Ag10c 1981 Inventions DRV vs 1985 ProCo RAT (shnobel)] • [https://www.youtube.com/watch?v=FqoYvYB7Wfg Distortion LTD] • [https://www.youtube.com/watch?v=GlB0JmaqGIM&t=602s 5 High-Gain Pedals You Probably Haven’t Heard Before (Reverb)] • [https://www.youtube.com/watch?v=Pyk7bNBNV-g Eric Merrow] • [https://www.youtube.com/watch?v=C6pKuUEdTYY Buddy Blues] • [https://www.youtube.com/watch?v=V_Uz6bWLzag IkeGuitar] • [https://www.youtube.com/watch?v=s6u4hsugzOg Mark Johnston]

==MICRO BOOST (MXR Micro Amp)==

[[file:x_Micro.png|150px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-micro-boost-based-on-mxr-micro-amp.123367/ Original forum thread]

MXR, now owned by [http://www.jimdunlop.com/products/electronics/mxr Jim Dunlop], was one of the largest effects manufacturers in the ‘70s and ‘80s. Several of their products are now considered to be classics: Dynacomp, Phase 90 and 100, Flanger.
The Micro Boost model is based on MXR’s Micro Amp ($80), an op-amp driven clean boost pedal. It is a redesign of the MXR Distortion + pedal (also modeled by Fractal Audio) without the distortion, reportedly. It was one of the first of its kind. It doesn’t provide distortion of its own (no clipping). It just increases the signal level, causing the amp to generate more gain, and therefore acting as a gain stage. While many boost pedals claiming to be transparent, still add color to the sound, the Micro Amp really is very neutral. Pete Cornish’s SS2 reportedly is very similar to the Micro Amp.

[http://www.electrosmash.com/mxr-microamp ElectroSmash] • [https://www.tonehome.de/mxr-innovations/micro-amp/ Manual and schematic]

<blockquote>''“Adding a preset amount of gain with just a single control, the Micro Amp is a great way to boost your signal for lead work or adjust between two different guitars with unmatched output (i.e. humbuckers to single-coils). It can also provide a permanent boost in a long effects chain where signal drop off is a problem.”'' [https://www.jimdunlop.com/product/m133-7-10137-00660-7.do?sortby=ourPicksAscend&page=2&refType=&from=fn MXR]</blockquote>

Keith Barr (president and co-founder of MXR), when asked about the Micro Amp (source: [http://amgtve.formusiciansonly.com/ Analog Man's Guide to Vintage Effects]): ''"That was one of the later boxes that we didn't really care about”''.

There’s only a single Gain control (model: Drive) that adds up to 26dB.

You can argue about the need for a Drive block that acts as a clean boost in a digital environment, because there are less CPU-hungry solutions. As a matter of fact, there isn’t much difference between the Micro Boost at default settings and a “null” Filter block with matched output level and High Cut. But if you are going to create a digital replica of your rig from the ‘80s, include the Micro Boost.

[https://www.youtube.com/watch?v=AtG2BimR4BE ProGuitarShop] • [https://www.youtube.com/watch?v=Zf-5R4slm2M Vintage MXR Micro Amp vs Newer MXR Micro Amp (shnobel)] • [https://www.youtube.com/watch?v=EtT2gGU-6fU&t=82s 1970’s Op-Amp Distortion (JHS Pedals)] • [https://www.youtube.com/watch?v=iaP-ng3W7zw When John Frusciante Uses The Micro Amp]

==MID BOOST (custom model)==

[[file:logo.jpg|150px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-mid-boost.123374/ Original forum thread]

The guitar is an instrument that lives in the middle frequencies area. It has no business competing with bass (low frequencies), cymbals (high frequencies), etc. The mids are where guitars shine. Emphasizing those frequencies makes a guitar cut through the mix, which works far better than increasing volume. That’s why some amps, pedals and guitars are equipped with mid-boosting options.

[http://www.premierguitar.com/articles/21122-the-recording-guitarist-the-abcs-of-eq Premier Guitar's The ABCs of EQ] • [http://wiki.fractalaudio.com/axefx2/index.php?title=EQ EQ in the Fractal Audio wiki]

This Mid Boost is a custom model by Fractal Audio. These models have no specific real-life equivalents. They solely exist within Fractal Audio’s processors, implementing ideas and improvements on existing pedals. The Mid Boost model, based on a virtual silicon transistor, does just that: it boosts the mids through an already overdriven amp. It makes leads and solos stand out. It sounds like a cocked (fixed position) Wah pedal. A similar effect can be achieved through a GEQ block, but this model also adds distortion if desired. A little tweaking gets you a lead tone like Brian May’s. Note that the model sucks a considerable amount of bass from the signal. The frequency on which the model operates, is not adjustable. The Drive parameter determines the amount of overdrive. The model is also available as an input boost type in the Amp block.

[https://www.youtube.com/watch?v=vraAIt_ismU Fender Eric Clapton Stratocaster Mid Boost] • [https://www.youtube.com/watch?v=aU92B4j0fSI One Control Purple Humper mid boost] • [https://www.youtube.com/watch?v=3cT_SldJiGQ VFE Pedals Focus Mid Boost] • [https://www.youtube.com/watch?v=Q2ZJn-uokSg Demeter Fat Control Midboost]

==MOSFET DISTORTION (Ibanez MT10 Mostortion)==

The other 'green' overdrive, part of the '90s Ibanez 10 Series which also included John Mayer's favorite Tube Screamer version. It's different from the Tube Screamer though.

Visually not the prettiest pedal, but it's a coveted item in the Nashville scene (like the Nobels ODR), so originals come at a hefty price.

While MOSFET-based, the gain comes from clipping does. The 3-band tone stack comes after the gain.

The [https://karmaguitaramps.com/mtn-10/ Karma MTN-10] and Wampler's Mofetta are clones.

[https://www.youtube.com/watch?v=0L2MJwlZM8M Everything Guitar] • [https://www.youtube.com/watch?v=OOS5wPkouMs Ronquillo] • [https://www.youtube.com/watch?v=Kr2kwkTwQTE Your Guitar] • [https://www.youtube.com/watch?v=FJVI7jRUce8 Pete Thorn] • [https://www.youtube.com/watch?v=ORqSnJpOWA4 Wampler Mosfetta]]

==NOBELLIUM OVD-1 (Nobels ODR-1 BC Natural Overdrive)==

[[file:Nobels.jpg|150px|left]]

A cheap but beloved workhorse overdrive, especially in the Nashville session player scene. [https://nobels.de Made in Germany]. Famous users include Carl Verheyen, John Shanks and Tim Pierce. It's green but it isn't a Tube Screamer. Nobels also produces mini and anniversary editions of the pedal.

The name says it all: natural overdrive. It adds gain while leaving the guitar's own sound largely untouched. Many players think that's a good thing. However, some think of transparency as blandness. The pedal reacts very well to the guitar's volume setting. It's often used to fatten ups single coils. The designer started his own company Nordland and produces the [https://nordland-electronics.de Nordland ODR-C], a further refined version. [https://www.vemuram.com Vemuram's ODS-1], [https://www.wamplerpedals.com/products/distortion-overdrive/belle/ Wampler's Belle] ands the Way Huge STO are based on the ODR-1.

The ODR has clipping diodes in the opamp. Controls are Drive, Spectrum (adjusts bass as well as treble, but not mids), Level, Bass Cut.

The Bass Cut ("BC") switch on the current edition is meant to be used with humbuckers. It's modeled via the Bass Response control. Set the Bass Response to 1.0 to duplicate the response of the pedal with the Bass Cut switch engaged. Set Bass Response to 5.0 to duplicate response with BC switch disengaged.

[https://nordland-electronics.de/en/blog/odr-1.html More ODR-1 history]

[https://www.youtube.com/watch?v=tDWl72Eam0A The History and Sounds of the Best Kept Overdrive Secret in the Pedal Industry (Pedal Zone)] • [https://www.youtube.com/watch?v=Zn33dbZWevA Could this be the ultimate overdrive pedal?] • [https://www.youtube.com/watch?v=x3XwlfNGFgc Why Do The Pros LOVE The Original 90's Nobels?] • [https://www.youtube.com/watch?v=Afm3js3Nk_w Sweetwater] • [https://www.youtube.com/watch?v=WjCVnFLwP9k That Pedal Show] • [https://www.youtube.com/watch?v=-e2XtLMFRtY Reverb] • [https://www.youtube.com/watch?v=Ep001Ok8b1I ProGuitarShop] • [https://www.youtube.com/watch?v=2lXN7obmJoQ Brett Kingman] • [https://www.youtube.com/watch?v=jcwJ94ejw_c Mike Hermans]

==OCTAVE DISTORTION (Tycobrahe Octavia)==

[[file:x_Octavia.jpg|175px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-octave-dist-based-on-tycobrahe-octavia.123445/ Original forum thread]

The story is that Roger Mayer, technician for Jimi Hendrix, designed a fuzz pedal for him which added a ringing upper octave, using frequency doubling (“Octavio”). Hendrix played it on songs like “Purple Haze” and “Who Knows”. When a prototype broke down while on the road, Hendrix took it to Tycobrahe Sound Company for repairs. After Jimi passed away, Tycobrahe started selling the design as the Tycobrahe Octavia without the consent of Roger Mayer. Different versions of the story exist. Tycobrahe also built the PedalFlanger and ParaPedal pedals. All these devices are extremely rare, sought-after, and very expensive. Tycobrahe went out of business and the trademark now belongs to [http://chicagoiron.com/ Chicago Iron], who produce the $350 Octavian and other Tycobrahe designs.

<blockquote>''"The Octavia was an effects pedal designed for Jimi Hendrix by his sound technician, Roger Mayer. It reproduces the input signal from a guitar one octave higher and/or lower in pitch, and mixes it with the original and added distortion fuzz. It reproduces the input signal from a guitar one octave higher and/or lower in pitch, and mixes it with the original and added distortion fuzz. The effect was used by Jimi Hendrix and can be heard in guitar solos on the song "Purple Haze". Hendrix preferred to call the device the “Octavio”, and it is often referred to as such. After Hendrix's death in 1970 one of the original Octavias became the basis for the redesigned "Octavia", manufactured by Tycobrahe Sound Company in Hermosa Beach, California, during the mid-1970s. A limited number of the devices were produced, and today a used one in good condition sells for over $1,000 on eBay. Stevie Ray Vaughan owned nine of these devices."'' [https://en.wikipedia.org/wiki/Octavia_(effects_pedal) Wikipedia]</blockquote>

[http://chicagoiron.com Tycobrahe history]

<blockquote>''“Our pedal, by itself, should give you a strong "fuzz face" like sound on the lower neck positions, and have a hint of octave doubling as you go up the neck, combined with a ring modulated sound. After the 12th fret especially on the G B and E strings, the octave becomes even more pronounced. You may already know about the need to use the neck pickup, with the guitar tone knob rolled all the way off to start. The pedal will sing and bloom octaves on the higher registers when followed by a high output distortion pedal, (not all buffered output pedals will do) or an amp drive channel that is setup for distortion that has a good deal of sustain, like a Marshall super lead gets when turned all the way up. Then using the neck pickup and tone knob rolled off, switch on the Octavian. Set the Octavian pedal volume knob to achieve unity gain with your amp's clean channel and the pedal boost knob all the way counter clockwise, or off. Depending on the pickups, anywhere from the 10th fret and up you should be able to play a note and the pedal will allow the fundamental note to sound and then bloom into the octave note. By adjusting the pedal boost and the volume knob of the guitar you can go from blooming octave to double note (chiming) octave to flute like octave only. It is a system, guitar Octavian, distorted pedal or amp, guitar output signal level and tone control that make this happen. It is the same with all the octave up pedals. Forgive me if you already know how to make the octave pedals sing on your setup, as there is only a certain way that it goes. At this time you should be able to produce a light quieter octave and ring modulator sound when using only the Octavian in the signal going to your clean amp channel. Many references to this tone are on any Band of Gypsies album. By switching on to your amp's gain channel, or switching on a fuzz/distortion pedal after the Octavian will produce a singing sustain that blooms into a clear ringing octave. Octave is not all it can do in this position. Chords in the lower positions are huge and fat. Not just for playing the Hendrix and Stevie Ray Vaughan set. This pedal blows many other distortion pedals off the stage when it comes to bottom end drive. When you get your Octavian pedal fitted properly in your setup, the fun really begins. When used either way the Octavian pedal is very touch sensitive. It responds to your playing style. Pick light and the octave comes out earlier. Pick heavy and the fundamental note sustains longer. Same with the guitar volume knob, turn down the volume for more octave. By experimenting with the guitar's tone knob, you can produce many different sounds and octave "sweet spots".”'' [http://chicagoiron.com/ Chicago Iron]</blockquote>

[http://www.roger-mayer.co.uk/octavia.htm Roger Mayer] has produced his own version of the pedal since the ‘80s:

<blockquote>''“The OCTAVIA is probably our most famous and distinctive creation. This guitar effect was designed in early 1967 and featured on "Purple Haze" and "Fire" by Jimi. Its unique tones can also be heard on such tracks as "One Rainy Wish", "Little Miss Lover", "Little Wing", "Machine Gun" etc. The OCTAVIA produces a sound that is an octave higher than the note you are presently playing. This doubling effect is accomplished through electronic mirror imaging techniques that are program sensitive and also respond to the feedforward inputs of the player. The electronic circuitry is analogue in design and will react faithfully to all the subtleties and harmonic overtones from the guitar. The effect produced is very unique but human in quality. The unit that is manufactured today is representative of the latest evolution of Octavia that Jimi used and contains the feedforward and gating effect that my earlier evolutions lacked. The modern clones today often copy the Tycobrahe unit that in fact was a rip off of my earlier 24 volt versions. These units were not designed to work optimally with 9 volts and in fact you would be buying a clone of a copy so it makes sense to buy a unit from the man who invented it. Electronically the OCTAVIA is an analogue circuit with the properties of a frequency doubler, envelope generator and amplitude modulator with addition frequency shaping filter circuits. The effect produced is subtle to wild depending on the settings used and will respond to the attack of the player. A clean tone from the guitar with say the tone rolled control rolled off will produce "ring modulated" overtones that characterise the solo to "Who knows". The sound is tangibly different if a fuzz unit is in front of the Octavia: an upper octave double is created, clearly demonstrated in the solo to "Purple Haze". The bright harmonics are more controllable if the neck pickup is selected and the tone control set to roll off the treble. The effect really comes into its own on the top E and B strings from the 7th fret up. A clean and precise picking style is essential with particular attention to accurate fretting techniques. Jimi placed the Octavia after a fuzz and wah unit in most cases so it would react to the combined effects of both the wah and one or more fuzz boxes. It is important to experiment with how much signal you are driving the Octavia with as this has a great influence on the sound produced.”''</blockquote>

Fulltone is another company claiming to have designed an exact copy of the original Tycobrahe Octavia (a copy of a copy). His [https://www.fulltone.com/products/octafuzz-2 Octafuzz] (around $150) is used by Joe Satriani. And there’s the [http://www.voodoolab.com/proctavia.htm Proctavia from Voodoo Labs].

[http://fuzzcentral.ssguitar.com/octavia.php Fuzz Central] • [https://en.audiofanzine.com/fuzz-pedal/editorial/articles/legends-the-history-of-the-great-fuzz-pedals.html#a-href-octaver-harmonizer-whammy-roger-mayer-octavia-roger-mayer-octavia-1967-a The History of the Great Fuzz Pedals] • [https://www.guitarplayer.com/gear/classic-gear-roger-mayers-octavia-pedal Roger Mayer’s Octavia]

The pedal adds an octave on top of the played note plus fuzz. The recommended way is to use the neck pickup, roll off tone on the guitar for best tracking and removing the fundamental note, and play single close to the 12th fret.
A low-gain Octavia into a clean amp sounds like a Ring Modulator effect. It's mostly used in combination with a separate fuzz, either before or after, or into a slightly dirty amp. The models are featured in some factory presets, [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets search this wiki page] for “Octavia”.

The Univox Super-Fuzz (also modeled) is another octavia-type of fuzz.

The pedal has two controls: Volume and Boost (amount of fuzz, model: Drive)).

[https://www.youtube.com/watch?v=G1qtYYOAiw8 Jimi Hendrix: Who Knows] • [https://www.youtube.com/watch?v=G-4lKcrBVcQ Tycobrahe Octavia] • [https://www.youtube.com/watch?time_continue=1417&v=HLoJzejazKU Classic Fuzz Tones: Where To Begin? (That Pedal Show)] • [https://www.youtube.com/watch?v=AStSeVDxEhs 1975 Tycobrahe Octavia] • [https://www.youtube.com/watch?v=5mqKUD2jm6E Octavio 60 Second Demo] • [https://www.youtube.com/watch?v=ZP2jTTj9xoE Fulltone Octafuzz II OF-2]

==OD 250 (DOD Overdrive Preamp 250: reissue)==

[[file:OD250.jpg|160px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-hoodoo-drive-based-on-voodoo-lab-overdrive.164477/ Original forum thread]

[https://en.wikipedia.org/wiki/DOD_Electronics DOD Electronics] (David Oreste Di Francesco) was a famous American manufacturer of pedals and other effect devices, a competitor of MXR at the time. [https://www.digitech.com DigiTech] started as a division of DOD. These days the DOD brand is carried by DigiTech. In advertisements DOD referred to itself as “America’s Pedal”.

The silicon diode-based [https://digitech.com/dp/overdrive-preamp-250/ DOD 250 Overdrive Preamp pedal] was released around the late ‘70s. In fact, it’s one of the first overdrive pedals. Its circuit originally was based on the MXR Distortion + (also modeled by Fractal Audio), but it's a little less fuzzy / raspy. It builds on the LM741 op-amp. It says “preamp” on the pedal, but it’s not a preamp as in an amplifier. The pedal keeps the middle frequencies flat, rolls off bass, boosts highs and adds some compression when turning up gain. This works very well with an amplifier on the verge of breakup or already overdriven. The ’78 “gray spec” OD 250 is the most sought-after version. DOD changed to a yellow enclosure in 1980. Later versions were named FX50. A reissue was released in 2013 ([https://tonereport.com/reviews/dod-overdrive-preamp-250 here's a review]).

[https://www.jhspedals.info/overdrive-preamp JHS Pedals' Overdrive Preamp] is a replica of the very first ’74 version (before the “gray spec”, without “250” in the name). [https://www.earthquakerdevices.com/gray-channel EarthQuaker’s Gray Channel] is a clone of the original OD 250. Voodoo Lab’s Overdrive (also modeled by Fractal Audio) was based on the 250. DOD made a signature version for Yngwie Malmsteen, the DOD YJM308, named after a Ferrari 308 (read more about it on [http://www.analogman.com/dodmod.htm AnalogMan.com]). Fender’s Yngwie Malmsteen Overdrive pedal is also based on the DOD 250. More about 3rd party clones of the DOD 250 on [https://reverb.com/news/the-legacy-of-the-dod-250-which-250-is-right-for-you Reverb.com]. And much more background information in [https://www.youtube.com/watch?v=lx3GsD2XBZU this JHS Pedals video].

<blockquote>''“The legendary analog DOD Overdrive Preamp 250 is back, with over 40 years of history and experience behind it. The new 2013 version of the legendary DOD 250 captures all of the classic tone and wild heart of the original but in no way tames its performance. The 250 is better than ever before with true bypass, a crisp blue LED indicator, gobs of output, and modern 9V DC power supply input. Redesigned with a lighter aluminum chassis, sleek yellow metallic flake and flat black matte bottom paint job, the undefined DOD Overdrive Preamp 250 pedal is the perfect sonic foundation to carry on the legacy of DOD. The DOD Overdrive Preamp 250 (2013) has Gain and Level controls, like its predecessors. Gain controls the amount of distortion, from just a touch of grit to all-out grind. Level dials in some subtle body for “always on” performance or huge amounts of boost for boosting solos above a dense stage mix. With the Gain all the way down, crank up the Level to boost your sound and cut through during your solos. True bypass allows your guitar tone to remain pristine even when the new DOD 250 (2013) is off. This is a big difference from the original which would color your bypassed tone. The modern 9V DC power supply input make the pedal more pedalboard friendly.”'' [https://digitech.com/dp/overdrive-preamp-250/ Digitech] </blockquote>

The pedal’s controls are Gain (model: Drive) and Level. Turn them both up and run it into a dirty Marshall.

Fractal Audio has modeled the “gray spec” version as well as the reissue which has more gain.

[https://www.youtube.com/watch?v=lx3GsD2XBZU The Legend of the DOD 250 (JHS)] • [https://www.youtube.com/watch?v=7d8sFwcxkYM Reverb.com] • [https://www.youtube.com/watch?v=lCUk-l4VsmI Brett Kingman] • [https://www.youtube.com/watch?v=ZYWGUhjkItc 60 Cycle Hum] • [https://www.youtube.com/watch?v=hCMdhlPuklE DigiTech] • [https://www.youtube.com/watch?v=CSMtYsRgZ4o YJM308 Yngwie Malmsteen vs 250 Overdrive Preamp] • [https://www.youtube.com/watch?v=13NouN_n_3s ProGuitarShop] • [https://www.youtube.com/watch?v=Q9ExiOqrjxU Audiofanzine] • [https://www.youtube.com/watch?v=etiVDTNRdbM&t=556s Overdrives Under $100 (JHS)] • [https://www.youtube.com/watch?v=SVbceQGhbdM&t=104s Why You Need A Preamp (JHS)] • [https://www.youtube.com/watch?v=EtT2gGU-6fU&t=395s 1970’s Op-Amp Distortion (JHS)] • [https://www.youtube.com/watch?v=TEAkxW1ZvCk SD-1 vs TS808 vs DOD 250] • [https://www.youtube.com/watch?v=1yffw8pa0fM Are you making this mistake with OD250 or Distortion+? (Wampler)]

==OD 250 GRAY (DOD Overdrive Preamp 250: original)==

[[file:x_OD250.jpg|235px]]

See above.

==OD-ONE OVERDRIVE (BOSS OD-1 Over Drive)==

[[file:OD-1.jpg|150px|left]]

The legendary '77 yellow Over Drive OD-1 was BOSS' first compact pedal and possibly the first overdrive pedal on the market, following the fuzz wave and preceding the Tube Screamer. It featured innovations such as a battery compartment, a LED and electronical switching. The OD-1 features asymmetrical clipping (unlike the Tube Screamer) using a quad op amp. It was the first to mix the clipped signal with the original signal, maintaining dynamics. The OD-1's gain is light and pleasant and cuts all bass. The OD-1 was discontinued in 1985 and followed by the BOSS SD-1, meant to compete with the Ibanez Tube Screamer. The OD-1 has been reissued once, as part of [https://www.boss.info/us/products/box-40/ BOSS' 40th Anniversary Box Set (limited edition)]. The "Turbo" OD-2 (mid '80s - 1994) expanded the range of the pedal to distortion. BOSS went back to basics with the [https://www.boss.info/global/products/od-3/ OD-3] (1997 - now), although it sounds different from the original (less mid-heavy). The BOSS digital OD-1X is a totally different pedal, not a reissue.

The OD-1 has Level and Over Drive knobs, no Tone. It doesn't provide much gain. It's a staple piece for blues players.

[https://electricdruid.net/designing-a-classic-overdrive/ Electric Druide] • [https://www.analogman.com/od1.htm AnalogMan]

[https://www.youtube.com/watch?v=kWiqALXU5U4 Analog Man's OD-1 Vintage Chip Mod] • [https://www.youtube.com/watch?v=VLcyeAsGFjc OD-1 vs. SD-1] • [https://www.youtube.com/watch?v=z2YkRazrxcU OD-1 & SD-1 vs Ibanez TS808 & TS9] • [https://www.youtube.com/watch?v=SgDVyNHdN9I Vintage Boss OD-1 Overdrive] • [https://www.youtube.com/watch?v=-fTGox-dD7A Different Boss OD and SD Sounds] • [https://www.youtube.com/watch?v=euQuxNMWAkg OD-1 vs SD-1] • [https://www.youtube.com/watch?v=otkW_q0_VIU&t=662s Diode-Based Overdrive and Distortion Effects] • [https://www.youtube.com/watch?v=PJrx7rLzxlk OD-2 (Leon Todd)] • [https://www.youtube.com/watch?v=BE1gfS2XP_4 TheToneShack] • [https://www.youtube.com/watch?v=Zg6JYTbt0d4&t=629s BOSS Is Best (JHS)] • [https://www.youtube.com/watch?v=dMpE7o0_6JA Boss Overdrive Pedals Explained (Wampler)] • [https://www.youtube.com/watch?v=kMiR-0aYOqI OD-1 vs SD-1 vs OD-1X]

==PI FUZZ (Electro-Harmonix Big Muff Pi, current)==

[[file:x_Pi.jpg|185px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-pi-fuzz-based-on-electro-harmonix-big-muff-pi.123477/page-2 Original forum thread]

The Big Muff is one of the most popular fuzz boxes ever. Many famous players used one at some time in their careers: Carlos Santana, David Gilmour ([https://www.youtube.com/watch?v=_FrOQC-zEog&t=305s “Comfortably Numb”]), Smashing Pumpkins ([https://www.youtube.com/watch?v=q-KE9lvU810 “Cherub Rock”]), Jack White, Jimi Hendrix, Black Keys, etc. It wasn’t used on “American Woman” as often assumed, but you can hear it on [https://www.youtube.com/watch?v=nooeMrCws-A "Goodbye to Love”] (Carpenters). The Big Muff made a comeback in the Stoner and Doom rock scenes. The pedal cascades a fuzz circuit into additional gain stages. This results in long and smooth sustain and a dark tone. Less spitty when compared to other fuzzes. Because of all that saturation, it sounds best into a clean amp. It can be used with a bass too. Electro-Harmonix released the Big Muff Pi with its four silicon transistors in 1969. Its owner Matthews states that this points to the muffled tone, but there are other explanations of a more naughty nature.

<blockquote>''“Hendrix and Santana were among the first to get a piece of the Pi, and for over 40 years the Big Muff Pi has been defining the sound of rock guitar. Revered by contemporary guitarists and rock legends for its rich, creamy, violin-like sustain, from Pink Floyd to The White Stripes, everyone still wants a piece of the Pi!”'' [https://www.ehx.com Electro-Harmonix]</blockquote>

<blockquote>''“The Big Muff Pi (π), often known simply as the Big Muff, is a fuzzbox produced in New York City by the Electro-Harmonix company, along with their Russian sister company Sovtek, primarily for use with the electric guitar. It is used by bassists as well due to the Big Muff's low-end frequency response.”'' [https://en.wikipedia.org/wiki/Big_Muff Wikipedia]</blockquote>

EHX went out of business in the ‘80s. Its owner Matthews relaunched it from Russia (as: Sovtek) in the ‘90s and took the company back to the USA. There’s an interview with Matthews about this period in the book [https://bjooks.com/products/pedal-crush-stompbox-effects-for-creative-music-making Pedal Crush – Stompbox Effects For Creative Music Making].

The Big Muff has seen many versions, as described [http://www.kitrae.net/music/big_muff_history.html here] and [http://www.bigmuffpage.com/ here], and new versions are still being released, below and above $100. The first version (aka Triangle or V1) and second version (aka Ram’s Head or V2) are generally considered to be the most sought-after, but the Russian edition is also popular. Many clones exist. [https://www.jhspedals.info/muffuletta JHS Pedals' Muffuletta] reproduces the sound of 5 versions of the Big Muff.

[http://www.electrosmash.com/big-muff-pi-analysis ElectroSmash] • [https://en.audiofanzine.com/fuzz-pedal/editorial/articles/legends-the-history-of-the-great-fuzz-pedals.html#a-href-fuzz-pedal-electro-harmonix-big-muff-pi-electro-harmonix-big-muff-pi-1969-a Audiofanzine] • [https://reverb.com/nl/news/how-to-use-big-muffs-to-dial-in-the-tone-of-five-famous-guitarists How to Use Big Muffs to Dial-In the Tone of Five Famous Guitarists] • [https://www.ultimate-guitar.com/articles/features/brief_history_of_fuzz_effect_and_5_most_important_vintage_fuzz_pedals-94813 Brief History of Fuzz] • [https://www.gitarrebass.de/equipment/test-ehx-op-amp-triangle-green-russian-big-muff/ Gitarre & Bass (German)] • [https://www.tonehome.de/electro-harmonix/big-muff-π/ Schematic] • [https://www.ehx.com/topic/big-muff-versions-and-tone-differences/ EHX forum] • [https://pedaltown.nl/en/a-brief-history-of-the-electro-harmonix-big-muff Pedal Town] • [https://anasounds.com/big-muff-history/ Anasounds] • [https://www.guitarcenter.com/riffs/buying-guides/amplifiers--effects/electro-harmonix-big-muff-guide-history?srsltid=AfmBOor2cdHk91ZMNjpELVupr7gHXsKNwYTfywOrPArXLaO3xWpy_47n Guide to the Electro-Harmonix Big Muff]

The pedal has three controls: Volume, Tone and Sustain.

In current Fractal Audio firmware, the PI Fuzz model is based on the current version. There are separate models of the Triangle, Russian and Ram's Head pedals. [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-27-03-public-beta.209954/page-4#post-2624245]

The models have a “Wicker” switch which removes the feedback capacitors, and a “Tone” switch which allows bypassing the tone circuitry.

The Muff typically has a scoop around 1000 Hz. To prevent the model from disappearing in the mix, turn up the mids, using the tone controls or the graphic EQ in the Drive block. Another trick is to precede the Big Muff with an overdrive. The PI Fuzz is featured in some factory presets. [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets Search this wiki page] for “PI Fuzz”.

[https://www.youtube.com/watch?v=nWK0XnX3uZs Peter Stroud] • [https://www.youtube.com/watch?v=hnsQRpgYmaE Jack White in “It Might Get Loud”] • [https://www.youtube.com/watch?v=JqK5zbLEZ0I Reverb.com] • [https://www.youtube.com/watch?v=dfroxFpUYlE Comparing 6 varieties] • [https://www.youtube.com/watch?v=NXcpqldmg_8 ProGuitarShop] • [https://www.youtube.com/watch?v=BWm-ROMiEHo Big Muff Comparison] • [https://www.youtube.com/watch?v=A7vapqY6nbI Gearmanndude] • [https://www.youtube.com/watch?v=AZyx7Z4tq_c&t=92s Triangle Big Muff Reissue] • [https://www.youtube.com/watch?v=XTGmfsKHcXo&t=658s History Of Guitar Distortion (JHS)] • [https://www.youtube.com/watch?v=9OaLT-wVspk&t=194s Vintage vs Reissue (JHS)] • [https://www.youtube.com/watch?v=Id_tOY5uryU blondegraymey] • [https://www.youtube.com/watch?v=otkW_q0_VIU&t=1043s Diode-Based Overdrive and Distortion Effects] • [https://www.youtube.com/watch?v=gLR1yA8rk2U Dave Webb]

==PI FUZZ - TRIANGLE (Electro-Harmonix 1971 Big Muff Pi Triangle)==

See above.
Based on a 1971 “Triangle” Big Muff PI. Includes the Tone Wicker mods.

[https://www.youtube.com/watch?v=nCbzKsmTsEk EHX] • [https://www.youtube.com/watch?v=HcEuC4Difck Sam Goffen] • [https://www.youtube.com/watch?v=dMixp1YE5SE Middle Aged Gear Junkie]

==PI FUZZ - RAM'S HEAD (Electro-Harmonix '70s Big Muff Pi Ram's Head)==

See above.
Based on a mid-70’s “Ram’s Head” Big Muff PI. Includes the Tone Wicker mods.

The Ram's Head was the 'inspiration' for the 1973 Colorsound Tone Bender, also modeled by Fractal Audio.

<blockquote>''"The tone control on the Ram's Head does is awesome. Change it up when you record doubles or triples for tones with the bulk and presence of a giant Pleistocene mammal. Tip 2: Turn up Low Cut (EQ2 page) on this model and it becomes a bit more forgiving of the thumps you feed it.”'' [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-27-03-public-beta.209954/page-5#post-2624347 Fractal Audio]</blockquote>

[https://www.youtube.com/watch?v=n7ukFKUQj0g Jack Fossett] • [https://www.youtube.com/watch?v=zsxsYtxM6Gc Premier Guitar] • [https://www.youtube.com/watch?v=pfbir_FZ1wI Gilmourish]

==PI FUZZ - RUSSIAN (Electro-Harmonix Russian Big Muff Pi)==

See above. Based on a "Russian” Big Muff PI. Includes the Tone Wicker mods.

<blockquote>''"It has a much different sound. More bassy and mellower.”'' [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-27-03-public-beta.209954/page-9#post-2625802 Fractal Audio]</blockquote>

[https://www.youtube.com/watch?v=1ciNQkFLv6E Beers N Gears] • [https://www.youtube.com/watch?v=keefS_iaqbM Reverb] • [https://www.youtube.com/watch?v=lEBc0kIzl2k Guitologist]

==PLUS DISTORTION (Distortion +)==

[[file:x_Plus.jpg|150px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-plus-dist-based-on-mxr-distortion.123519/ Original forum thread]

MXR, now owned by [http://www.jimdunlop.com/products/electronics/mxr Jim Dunlop], was one of the largest effects manufacturers in the ‘70s and ‘80s. Several of their products are now considered classics: Dynacomp, Phase 90 and 100, Flanger, etc.
The Distortion + (M104) was released in 1973. The “+” refers to the purpose of this pedal: adding more distortion to an already overdriven amp. Famous users include Randy Rhoads, Steve Vai (in the movie [http://www.vai.com/answers/ “Crossroads”]) and Radiohead’s Thom Yorke. Just like MXR’s Phase 90, early “script logo” versions of the pedal are appreciated more than the later “block logo” version. The current version costs around $80. It was MXR’s second pedal release and the first distortion pedal based on an op-amp, although there’s [https://www.youtube.com/watch?v=EtT2gGU-6fU some debate]. The pedal’s hard-clipping distortion is raspy and loose, almost fuzzy at high gain settings, like overloading the inputs of a console. The circuit is said to be like that of the DOD 250 (also modeled by Fractal Audio), although the sound is different.
'
<blockquote>''“This little yellow box is responsible for those great distortion sounds heard on so many classic recordings. Set the Distortion control low and crank the Output knob to drive the front end of your amp for cool blues tones, or max out the Distortion knob for classic early ’80s hard rock tone. There still isn't any distortion unit on the market that sounds like the Distortion+. Germanium-powered, soft-clipped distortion. Go from warm, tubey overdrive to gnarly fuzz. Classic early ’80s hard rock tone.”'' [https://www.jimdunlop.com/mxr-distortion/ MXR]</blockquote>

<blockquote>''“The MXR Distortion + ("Distortion Plus") is a distortion pedal originally designed in the 1970s by MXR Innovations. As its name implies "distortion," it's a 'distortion' (parallel clipping) but has a rather mild sound. It has been cloned many times, most famously by the DOD 250 Overdrive (a distortion). The pedal uses a single op-amp and a pair of germanium diodes to ground (parallel-push) for clipping in a very simple configuration with only Output and Distortion controls, no tone control; the pedal uses no discrete transistors. Turning up the Distortion control increases the amount of distortion and at the same time cuts some bass from the signal. This pedal is perhaps best known for its crunchy heavy metal sound that was featured by Randy Rhoads in his work with Ozzy Osbourne. Jerry Garcia of the Grateful Dead used this pedal exclusively for distortion in the late 1970s. Bob Mould of Hüsker Dü also used the Distortion + as part of his trademark guitar sound. Dave Murray of Iron Maiden has used Distortion + since the early 1980s. Thom Yorke of Radiohead has included the + for many of his signature distortion sounds, using a variety of guitars to achieve various tonal options.”''
[https://en.wikipedia.org/wiki/MXR_Distortion_%2B Wikipedia]</blockquote>

[https://www.electrosmash.com/mxr-distortion-plus-analysis Electrosmash] • [https://www.tonehome.de/mxr-innovations/distortion/ Tonehome]

The pedal’s controls are Output and Distortion. The pedal works best into an amplifier that's on the verge of breakup or already overdriven. Try Drive at 7 and Level at 8.

<blockquote>''"It's not a boost. It's a very simple distortion circuit with no output buffer. Typically you need to turn the Output knob up quite a bit.”'' [https://forum.fractalaudio.com/threads/plus-distortion-broken-fw19-05.182243/post-2236624 Fractal Audio]</blockquote>

[https://www.youtube.com/watch?v=2GLMhHthq3M Dunlop] • [https://www.youtube.com/watch?v=L5q4KR5PVvY ProGuitarShop] • [https://www.youtube.com/watch?v=6JW12COqGmc Brett Kingman] • [https://www.youtube.com/watch?v=X6cykKMbS-Q MXR Distortion plus vs vintage] • [https://www.youtube.com/watch?v=jhSMTVyXPQo Dweezil Zappa] • [https://www.youtube.com/watch?v=XTGmfsKHcXo&t=724s History Of Guitar Distortion (JHS)] • [https://www.youtube.com/watch?v=EtT2gGU-6fU&t=145s 1970’s Op-Amp Distortion (JHS)] • [https://www.youtube.com/watch?v=ZTp9zfMUmAk&t=271s How MXR Changed Pedals (JHS)] • [https://www.youtube.com/watch?v=pO9ye1D3Gj4 Jack Fossett] • [https://www.youtube.com/watch?v=zptsemsFMpM shnobel] • [https://www.youtube.com/watch?v=1yffw8pa0fM Are you making this mistake with OD250 or Distortion+? (Wampler)]

==RAT DISTORTION (Pro Co RAT)==

[[file:x_RAT.jpg|175px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-rat-dist-and-fat-rat-based-on-pro-co-rat.123168/ Original forum thread]

The [https://www.ratdistortion.com RAT] is a famous distortion pedal by Pro Co. The black box is easily recognizable. Famous users include David Gilmour, Noel Gallagher, Arctic Monkeys, Jeff Beck, Radiohead, and Kurt Cobain. Nuno Bettencourt never plays [https://www.guitarworld.com/news/nuno-bettencourt-most-important-pedal without a RAT]; his signature Randall amp had one built-in. The RAT was a sign of changing times, with guitar players looking for ways to get more distortion than the MXR Distortion + (also modeled by Fractal Audio) delivered. The RAT was born out of an accident, according to [https://reverb.com/news/andys-vintage-picks-video-the-1988-proco-rat-2 Reverb.com]. A wrong transistor was connected to a circuit board. The RAT can sound harsh and into-your-face. The passive Filter knob is crucial to its tone. In the first versions it was a conventional tone control, which was changed to a treble roll-off later. Make sure to experiment with it in the model but be aware: it works the opposite way of the real pedal. With a clean amp, the RAT can also sound a little fuzzy, especially on the lower notes. Fractal Audio’s model of the 1981 Inventions DRV pedal may be a better match with real clean amps. Because of its hybrid fuzz/distortion character, it’s sometimes referred to as the counterpart of the Big Muff (also modeled by Fractal Audio). Where the Big Muff covers the fuzzy spectrum, the distortion wins the battle in the RAT. It’s also said that the RAT is not that far off from the Boss DS-1 (also modeled by Fractal Audio). The RAT seems to sound best through mid-heavy amplifiers like VOX, because of the pedal’s scooped frequency curve. It also works on bass, as proven by Nirvana.

Pro Co produced many versions of the RAT, including the popular 1983 “white-on-black” version, ’87 RAT 2, ’89 Turbo RAT, FAT RAT, You Dirty RAT, BRAT, Deucetone RAT and others. Many other pedal manufacturers, including Wampler and JHS, have build clones or RAT-inspired pedals. The $250 [https://1981inventions.com/shop 1981 Inventions DRV pedal], also modeled by Fractal Audio (“MCMLXXXI DRV”), is a boutique clone of the RAT with less gain, which sounds better with clean amps than the RAT does.

[https://www.ratdistortion.com RAT website] • [https://reverb.com/news?category_name=Tone+Report Coolest Versions of the ProCo RAT (Tone Report)] • [https://www.electrosmash.com/proco-rat Pro Co Rat Analysis (ElectroSmash)] • [https://www.ultimate-guitar.com/articles/features/is_this_the_best_distortion_pedal_of_all_time_history_of_pro_co_rat-114968 Is This the Best Distortion Pedal of All Time?] • [https://www.youtube.com/watch?v=QfwpClT_26E History of the ProCO RAT Pedal and Myth Debunked (JHS)] • [https://www.youtube.com/watch?v=0B-yghZZlNw RAT clones You’ve Never Seen Before] • [https://www.gitarrebass.de schematic].

<blockquote>''“The RAT is a guitar effects pedal produced by Pro Co Sound. The original RAT was developed in the basement of Pro Co's Kalamazoo, Michigan facility in 1978. Numerous variations of the original RAT pedal are still being produced today. The basic RAT has changed in appearance over the years, but its tone has remained largely the same. Pro Co has also introduced tonal variations of the RAT, including the Turbo RAT, and You Dirty RAT, among others. The Pro Co RAT became very popular in the early 1980s, thanks in part to fame gained by its use by several artists. It is a distortion pedal with a quite simple circuit, which can be broken down into four simpler blocks: distortion stage, tone control, output stage and power supply. The design is based around a single opamp, originally the Motorola LM308 (switched to Texas Instruments OP07DP around 2002-2003). The distortion is produced using a variable gain circuit with diodes shorting the output to ground to produce hard clipping of the input waveform. (...) This construction method is similar to the Boss DS-1 distortion pedal, although there are major differences between the two circuits. A major difference is the opamp used (the LM308), known for its poor slew rate; it largely accounts for the sonic difference between the two pedals.”'' [https://en.wikipedia.org/wiki/Pro_Co_RAT Wikipedia]</blockquote>

Nuno's RAT:

[[file:Nuno.jpg|150px]]

The classic RAT pedal has three knobs: Distortion, Filter (roll-off filter), Volume. Nuno sets the Distortion really low.

The op-amp-based Rat Distortion model lends itself well for experimenting with different clip types, because the clipping stage isn’t affecting or affected by other parts of the circuit. This model is also often used to soften the Synth block, adding sustain and smoothness. Fractal Audio’s Fat Rat model is based on [https://en.wikipedia.org/wiki/Light-emitting_diode LED (light-emitting diode) clipping]. Those little lights can be used for intentional signal clipping, creating distortion. LEDs have a lot of headroom and are less fizzy and louder than other diodes.
[https://www.youtube.com/watch?v=bifKfe04TBc Video: test different clipping modes for diy pedals]

The RAT is featured in some factory presets. [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets Search this wiki page] for “RAT”.

[https://www.youtube.com/watch?v=n7bjGcZoXTQ Vintage Rat vs Newer Rat (shnobel)] • [https://www.youtube.com/watch?v=ub9KjynPa6Y That Pedal Show] • [https://www.youtube.com/watch?v=YK_PTQJqRrI 1988 ProCo Rat 1] • [https://www.youtube.com/watch?v=cd5fx4GiVcw Big Box Rat 1983 vs Rat 1986 (shnobel)] • [https://www.youtube.com/watch?v=DUuAIpT_hhg 1985 RAT vs JHS Angry Charlie (shnobel)] • [https://www.youtube.com/watch?v=jTZExCysMIc 1986 RAT with Fender Jazz Bass through Ampeg SVT] • [https://www.youtube.com/watch?v=ruPLYTl3QM8 1988 ProCo Rat 2 (Reverb)] • [https://www.youtube.com/watch?v=C86-5ln02do gearmanndude] • [https://www.youtube.com/watch?v=Tu6ko-GBaKE gearmanndude: JHS ProCo RAT2 Rat Pack Mod] • [https://www.youtube.com/watch?v=XTGmfsKHcXo&t=763s History Of Guitar Distortion (JHS)] • [https://www.youtube.com/watch?v=skEYdG8MTto&t=682s 10 Rare Pedals (JHS)] • [https://www.youtube.com/watch?v=EtT2gGU-6fU&t=608s 1970’s Op-Amp Distortion (JHS)] • [https://www.youtube.com/watch?v=B_jtDX1_FZg Every RAT Pedal You’ll Ever Need (JHS)] • [https://www.youtube.com/watch?v=QfwpClT_26E History of the ProCO RAT Pedal and Myth Debunked (JHS)] • [https://www.youtube.com/watch?v=zBGKdnlh4Ws Let’s talk about the Rat Distortion pedal (Wampler)] • [https://www.youtube.com/watch?v=otkW_q0_VIU&t=929s Diode-Based Overdrive and Distortion] • [https://www.youtube.com/watch?v=ULnZThSeRnY Original versus the Others] • [https://www.youtube.com/watch?v=2KpnEfk6DhY 4 Tips How You Can Use The ProCo Rat 2 Distortion] • [https://www.youtube.com/watch?v=yFHcmQ5biYA Ola Englund] • [https://www.youtube.com/watch?v=iMk8UA_A58o] • [https://www.youtube.com/watch?v=Xn5XAwCScnc Revv Amps] • [https://www.youtube.com/shorts/WOIJpO8SfbU Michael Nielsen] • [https://www.youtube.com/watch?v=4XHSTm5Qgpc John Cordy]

==SDD PREAMP (Korg SDD-3000 preamp)==

[[file:x_SDD.jpg|625px]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-sdd-preamp-based-on-preamp-in-korg-sdd-3000.123551/ Original forum thread]

When Fractal Audio added the SDD Preamp model, it was public knowledge that The Edge (U2) had started using Fractal Audio gear. The Edge is known for being a fan of the Korg SDD-3000 digital delay. There might be some correlation between The Edge’s use of Fractal Audio gear and the addition of this model. The SDD-3000 is a low-resolution (13-bit) 19” op-amp digital delay, released in 1982. Its embracement by The Edge contributed greatly to its popularity. The built-in preamp has a character of its own. The Edge reportedly runs the SDD-3000 even without its delays, just for its warm-sounding preamp. There are no specific preamp controls on the original device, except for an input level control and attenuator switches. Unlike the preamp in the Echoplex delay, there aren't many clones of the SDD-3000’s preamp. The SDD-3000 has been [http://www.korg.com/us/products/effects/sdd3000_pedal/ reissued by Korg as a pedal], with the help of Dallas Schoo (pronounce: "shoe"), The Edge’s guitar tech. The pedal received mixed reviews, but Peter Frampton used it.

[http://www.korg.com/za/news/2014/1101/ SDD-3000 preamp pedal] • [http://www.florian-anwander.de/korg_sdd3000/Korg_SDD-3000_ServiceManual.pdf service manual]

Fractal Audio’s SDD Preamp model can be used as a clean boost. Its main attraction is its ability to compress the signal a little, add some sparkle to the sound without getting harsh and tighten the bass a bit. It enhances the tone, adds warmth and chime, and makes highs jump out and tingle, reminiscent of The Edge’s signature tone. You can also use it for distortion, if desired, by cranking the Drive control. The model is featured in some factory presets. [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets Search this wiki page] for “SDD”.

[https://www.youtube.com/watch?v=ZQC9aOgEsts Dallas Schoo (U2 guitar tech)] • [https://www.youtube.com/watch?v=QmdIzWoP11k mick3b1g] • [https://www.youtube.com/watch?v=fQaeENsPc-s Korg SDD-3000 Preamp] • [https://www.youtube.com/watch?v=8gGshVoH7B0 schnobel]

==SHIMMER DRIVE (custom model)==

[[file:logo.jpg|150px|left]]

Fractal Audio has created a couple of custom models. These virtual drives have no real-life equivalents. They solely exist within Fractal Audio’s processors, implementing Fractal Audio’s ideas and improvements on existing pedals. The “silicon” Shimmer Drive is such a model. Its purpose is to boost amp models which are based on amplifiers without a master volume, like certain amplifiers made by Vox, Fender, and Marshall. It has gained a lot of popularity among Fractal Audio users. It very transparent and works well with both clean and dirty amps, just set Drive accordingly. Also, this drive model requires less CPU power than many other models. Start with the Drive control set really low, compensate with Level and turn down Tone a little.
The model is featured in some factory presets. [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets Search this wiki page] for “Shimmer Drive”. The model is also available as an input boost type in the Amp block.

<blockquote>''"The Shimmer Drive is my own creation. It is primarily intended to be used as a boost for Non-MV amps like AC-15/30's, Fenders and Plexis.”'' [https://forum.fractalaudio.com/threads/axe-fx-ii-quantum-rev-7-01-firmware-release.125328/post-1491304 Fractal Audio]</blockquote>

==SHRED DISTORTION (Marshall Shredmaster)==

[[file:x_Shred.jpg|200px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-shred-dist-based-on-marshall-shred-master.123589/ Original forum thread]

In the ‘90s Marshall released the Shredmaster pedal (together with the Drivemaster and Bluesbreaker pedals). By today’s standards it isn’t really a metal pedal for shredders. But it is high gain. Marshall was aiming for the sound of a Marshall JCM-900 amplifier. It hasn’t received as much appreciation as Marshall’s Bluesbreaker pedal from the same era, but it did become more popular after Radiohead’s Johnny Greenwood had started using it. Reportedly, it’s used in the chorus of [https://www.youtube.com/watch?v=XFkzRNyygfk “Creep”]. It was also used by Blur, Supergrass and Manic Street Preachers.

[http://www.guitartoneoverload.com/2010/03/04/discontinued-greats-the-marshall-shredmaster/ Guitar Tone Overload: Discontinued Greats] • [http://honestdistortion.com/pedals/marshall-shredmaster/ Honest Distortion] • [https://www.tonehome.de/marshall-amplification/shredmaster/ ToneHome]

The pedal has these controls: Gain, Bass, Treble, Contour (changes the character of the mids, scoops the tone) and Volume. The Contour knob is crucial. To get Metal Zone-type tones, crank it. Also, turn up gain and keep Level low.

In 2023 Marshall released a [https://marshall.com/amps/products/pedals/shredmaster series of reissues including the Shredmaster].

Fractal Audio's model is based on the original version.

[https://www.youtube.com/watch?v=zMhhlHDSzgo&t=219s Marshall Vintage Reissue Pedals] • [https://www.youtube.com/watch?v=jOmKB5EaIHs blondegraemey] • [https://www.youtube.com/watch?v=0LlH1rn65dY with an Engl Powerball] • [https://www.youtube.com/watch?v=e-tWRVd75Z4 The SuperFunAwesomeHappyTime Pedal Show!] • [https://www.youtube.com/watch?v=IsrHC3AGAEs Marshall Shred Master vs Boss MT-2 Metal Zone] • [https://www.youtube.com/watch?v=5bk4w8rrbZk&t=535s Marshall’s Greatest Pedals (JHS)] • [https://www.youtube.com/watch?v=UL-dFjJWNvg with a Fender Champ] • [https://www.youtube.com/watch?v=K32OWQjbcBM Guitar Center] • [https://www.youtube.com/watch?v=QQAdTF1BIo4 Guitar Bonedo] • [https://www.youtube.com/watch?v=7OMp4Q1e_9o Peach Guitars] • [https://www.youtube.com/watch?v=wTtqdZzclGY Ola Englund] • [https://www.youtube.com/watch?v=Q2rG3J9mYvU Pedal Pawn]

==SONIC DRIVE (Maxon/Ibanez SD-9 Sonic Distortion)==

[[file:x_SD9.jpg|160px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-sonic-drive-based-on-ibanez-sonic-distortion-sd-9.170292/ Original forum thread]

This pedal is from the same era and series as the Ibanez TS9 Tube Screamer. It’s a dual-diode op-amp distortion, not an overdrive, and can even cross into fuzz territory. It scoops the mids instead of boosting them, depending on the position of the Tone knob. It’s especially appreciated in the fusion scene, including Mike Landau, and Scott Henderson is sort of its ambassador. Ibanez released a modded version: SD9M. These days [https://maxonfx.com/collections/nine-series/products/sonic-distortion-sd-9 Maxon] manufactures the SD9 as part of their Nine Series. [https://www.buyanalogman.com/searchresults.asp?Search=sd9 Analog Mike] sells a modded version.

<blockquote>''"Since its original release in the early 80’s the Sonic Distortion has gained a huge cult following among tone connoisseurs, including the likes of guitar legends Scott Henderson and Mike Landau. Maxon’s current-production reissue captures all the magic of the original with the added benefit of true bypass switching. The SD-9 provides a smooth distortion that covers a wide range of Gain levels from mild overdrive through pseudo-fuzz. Regardless of the Gain setting, the SD-9 remains articulate and responsive to note dynamics, providing excellent sustain without crossing over into super-compressed Metal territory. The SD-9’s Tone knob has plenty of top end on tap, yet notes still retain a round, full-bodied tonality with the low end presence usually associated with amp distortion. The pedal’s midrange response is smooth and even – present without seeming spiked. Since its humble origins to its current place in the pedalboards of the stars, the Maxon Sonic Distortion has proven itself to be a timeless classic that has only improved with age."' [https://maxonfx.com/collections/nine-series/products/sonic-distortion-sd-9 Maxon]</blockquote>

<blockquote>''"It's sort of like a dist+ (your ross) with a big muff tone circuit. I like them a lot but the tone circuit loses all the low end if you turn up the tone knob, so most people leave the tone knob down. Or they can be modded to make the tone circuit better and also a midrange knob can be added to get rid of the scooped mids if desired."'' [https://www.buyanalogman.com/Maxon_SD_9_Super_p/am-maxon-sd-9-super.htm Analog Man]</blockquote>

<blockquote>''"The Maxon SD-9 is the best distortion pedal EVER made, period. It has the clarity and punch you get from a pedal, while retaining the low bass you get with amp distortion. The SD-9 is one of the rare pedals which sound equally great on both the neck and bridge pickups, whether they're humbucking or single coil. It's been a very important part of my tone for many years."'' Scott Henderson</blockquote>

[https://legendarytones.com/maxon-od-9-overdrive-and-sd-9-sonic-distortion/ Legendary Tones] • [https://www.gearnews.com/maxon-scott-henderson-sd-9sh-sonic-distortion-the-best-distortion-in-the-world/ Maxon Scott Henderson SD-9SH] • [https://www.thegearpage.net/board/index.php?threads/improved-maxon-sd-9.2238034/post-32214905 Graphs of the Tone knob settings by Analog Mike]

The pedal has the usual three controls: Distortion, Tone and Level. The Tone knob covers a very wide range, on the real pedal as well as in Fractal Audio’s "Sonic Drive" model. Turning it down is crucial because it avoids shrill tones and loss of bass (unless you want to use the pedal as a treble booster). Use the guitar’s volume and tone knobs to finetune the sound. Try this: Drive 2.25, Tone 2.75, Level 7.25. The model is featured in some factory presets. [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets Search this wiki page] for “Sonic Drive”.

[https://www.youtube.com/watch?v=hMDP4o9UJ-s Scott Henderson] • [https://www.youtube.com/watch?v=mb2IhvmrjYU SD9 Test/Demo] • [https://www.youtube.com/watch?v=xZOGX265Wj4 blondegraemey] • [https://www.youtube.com/watch?v=XVqPlG6g0cE Ariel Pozzo] • [https://www.youtube.com/watch?v=hXPJ2rcuYP8 PMTVUK] • [https://www.youtube.com/watch?v=KLoPTytBIWU SD9M Modification] • [https://www.youtube.com/watch?v=COLsf74-90w DutchGuitarDude] • [https://www.youtube.com/watch?v=M1bmi9Jg6BA Dani Rabin] • [https://www.youtube.com/watch?v=6CGzT46eBQo OZ NOY] • [https://www.youtube.com/watch?v=XTGmfsKHcXo945 History Of Guitar Distortion (JHS)] • [https://www.youtube.com/watch?v=EtT2gGU-6fU&t=843s 1970’s Op-Amp Distortion (JHS)] • [https://www.youtube.com/watch?v=qK02Ej5jZU8 Godlyke] • [https://www.youtube.com/watch?v=Md5JLW5K1l8 Michael Nielsen] • [https://www.youtube.com/watch?v=PDuccrFnlkw Leon Todd]

==SUHR RIOT GE (R) (Suhr Riot)==

[[file:x_Riot.jpg|150px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-ruckus-based-on-suhr-riot.123539/ Original forum thread]

[http://www.suhr.com/ John Suhr] started his company JS Technologies, after having worked with Bob Bradshaw and Fender. Suhr is known for his high-end guitars, amps, pedals, pickups etc. Read more about his amplifiers in the [http://wiki.fractalaudio.com/axefx2/index.php?title=Yeks_Guide_to_the_Fractal_Audio_Amp_Models Guide to the Fractal Audio Amp Models]. Suhr’s [https://www.suhr.com/electronics/pedals/distortion/suhr-riot/ Riot] pedal can turn a clean or slightly dirty amp into a high gain beast. It’s often praised for sounding like a real tube amp, so it falls in the “amp-in-a-box” category. A later version, “Riot Reloaded”, offers more gain, and there’s also a “mini” version. It's been said that MI Audio's Crunch Box was the inspiration for the Riot, and they do sound similar.

<blockquote>''“Riot is a versatile high-gain distortion pedal with the sonic characteristics and touch sensitivity of a high quality 100 watt tube amplifier.”'' [http://www.suhr.com/electronics/pedals/distortion/suhr-riot/ Suhr]</blockquote>

The pedal has these controls (more information in the manual): Distortion, Level, Tone (treble roll-off) and three-way voicing switch. With the switch to the left (red LED), the sound is natural and organic and it responds dynamically to your guitars volume control. In the middle position (blue LED + Silicon diode) it's high gain territory with a solid midrange and a tight bottom end. Switched to the right (Germanium diode, symmetrical), the pedal has a vintage high gain response with excellent definition.

Fractal Audio’s model is based on the original pedal. The names of the three models (originally named “Ruckus”) reflect the settings of the Voice switch. Start with the LED/Si (M) model, use a moderate Drive setting and turn up Level. The models are featured in some factory presets. [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets Search this wiki page] for “Riot”.

[https://www.youtube.com/watch?v=F5ebMq17Loo Riot into a Clean Amp] • [https://www.youtube.com/watch?v=D-XwOQ9oITw Riot into an Overdriven Amp] • [https://www.youtube.com/watch?v=fXSSE7SkDQg That Pedal Show] • [https://www.youtube.com/watch?v=y5YsCssU6bw Ian Thornley] • [https://www.youtube.com/watch?v=SCNA7Z6tPnc Pete Thorn] • [https://www.youtube.com/watch?v=Feyne-dQxjg Mark Day] • [https://www.youtube.com/watch?v=BcPB4LUXp4A John Cordy] • [https://www.youtube.com/watch?v=2TnTj1kvnyo Sasha Ivantic]

==SUHR RIOT LED (L) (Suhr Riot)==

See above, LED voicing (switch to the left).

==SUHR RIOT LED/SI (M) (Suhr Riot)==

See above, hybrid LED/Silicon Diode voicing (switch in the middle).

==SUNRISE SPLENDOR (JHS Pedals Morning Glory V4)==

[[file:morning_glory_v4.jpg|140px|left]]

The Morning Glory started as a modded Marshall Bluesbreaker and grew from there. It's a natural and crispy sounding low-to-medium overdrive. V4 was released in 2016.

Controls: Volume, Drive, Tone, Gain switch (boost), High Cut switch.

Separate models have the High Cut switch engaged or disengaged.

[https://www.youtube.com/watch?v=xIZ6hXSY2CQ JHS Pedal Morning Glory V4 (JHS)] • [https://www.youtube.com/watch?v=7ZS9SQBEotw The Story of the JHS Morning Glory (JHS)] • [https://www.youtube.com/watch?v=4EM_pqQ4DRE ProGuitarShop] • [https://www.youtube.com/watch?v=a6bDuYkuiIs Marshall Blues Breaker Style Overdrive Pedals (That Pedal Show)] • [https://www.youtube.com/watch?v=dUYJq_iiLh4 My Favorite JHS Pedals (JHS)] • [https://www.youtube.com/watch?v=tRENBTWsnSA Andrewmusikx] • [https://www.youtube.com/watch?v=-zko7JhYVbk Living Room GD]

==SUNRISE SPLENDOR HI-CUT==

See above. High Cut switch disengaged.

==SUPER FUZZ (Univox Super-Fuzz)==

From [https://en.wikipedia.org/wiki/Univox_Super-Fuzz Wikipedia]:

The original was designed in the late 1960s by the Japanese company Honey in the form of a (now extremely rare) multi effect called the Honey Psychedelic Machine. It was taken out and manufactured as a separate fuzz effect: Baby Crying Fuzz" FY-6. Honey was bought by Shin-Ei. The USA importer was Univox that marketed the pedal first as the Uni-Fuzz. Around 1970 the look changed to the version with the large rubber pad on the top and the name Super-Fuzz. The black/grey version around 1972 is the most sought-after version. The Super-Fuzz was also part of the Shin-Ei Fuzz Wah. ShinEi still makes the pedal today. The Super-Fuzz is used by many classic and modern bands and artists. The Behringer SF300 and Boss Hyper Fuzz are clones.

More history:
* [https://www.coda-effects.com/2018/07/univox-superfuzz-from-70s-history-post.html?m=0 Coda Effects]
* [https://www.vintageguitar.com/22533/univox-uni-fuzz-super-fuzz/ Vintage Guitar]
* [https://www.premierguitar.com/1969-univox-u-250-uni-fuzz Premier Guitar]
* [https://shin-ei.com/#fy6sf Shin-Ei]

It's an octave fuzz, using two germanium diodes to produce square wave clipping. Controls: Balance (volume), Expander (fuzz), two-position tone switch. The full-wave rectification of the circuit produces an upper octave as well as a slight lower octave. It can give the sound a lot of compression and a mild ring modulator effect.

The tone switch engages a 1 kHz filter that "scoops" the mids, giving a very fat, almost bassy tone, unique to this circuit. The Tone control in Fractal Audio's model varies the frequency of the notch.

Later versions of the original pedal feature an internal trim pot for controlling the octave balance. Use the Bias control in Fractal Audio's to simulate this.

[https://www.youtube.com/watch?v=zPwImCo9978 Reverb] • [https://www.youtube.com/watch?v=_6Mn2xpUnc4 Chris Jaxon] • [https://www.youtube.com/watch?v=0N6joOP573s demo] • [https://www.youtube.com/watch?v=Qces1CdLmD0 gearmanndude] • [https://www.youtube.com/watch?v=4DUiUObY5SQ gearmanndude] • [https://www.youtube.com/watch?v=gyXhLFGp5Fw JHS] • [https://www.youtube.com/watch?v=KLP4_s8DzjI Shin-Ei]

==SUPER OD (BOSS SD-1 Super OverDrive)==

[[file:x_SD1.jpg|140px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-super-od-based-on-boss-sd-1-super-overdrive.123595/ Original forum thread]

Dating back to 1981, this still is one of [https://www.boss.info/us/categories/stompboxes/ BOSS’] best-selling pedals. And rightfully so. It is the successor to the legendary '77 OD-1 (also yellow, also modeled by Fractal Audio). The SD-1 added a tone control. Contrary to the Tube Screamer, the SD-1 features asymmetrical clipping which is the type of clipping that occurs in tube amplifiers. The bottom and top of the waveform are clipped differently, favoring even-order harmonics. It's often said that because of this, the sweet sound of the SD-1 complements an amplifier, rather than changing it. The pedal doesn't provide that much gain, it isn't a distortion pedal. You can use it to drive a clean amp into blues territory, or to push an already distorted amp. With Drive turned down all the way and Level turned fully up, the SD-1 fattens the amp's own distortion and tightens the bass. It’s somewhat more aggressive than a Tube Screamer. And it does so admirably, as demonstrated by Zakk Wylde. He used it for a long time and his own signature overdrive pedal from MXR is based on it. Also contributing to its popularity is its amazing cheap price. You can buy one for $50 and create a tone that competes with boutique overdrives. There’s also a Waza Craft version: [https://www.boss.info/us/products/sd-1w/ SD-1W]. And in 2021 Boss released a 40th anniversary edition (SD-1 4a) with different cosmetics ([https://articles.boss.info/40-years-of-the-boss-sd-1-super-overdrive/ more info]).

<blockquote>''"The SD-1 Super OverDrive pedal produces the warm, natural distortion of an overdriven tube amplifier while maintaining the subtle nuances of a player's picking technique. This is one of BOSS' more subtle and smooth overdrive pedals, perfect for blues and rock."'' [https://www.boss.info/us/products/sd-1/ BOSS]</blockquote>

<blockquote>''"Unique asymmetric overdrive circuitry for a classic, natural tube amp growl.”''</blockquote>

<blockquote>''"The OD-1 didn’t have a tone control so the engineers felt that the tonal range was limited because of this. As an answer to the problem they came up with the SD-1. Comparing the two circuits reveals that they are very closely related and using the exact same overdrive circuit. When comparing the sound of the two pedals side by side, it is however obvious that they’re not identical. Opinions are divided when it comes to the question, which one sounds best, but there is no doubt that they’re both legendary overdrive pedals.”'' [http://bossarea.com/boss-sd-1-super-overdrive/ Bossarea]</blockquote>

[https://www.youtube.com/watch?v=f50qo96MqYI Comparison between the SD-1 and the MXR Wylde OD]

<blockquote>''"Early SD-1s used 1S1588 diodes. Later models used 1N916 and 1N4148. Our reference pedal has 1N916.”'' [https://forum.fractalaudio.com/threads/drive-a-b-comparison.160612/post-1923125 Fractal Audio]</blockquote>

[https://articles.boss.info/40-years-of-the-boss-sd-1-super-overdrive/ 40 Years of the BOSS SD-1 Super Overdrive] • [https://www.gitarrebass.de/workshops/true-bypass-fuer-den-boss-sd-1/ Gitarre & Bass (German)] • [https://www.tonehome.de/boss/sd-1-super-overdrive/ ToneHome] • [https://www.guitarworld.com/features/boss-sd-1-super-overdrive-pedal The drive pedal of choice for Zakk Wylde and Josh Homme]

The SD-1 has these controls: Drive, Tone and Level. Josh Homme (Queens of the Stone Age) uses the SD-1 in a particular way: he turns up Tone all the way, and Drive all the way down, effectively turning it into a kind of treble booster. Zakk Wilde sets everything at one o'clock.

The model is featured in some factory presets. [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets Search this wiki page] for “Super OD”. The Super OD model is also available as an input boost type in the Amp block.

[https://www.youtube.com/watch?v=ddLMb51NjtQ Leon Todd: Zakk Wylde's SD-1 Settings] • [https://www.youtube.com/watch?v=jhUGew-bLIA BOSSchannel 1] • [https://www.youtube.com/watch?v=HUHMNV7bJxI BOSSchannel 2] • [https://www.youtube.com/watch?time_continue=1&v=SaLh_IfBbbw SD-1W BOSSchannel 3 ] • [https://www.youtube.com/watch?v=tSCkcsyh-MY BOSSchannel 4] • [https://www.youtube.com/watch?v=XpvyfdOJMpk ProGuitarShop] • [https://www.youtube.com/watch?v=ICU1X4EQ3pQ Leon Todd: 10 Drive Pedals Compared] • [https://www.youtube.com/watch?v=f50qo96MqYI Leon Todd: Boss SD-1 vs Wylde OD] • [https://www.youtube.com/watch?v=QiiPVe_7MsM Sweetwater] • [https://www.youtube.com/watch?v=odwDfQllyYU Japan vs Taiwan] • [https://www.youtube.com/watch?v=-LieE9JKqxo BK Butler Tube Driver vs TS9 vs SD1] • [https://www.youtube.com/watch?t=629&v=Zg6JYTbt0d4 Boss Is Best (JHS)] • [https://www.youtube.com/watch?v=GxvwyCb5mP0&t=133s Must Have Guitar Rig Essentials (JHS)] • [https://www.youtube.com/watch?v=IoHPzg0ufnk intheblues] • [https://www.youtube.com/watch?v=FdAQnjpZCSA Studio Rats: SD-1 versus TS] • [https://www.youtube.com/watch?v=IyUTs8kzA7M PMTVUK 1] • [https://www.youtube.com/watch?v=puzS1A3DweA PMTVUK 2]

==T808 OD (Ibanez TS-808 Tube Screamer)==

[[file:x_TS.jpg|160px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-t808-od-and-t808-mod-based-on-ibanez-ts9-tube-screamer.123623/ Original forum thread]

The holy grail of overdrive pedals and a key component of Stevie Ray Vaughan’s signature sound. One of his Tube Screamers listed for $11.000 in 2016. Other users include John Mayer, Eric Johnson, The Edge, Gary Moore, David Gilmour, Trey Anastasio, Adam Levine, Brent Mason, and probably half of all players out there. The first popular version was the (now very rare) ’79 Overdrive Pro TS-808. Also referred to as “narrow box” because of its small switch. In 2014 Ibanez made the TS-80835TH reissue to celebrate 35 years of Tube Screamers. The “narrow box“ was followed in ’80 by the larger Overdrive Pro TS808 (without hyphen). It carried the legendary JRC 4558D chip and other improvements. This one is considered to sound the best, and people are willing to pay the price for it. The ’82 TS9, better looking with a larger footswitch, a differently named 4558 chip and a couple of different resistors but otherwise the same circuit, sounds very similar to the TS808, with a bit more presence. It can be modified to sound exactly like an 808. The 808 and TS9 are the most coveted originals but many versions, reissues and anniversary editions followed. Originally vintage Tube Screamers were made for [http://www.ibanez.com/ Ibanez] by Nisshin/Maxon. The collaboration ended in 2002. [https://maxonfx.com/ Maxon] now carry their own line; see the section about the Maxoff model.

<blockquote>''"The Ibanez Tube Screamer is a guitar overdrive pedal, made by Ibanez. The pedal has a characteristic mid-boosted tone popular with blues players. The "legendary" Tube Screamer has been used by guitarists such as Stevie Ray Vaughan to create their signature sound, and is one of the most popular and most copied overdrive pedal."'' [https://en.wikipedia.org/wiki/Ibanez_Tube_Screamer Wikipedia]</blockquote>

[[file:ts book.jpg|450px|right]]

The Tube Screamer’s unique feature is its mid-hump: it emphasizes the middle frequencies which makes it a favorite of many blues players. They often play through Fender amps and many of these are slightly scooped in the middle frequencies area. The pedal helps cutting through the mix. Another feature of the Tube Screamer is that some of the original clean signal is mixed in at its clipping stage, which improves dynamics and clarity. Tube Screamers are also used by rock players to tighten the amp's distortion, because the pedal cuts bass into the amplifier. Even Stevie Ray Vaughan used a Tube Screamer (or two in series) to boost his already overdriven amps, with Drive set low and Level set high. Another approach with high gain amps is to crank Drive and Level and turn down Tone all the way, which is [https://www.youtube.com/watch?v=Wlfs4NyfLms what Mark Tremonti does]. Pedal builders like Analog Man and Robert Keeley offer modding services for Tube Screamers, increasing gain and bass. Many manufacturers also design pedals based on the Tube Screamer. [https://www.jhspedals.info/bonsai JHS Pedals’ Bonsai pedal] provides many different Tube Screamer flavors in a single pedal. The Tube Screamer uses symmetrical clipping, as opposed to asymmetrical clipping used in the BOSS OD-1, the competitor at the time (released one year before the Tube Screamer), and its successor the BOSS SD-1. It’s said that the choice for symmetrical clipping was made because of the already existing patent of BOSS on solid-state asymmetrical clipping.

<blockquote>''“If you look at the schematic between a Tube Screamer and a Boss OD-1, they’re almost exactly the same thing,” Lomas says. “The OD-1, though, is what they call an asymmetrical clipper. When you put a signal in it, it does not distort the top and bottom of the soundwave the same. Instead, it distorts one differently—the way a tube would. The original Boss OverDrive was designed to be a tube simulator, which was really big back then because, of course, most amplifiers were starting to get away from tubes. They were solid-state, and they really sounded like shit. So, there was a market for tube-simulation pedals. I believe that’s probably why the Tube Screamer was named the Tube Screamer. The TS808 also differed from the OD-1 in that it had a Tone control, featured a common JRC 4558D integrated circuit (IC) chip, and had a small rectangular footswitch. “The Tube Screamer was really the first pedal I saw that had an IC in it,” says Lomas. “All the overdrives prior to the Tube Screamer were built around transistors.” Lomas contends that the sweet, vocal midrange sound the TS808 is known for has everything to do with that JRC4558D IC chip—which explains why Lomas and many other overdrive aficionados prefer the sound of the original over other permutations of the pedal.”'' [https://www.premierguitar.com/articles/11528-green-giant-history-of-the-tube-screamer Premier Guitar]</blockquote>

Timeline:
* 1979-1982: TS-808, JRC4558D, Japan
* 1982-1985: TS-9, JRC4558D, NJM4558, JRC2043DD, TA75558, Japan
* 1984: ST9 Nine Series Super Tube Screamer, 2x JRC4558D
* 1985: STL (Super Tube Series), 2x JRC4558D, Japan
* 1986-1989: TS-10, JRC4558, MC4558, Japan and Taiwan
* 1989-1999: TS-5 Soundtank, TA75558, NJM4558, Taiwan
* 1993: TS9 Nine Series Reissue, TA75558, Japan
* 1996: TS-9 Reissue, TA75558 CE, Japan
* 1998: TS9DX Nine Series, TA75558
* 2000: TS-7 Tone-Lok, NJM4558, JRC4558D, Taiwan and China
* 2002: TS-9 Reissue (not Maxon anymore)
* 2004: TS-808 Reissue, JRC5458, JRC4588D, Japan
* 2008: TS 808HW, JRC4558, Japan
* 2010: TS9B Bass Tube Screamer
* 2012: TS-9 30th Anniversary, JRC4558
* 2014: TS808DX
* 2014: Ibanez TS-808 35TH (narrow box reissue), JRC4558
* 2015: Ibanez Tube Screamer Mini
* And more …

[http://www.analogman.com/tshist.htm Analog Man] • [http://www.geofex.com/article_folders/tstech/tsxtech.htm Geofex] • [https://www.premierguitar.com/articles/11528-green-giant-history-of-the-tube-screamer Premier Guitar's History of the Tube Screamer] • [http://www.electrosmash.com/tube-screamer-analysis ElectroSmash] • [https://www.gitarrebass.de/equipment/die-tube-screamer-story/ Gitarre & Bass: Ibanez Tube Screamer Story (German)] •
[https://www.gitarrebass.de/heftarchiv/2009-01/ibanez-tube-screamer-ts808hw-overdrive-pedal/ Gitarre & Bass: Ibanez Tube Screamer TS808HW (German)] • [https://www.gitarrebass.de/equipment/ibanez-ts-808-35th-im-test/ Gitarre & Bass: Ibanez TS-808 35TH (German)]

The pedal has just three control: Drive, Tone (doesn’t affect the mid-hump) and Level.

Like the pedal, Fractal Audio’s models of the Tube Screamer are popular. The T808 models were originally based on a TS9DX but the current models are based on the TS-808.
The T808 MOD model incorporates virtual mods for broader frequency range, more gain and more output level.
The T808 models are also available as input boosts in the Amp block.
The TS9DX + and TS9DX Hot models are based on two modes of the ’98 TS9-DX Turbo Tube Screamer with the original TA75558 chip plus four separate circuits through a Mode switch. The “Hot” model replaces the diodes with LEDs and has less gain than the + mode. The “+” mode(l) provides more gain and is darker. The Valve Screamer VS9 model is based on a TS9.

<blockquote>''"The TS-808 used 1S1588 diodes. The TS-9 used 1N914 (equivalent to 1N4148). The Axe-Fx III model is a TS-808 so it defaults to 1S1588. Our reference pedal is a TS-808.”'' [https://forum.fractalaudio.com/threads/drive-a-b-comparison.160612/post-1923125 Fractal Audio]</blockquote>

[https://www.youtube.com/watch?v=QWersvdWndM Tyler Grund] • [https://www.youtube.com/watch?v=yDgQUHNvBKA shnobel: TS9 vs TS 808] • [https://www.youtube.com/watch?v=fXSSE7SkDQg That Pedal Show: 5 Modern Classic OD Pedals] • [https://www.youtube.com/watch?v=l7OSahzgd0M That Pedal Show: Super Overdrive Or Tube Screamer?] • [https://www.youtube.com/watch?v=g5m7Dpw0G1g Philip McKnight] • [https://www.youtube.com/watch?v=-LieE9JKqxo shnobel: TS9 vs SD-1] • [https://www.youtube.com/watch?v=-LieE9JKqxo Tube Driver vs TS9 vs SD1]] • [https://www.youtube.com/watch?v=zoLFctLiwuE Ibanez] • [https://www.youtube.com/watch?v=kDEetp4snpM Reverb] • [https://www.youtube.com/watch?v=QP6GUQRzWjU ProGuitarShop] • [https://www.youtube.com/watch?v=7WtsheEEspk gearmanndude: Ibanez TS9] • [https://www.youtube.com/watch?v=NEWcilhBcSE gearmanndude: JHS Bonsai] • [https://www.youtube.com/watch?v=ixtI-KUMJWA Vintage vs. New Tubescreamers (Wampler)] • [https://www.youtube.com/watch?v=lwEIsbA-5bU Stacking Tube Screamers (Wampler)] • [https://www.youtube.com/watch?v=y7ozkgpIryw&t=198s Do all tubescreamers sound the same? (Wampler)] • [https://www.youtube.com/watch?v=3c5Ar-iaWRE Busting the myth about TS9 and TS808 circuits (Wampler)] • [https://www.youtube.com/watch?v=TEAkxW1ZvCk Boss SD-1 vs Ibanez TS808 vs DOD 250] • [https://www.youtube.com/watch?v=z2YkRazrxcU Boss OD-1 & SD-1 vs Ibanez TS808 & TS9] • [https://www.youtube.com/watch?v=otkW_q0_VIU&t=553s Diode-Based Overdrive and Distortion Effects] • [https://www.youtube.com/watch?v=pFOD6s0IRoM Bad Monkey vs Tube Screamer (JHS)] • [https://www.youtube.com/watch?v=H3Yrr22cEFE This Is Why I Think Tube Screamers Suck]

==T808 MOD (modded Ibanez TS-808 Tube Screamer)==

See above.

==TAPE DISTORTION (tape distortion)==

[[file:TDST.png|200px]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-tape-dist.123694/ Original forum thread]

This model adds the tone print and distortion of an analog reel-to-reel recorder. It doesn't add much distortion, but it compresses the sound and makes it fat and chewy. Ritchie Blackmore is known for sending his sound through a tape recorder in his old days, after ditching his treble boosters.

[http://www.soundonsound.com/techniques/analogue-warmth Sound On Sound: Analogue Warmth] • [http://ledgernote.com/columns/mixing-mastering/what-is-tape-saturation-best-plugins/ Ledger Note: What Is Tape Saturation?] • [http://www.woodytone.com/2009/04/20/ritchie-blackmores-tone-and-more-part-1/ WoodyTone: Ritchie Blackmore’s Tone]

Put the Tape Distortion model behind the Cab block for best results and use the Drive parameter to set the amount of virtual tape distortion. The “Tape Driver” or “Tape Drive” factory preset demonstrates this. Be aware that it will sum a stereo signal to mono, including a stereo Cab block. To prevent that, move it to right behind the Amp block. Alternatively, use the Preamp simulation in the Cabinet block. It provides similar tape and channel strip simulations, like “vintage” and “tube”, without requiring a block on the grid.

The model can also be used to add an extra virtual tube gain stage to an amp. Select the HV tube, keep Drive low and set Level as appropriate.

<blockquote>''"It's just a generic tape distortion simulator. I used an old Ampex EQ curve basically."'' Fractal Audio</blockquote>

<blockquote>''"The tape drive is meant to be used anywhere in the chain. I've been using it after the amp to fatten things up and it works well for that. Be careful though, the drive block is mono so you can get phase issues if you put it after a stereo effect."'' Fractal Audio</blockquote>

==TIMOTHY DOWN (Paul Cochrane Timmy V4)==

[[file:x_Timmy.jpg|120px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-timothy-based-on-paul-cochranes-timmy.123751/ Original forum thread]

First there was the Tim, a pedal like the Timmy, but in a larger enclosure with a boost and effects loop. Its name was based on Tim The Enchanter (reportedly), the wizard in Monty Python’s Holy Grail movie. Timmy is Tim’s little brother, who has outlived its older sibling. Both are hand-made pedals which originally couldn’t be bought from any shop. They had to be ordered from the designer Paul Cochrane personally. Rave reviews on The Gear Page and other internet forums contributed to long waitlists. Boutique, but not expensive. These days [https://www.jimdunlop.com/mxr-timmy-overdrive/ MXR] builds the pedal ($130). The Timmy is considered by some to be the best overdrive pedal in the world, because of its extremely transparent, organic character and responsive crunch. It goes along fine with single coils as well as humbuckers, and stacks well with other overdrives. It can also operate as a clean boost, with the controls turned down.

<blockquote>''“The MXR Timmy Overdrive provides a huge range of gritty, textured tones that enhance your rig’s sound while preserving its fundamental voice—and in an MXR mini housing, it’ll free up serious pedalboard space. The pedal’s based on a design from veteran pedal builder Paul Cochrane that’s widely celebrated among high level pros, from first-call Nashville player Kenny Greenberg to first-call L.A. player Lyle Workman to rockstar Brad Whitford. Thanks to Paul’s inventive implementation of clipping options and tone controls, the Timmy Overdrive is a dream come true for working guitar players. The Clip switch provides three different clipping styles for a multitude of scenarios, whether you need a big, bold always-on sound with a ton of headroom to slam the front end of your amp, a more compressed and saturated sound for fat chords, or anything in between. The Bass and Treble controls offer further refinement in two key ways. First, they’re cut-only, keeping your signal’s character intact while making it super easy to dial in a clean boost. Second, Paul wired the Bass control to affect your pre-OD signal so that you can your maintain low end at lower Gain settings and the Treble control to affect your post-OD signal so that you can adjust the top end to keep dirty settings smooth and musical. Finally, the MXR design team worked with Paul to select an op-amp that perfectly complements his expertly crafted design. They chose the LF353, a component well-respected by Dunlop engineers for providing high output, high gain, and hi-fi signal delivery. The resulting MXR Timmy Overdrive is a professional-grade must-have for players who want sweet, harmonic breakup that responds to playing dynamics and maintains a rig’s personality at a fraction of the standard pedal size.”'' [https://www.jimdunlop.com/mxr-timmy-overdrive/ MXR]</blockquote>

There has been some controversy around pedals from other manufacturers, accused of being exact copies/clones of the Timmy circuit, Danelectro’s Cool Cat Transparent Overdrive V1 being one of them. This [https://www.youtube.com/watch?v=5Oukng0DxUY That Pedal Show episode] demonstrates the similarities between the Timmy, Jan Ray and Amp Eleven.

[https://www.youtube.com/watch?v=5Oukng0DxUY A Closer Look] • [https://www.guitarworld.com/features/classic-gear-paul-cochrane-timmy Guitar World] • [https://www.guitarworld.com/reviews/mxr-timmy-overdrive-review Guitar World] • [https://www.musicradar.com/reviews/mxr-timmy Music Radar]

The pedal’s controls are Bass (cuts bass as it goes clockwise), Gain, Volume and Treble (cuts treble as it goes clockwise). A toggle switch changes the diode configuration. Represented by the three models of this pedal. The Bass controls cuts bass, start here to sculpt the sound. The Bass control is pre-gain, while the Treble control is post-gain.

<blockquote>''“I have a blue one.”'' [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-version-3-02-public-beta.147926/post-1749769 Fractal Audio]</blockquote>

<blockquote>''“The tone controls are now faithful to the actual pedal and decrease bass/treble when turned clockwise."'' (firmware 13.x for the Axe-Fx III)</blockquote>

Fractal Audio provides three diode-based models of the pedal with the 3-way switch. The Up model features asymmetrical clipping, which seems to be the preferred mode among users. The Med model has the least compressed symmetrical clipping. The Down model delivers compressed symmetrical clipping. With asymmetric clipping, the bottom and top of the waveform are clipped differently, favoring even-order harmonics. Symmetrical clipping can sound more dissonant.

In current firmware, the models are based on the pedal's V4 version.

<blockquote>''“Our new reference Timmy pedal matches the "V4" schematic."'' [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-26-01-release.206910/page-3#post-2581250 Fractal Audio]</blockquote>

[https://www.youtube.com/watch?v=aZJZK6rzjns Tim The Enchanter from Monty Python's The Holy Grail] • [https://www.youtube.com/watch?v=AViMnHAV-lw Gearmanndude] • [https://www.youtube.com/watch?v=4Guqunfe_m4 Timmy versus Timmy] • [https://www.youtube.com/watch?v=OZdUhd-nOrc Brett Kingman] • [https://www.youtube.com/watch?v=Xs2aV-cGHcI Livingroom Gear Demos] • [https://www.youtube.com/watch?v=HhcY3vEDSj4 Bluesman] • [https://www.youtube.com/watch?v=ByqJ6F-22vk That Pedal Show: Dream Overdrives: Timmy, Jan Ray & Amp11] • [https://www.youtube.com/watch?v=ByqJ6F-22vk intheblues] • [https://www.youtube.com/watch?v=TtmntmKU9Zs How Good is the Timmy Overdrive Pedal?] • [https://www.youtube.com/watch?v=pSTkpiaIl-Q Reverb Tone Report] • [https://www.youtube.com/watch?v=GXixalSxD20 Riffs, Beards & Gear] • [https://www.youtube.com/watch?v=Fdw8V9Vgbho Jan Ray versus Timmy] • [https://www.youtube.com/watch?v=wayzzbgcW10 Leon Todd]

==TIMOTHY MID (Paul Cochrane Timmy V4)==

See above, switch in middle position (symmetrical clipping).

==TIMOTHY UP (Paul Cochrane Timmy V4)==

See above, switch in top position (asymmetrical clipping).

==TONE OF KINGS (Analog Man King of Tone)==

[[file:x_KoT.jpg|275px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-tone-of-kings-based-on-king-of-tone-aka-kot.148207/ Original forum thread]

Together with pedals such as the Klon, the King of Tone (aka KoT), made by [http://www.analogman.com/kingtone.htm Analog Man] (Mike Piera), is a pedal in high demand, even at its current price of $265 (at the time of writing) for a new one. Used ones sell for over $400. After ordering, it will take years to be shipped. [http://www.analogman.com/kingtone.htm#players List of KoT players.] Like a couple of other pedals / models covered on this page, the KoT is a very transparent overdrive that preserves the tone of the guitar. Not too dry, not too saturated. It aimes at natural amp-like sounding overdrive. It can handle any kind of amp. It’s originally based around the Marshall Bluesbreaker Mk II pedal (also modeled by Fractal Audio), rather than the ubiquitous Tube Screamer circuit. There have been several versions. V4, the current one, has been unaltered since 2005.

<blockquote>''“We totally redid the circuit with different diodes, chips, capacitors, treble boost, modes- pretty much everything was changed. And of course the KOT is two pedal circuits in one box. So our KOT pedal is not much like, and does not sound much like a BB pedal anymore. Especially the clean or distortion modes are different, and the higher gain option changes it even more, making it more useful throughout the DRIVE knob range. We used the higher gain KOT circuit as the base for the Prince Of Tone which came out in 2012, and improved the DISTORTION mode also on the POT.''</blockquote>
<blockquote>''The King Of Tone overdrive was designed to take an amp at reasonable settings, and make it sound like it would sound if it were naturally driven to pure, smooth, tube distortion. It was fine tuned with Jim's (Jim Weider) 1960s Fender Deluxe Reverb amp to duplicate the sound when his amp is singing, but at lower volume settings - to simulate the natural tube amp distortion of preamp and power tubes. It does the same thing on other amps like Vox, Marshall, etc, making them sing in their own voice. Jim's amp was modified by our good friend the late Cesar Diaz, and is about the best sounding Fender amp I have heard. Later on, I tested the KoT on my own 1966 Deluxe Reverb amp. My amp is stock, and does not sound that great when it's cranked up. It gets loud but not very warm or singing, a little harsh. My amp sounds MUCH better using the KoT for overdrive, then it sounds very close to Jim's amp.''</blockquote>
<blockquote>''The KoT is one of the few overdrive pedals available that is NOT based on a Tube Screamer circuit. In OD mode, it has a little less drive available than a Tube Screamer. It has quite a bit more volume available than a Tube Screamer and The TONE control has a similar range. The KoT has less compression than a tube screamer, and also does not boost the mids or cut the low end as much. It does not have a large amount of distortion.''</blockquote>
<blockquote>''Once we had a prototype that Jim liked and used on stage several times, I emailed the circuit to my collaborator in Japan, Ohbayashi san, and he tried several ideas I gave him. CAMTAC Ohbayashi san has a suberb ear for details like capacitor and chip selection and came up with some great ideas for the pedal- a chip and diodes that made it sound even better! The special JRC chip he preferred was designed for audio tone controls, and has a warm yet clear sound. The diodes are more open sounding, for a stronger, clearer, less compressed sound and more volume. All the nuances of your playing and each string of the guitar will come through clearly.''</blockquote>
<blockquote>''The Version 4 King of Tone was developed in late 2005 due to popular demand for separate controls for each channel of the original 4 knob KoT. The original KoT was one overdrive circuit, with 2 channels, having separate volume controls and internal configurations. Almost all "dual overdrive" pedals available are like this. The Ver4 KoT is actually TWO overdrive pedals in one box, one on each side. Remember that each side is a separate pedal, and they are the same except for how you set the DIP switches. Each side has an on/off switch, LED, and three independant knobs. Each side also has configuration DIP switches and a TREBLE trim pot on the inside. Having two actual overdrive circuits allows you to use both pedals at once, in series (stacking) for even more possible tones and levels of drive!''</blockquote>
<blockquote>''Each side has it's own Volume, Drive, and Tone control and LED. We use SUPER BRIGHT Yellow and Red LEDs so you can easily tell which channel is selected. In addition, there is a TREBLE BOOST knob on the inside of the pedal. This is a small knob or trimpot which can be turned by hand or with a pick or small screwdriver. Jim does not need more treble for his Tele, but I found it allowed some superb tones with my '59 reissue Les Paul through my '69 Marshall amp, similar to the sweet yet biting tones of Michael Bloomfield (I believe he used a Fender Twin amp with his famous 1959 sunburst).''</blockquote>
<blockquote>''There is also a four position configuration DIP switch on the inside of the KoT which you can use to choose between Clean, OD, and DISTORTION modes for each side. The modes are:''</blockquote>
<blockquote>''1) Normal Overdrive mode (OD mode) : This is the standard King Of Tone sound, which Jim likes best- a little less drive available than a tube screamer. Factory DIP switch setting has this mode on the right (red) channel. This mode can get about 4 times louder than a tube screamer if desired. This mode engages SOFT CLIPPING like most overdrive pedals.''</blockquote>
<blockquote>''2) CLEAN mode : This mode has less drive, can be used for clean boosts or clearer, louder sounds. It's like a clean boost with an overdrive knob. CLEAN MODE is even less compressed than the standard OD mode. The factory DIP switch setting uses this mode on the left (yellow) channel. This mode can get twice as loud as the OD mode. You can think of the clean mode as the OD mode with the overdrive removed, allowing louder, clearer tone. But the drive knob still functions and can add some drive to the sound, and volume as it's turned up. It's a cool sound with the drive knob cranked! This mode has NO CLIPPING, like most boost pedals.''</blockquote>
<blockquote>''3) DISTORTION mode : This mode has more drive than the standard OD mode- a touch of hard distortion. The sound is more compressed, yet retains the King Of Tone character. This mode can get about twice as loud as a tube screamer. Think of this mode as a cross between a Boss DS-1 distortion and OD-1 overdrive, with more clarity. We recommend most players use the OD and CLEAN modes. While the DIST mode sounds great, and I like to use it on certain occasions, it does not allow the pedal to get its absolute BEST tones. You can put an aged single malt Scotch whisky on ice, but it would be a shame to dilute it! The DIST mode is awesome with the HIGHER GAIN option. This mode engages HARD CLIPPING like most distortion pedals and some fuzzes. It's best to turn the OD dip switch down when using the DIST mode, especially with the higher gain option to avoid duplicate clipping (soft and hard clipping together).''</blockquote>
''<blockquote>Either side can be set to any of the three modes, with the DIP switches. I recommend setting the right side for most distorted sounds and the left for cleaner, then when used together you get more of a volume boost. But if you want more distortion and compression, you can try it the other way around too.''</blockquote>
<blockquote>''At low DRIVE settings, or when playing softly, there is not much difference between the three modes- they all clean up very nicely as the clipping does not start until you turn the DRIVE knob up higher. This pedal cleans up a lot better than a Tube Screamer type pedal, if you play softly or turn your guitar down they will not have the underlying fuzziness that most pedals have.”'' [http://www.analogman.com/kingtone.htm Analog Man]</blockquote>

[https://reverb.com/news/why-is-the-analogman-king-of-tone-in-such-high-demand Reverb.com] • [https://www.gitarrebass.de/workshops/effektiv-analog-man-king-of-tone/ Gitarre & Bass (German)] • [https://www.youtube.com/watch?v=7fvyWnH-PSY Analog Man’s BEST Pedals (JHS)]

The pedal’s controls are Drive, Volume and Tone.

The diode-based King of Tone model is a digital model of Analog Man’s pedal. The pedal has two circuits, and each can be switched between boost, overdrive and distotion. Fractal Audio has modeled the pedal in the overdrive mode, which provides a mild overdrive. The distortion mode doesn’t have the same appeal as the OD mode, and the pedal’s clean boost is already covered by other models.

[https://forum.fractalaudio.com/threads/tone-of-kings-model-does-not-sound-like-the-real-pedal.175442/post-2128354 How to produce the clean boosted sound and distorted sounds of the pedal]

[https://www.youtube.com/watch?v=rkzYWV8HJTw Jim Weider] • [https://www.youtube.com/watch?v=0VqCKYlEENI That Pedal Show: King Of Tone Alternatives] • [https://www.youtube.com/watch?v=h9nVYAwATBo That Pedal Show: Can Two Prince Of Tone Overdrives Sound Like One King Of Tone?] • [https://www.youtube.com/watch?v=c0VMOnCd0LI NickSterlingRocks] • [https://www.youtube.com/watch?v=vRhYvKFZmIo SuperFunAwesomeHappyTime Pedal Show] • [https://www.youtube.com/watch?v=2VxJaNiHz30 Carson Lee] • [https://www.youtube.com/watch?v=QgrBbph_8Kw Reverb.com] • [https://www.youtube.com/watch?v=FiUCpB4R38g King of Tone vs Klon Centaur] • [https://www.youtube.com/watch?v=nsQJt0EzIXQ Audiofanzine] • [https://www.youtube.com/watch?v=O7tYWQ4C8r4 Intheblues] • [https://www.youtube.com/watch?v=s54Vrx9rTHY&t=336s What Is A Blues Breaker? (JHS)] • [https://www.youtube.com/watch?v=7fvyWnH-PSY&t=86s Analog Man’s BEST Pedals (JHS)] • [https://www.youtube.com/watch?v=taEW55vVmk4 John Wesley] • [https://www.youtube.com/watch?v=t1VWYfOJ0Lo&t=1663s Kenny Wayne Shepherd Rig Rundown] • [https://www.youtube.com/watch?v=jR-3-5ospWw Daniel TheGigRig] • [https://www.youtube.com/watch?v=wNO6CtLtC-A gearmanndude: High Gain Red side] • [https://www.youtube.com/watch?v=pI7VKQHuZjs gearmanndude] • [https://www.youtube.com/watch?v=Hhk4f06neVU Mark Pappas] • [https://www.youtube.com/watch?v=YCSkbdoiWgo Marty Music] • [https://www.youtube.com/watch?v=h3wBxfmTkeI Friday Fretworks] • [https://www.youtube.com/watch?v=C6rrsNVvtXE Paul Davids]

==TREBLE BOOST (silicon treble booster circuit)==

[[file:x_Treble.jpg|280px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-treb-boost-based-on-dallas-rangemaster.123723/ Original forum thread]

This model is based on a classic treble booster circuit. This was designed as an accessory for amplifiers to roll off lows and boost the higher frequencies, like the Top Boost add-on for early Vox amps, sitting on top of the amplifier. Guitar players soon discovered it was also great for something else: pushing an edge-of-breakup or overdriven amp into “more”. Emphasis on certain frequencies makes the treble boost a non-clean boost but, unlike a fuzz, it stays close to the amp's raw tone. It also creates awesome clean tones when turning down the guitar volume. So, the label “treble booster” doesn’t really do justice to this pedal’s possibilities. While the ’65 Dallas Rangemaster may be the most famous one, other brands were also popular, like the Hornby-Skewes Treble Booster, and Orange Treble&Bass Booster. The circuit is very simple, and many clones of classic treble boosters exist. But because they are rare, people pay thousands of dollars for an original. A popular clone of the Dallas Rangemaster is made by Analog Man: [http://www.analogman.com/beano.htm Beano Boost]. [http://www.treblebooster.net/ BSM] builds all kinds of treble boosters these days. [https://shop.brianmayguitars.co.uk/bmg-electronics/bmg-tb-classic.html Brian May sells his own one], made by [https://deacyamp.com/ Knight Audio Technologies (KAT)].

Famous treble boost users include Rory Gallagher, Jimmy Page, Jeff Beck, Eric Clapton, Ritchie Blackmore (in Deep Purple’s “Child in time” and “Smoke on the water”), [https://www.youtube.com/watch?v=eQFdP6PaKTk&t=169s Brian May], Tony Iommi (in Black Sabbath's “Paranoid”), Mark Bolan, Wishbone Ash and Billy Gibbons.

<blockquote>''“The Dallas Rangemaster Treble Booster was an effects unit made for guitarists in the 1960s. Its function was two-fold: to increase the signal strength of the guitar going into the amplifier, and to increase tones at the high end of the spectrum (a treble booster). The need for a treble booster arose in the mid-1960s as British amplifiers such as the Vox AC30 or Marshall JTM45, tended to produce a slightly dark, muddy sound when overdriven, particularly when used with humbucking pickups. A pre-amplifier that also boosted treble proved a solution. The Dallas Rangemaster Treble Booster was first made in the 1960's by Dallas Musical Ltd., incorporated in 1959. It made guitars and amplifiers under different brand names, including Dallas, Shaftesbury, and Rangemaster. The unit is simple, and consists of a grey metal box with an on/off switch, a potentiometer for the booster setting, and an in- and output. It is made to stand on top of an amplifier rather than on the floor. Its circuitry is simple, and contains (besides the potentiometer--usually 10K, sometimes 20K--and the on/off switch) only a germanium transistor, four capacitors, three resistors, and a battery. The transistor was a Mullard or unbranded OC44 or Mullard OC71. By the 1980s Treble Boosters had gone out of fashion. How many Rangemaster Treble Boosters were built is unknown. Due to limited supply on the second hand market they are collectible, even if the going rate is only a fraction of what it used to be in the mid-2000s. In Premier Guitar, Kenny Rardin describes his quest for one of the effects, which started with puzzlement over how Eric Clapton and Ritchie Blackmore achieved their tone; he spent years looking for a Rangemaster. Rumours of Eric Clapton having used a Rangemaster Treble Booster during his stint with John Mayall's Blues Breakers have never been confirmed. Photos of the recording sessions of the "Blues Breakers With Eric Clapton" exist, but a Rangemaster Treble Booster is not visible in any of them. It is assumed the rumours started in the late 90's when clones of the Rangemaster Treble Booster.”'' [https://en.wikipedia.org/wiki/Dallas_Rangemaster_Treble_Booster Wikipedia]</blockquote>

[https://reverb.com/news/when-did-guitarists-first-use-fuzz-wah-and-other-transistor-based-effects Reverb.com] • [http://www.gitarrebass.de/equipment/treble-booster-im-test/ Gitarre & Bass] • [https://www.vintageguitar.com/20424/the-dallas-rangemaster/ Vintage Guitar] • [http://www.premierguitar.com/articles/the-rangemaster-1 Premier Guitar: The Rangemaster] • [https://www.electrosmash.com/dallas-rangemaster Electrosmash] • [http://guitaraholicsu.com/what-does-clapton-black-sabbath-and-queen-have-in-common/ Guitaraholicsu] • [http://www.geofex.com/article_folders/rangemaster/atboost.pdf GEO Fex] • [https://www.youtube.com/watch?v=7fvyWnH-PSY&t=517s Analog Man’s BEST Pedals (JHS)]

The Dallas Rangemaster’s only knob was “Set”, which adjusts the amount of boost.

<blockquote>''"Boost was a switch and engaged the effect. Set was the amount of boost and is equivalent to Drive."'' [https://forum.fractalaudio.com/threads/question-about-treble-boost.102850/post-1232043 Fractal Audio]</blockquote>

To get the most out of a treble booster, use it as intended: select the Normal (dark) channel of a turned-up Vox or Plexi, and turn down the guitar volume. Don’t run it into a clean amp.

Fractal Audio’s Treble Boost model is modeled after a silicon treble booster. It has not been disclosed which actual circuit it is based on. The Rangemaster used germanium transistors, while Hornby-Skewes built silicon-based boosters. The Eternal Love drive model can also operate as a treble booster. Fractal Audio provides a separate Mid Boost model. The use of a treble booster is featured in some factory presets. [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets Search this wiki page] for “treble”. The Treble Booster is also available as an input boost type in the Amp block.

[https://www.youtube.com/watch?v=lQ2OnBIEDFM With a Vox AC30 ‘63 JMI] • [https://www.youtube.com/watch?v=iBjXiNVTWZI&t=382s The First Guitar Effects Ever (JHS)] • [https://www.youtube.com/watch?v=0wmWfBRmpLA TheToneShack] • [https://www.youtube.com/watch?v=VFrgw49MrBw British Pedal Company] • [https://www.youtube.com/watch?v=oNV0wpErolQ Rory Gallagher] • [https://www.youtube.com/watch?v=qUBAkwdoewA That Pedal Show: Tremendous Treble Boosters for Glorious Classic Drive Tones] • [https://www.youtube.com/watch?v=eQFdP6PaKTk Pete Thorn: The Most Underrated Guitar effect] • [https://www.youtube.com/watch?v=YAP7A6k1nq8 Pete Thorn: Everyone Needs a Treble Booster] • [https://www.youtube.com/watch?v=sj9iMH0AY20 Brett Kingman: Fryer Treble Boosters]

==TS9DX + (Ibanez TS9DX Turbo Tube Screamer)==

[[file:ts9dx.jpg|150px]]

See T808.

==TS9DX HOT (Ibanez TS9DX Turbo Tube Screamer)==

See T808.

==TUBE DRIVE 3-KNOB (Butler Tube Driver)==

[[file:x_TubeDriver.jpg|150px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-tube-drv-based-on-butler-tube-driver-3-knob-and-4-knob-versions.123761/ Original forum thread]

The Tube Driver is one of those rare pedals that contains a real tube and uses it. It was originally designed by B.K. Butler, now [http://www.butleraudio.com/ Butler Audio], a keyboard player, to simulate an overdriven Hammond organ as heard in Deep Purple material. Eric Johnson used a Tube Driver into a Plexi when recording his classic [https://en.wikipedia.org/wiki/Cliffs_of_Dover_(composition) “Cliffs of Dover”] recording. Other famous users include Joe Satriani, David Gilmour and Billy Gibbons. The name of the unit can cause some confusion. We have the Chandler Tube Driver, the Tube Works Tube Driver and the Butler Tube Driver. Butler’s first prototypes were marketed by a 3rd party: Chandler. According to Butler, Chandler ran off with the design and began selling copies, excluding Butler from the deal. Butler then started Tube Works, later simply named Butler. The 4-knob version costs $299.

<blockquote>''“Actually the Chandler thing was a relatively minor incident in the overall history of my business activities. There’s not enough room here to elaborate much, but the truth of the matter is that somehow Chandler decided at one point that they had been the designer of the product, came up with the TD trademark and that I was infringing on their IP. They obviously had somebody attempt to copy the electronics and the physical design of my TD, then produced and sold them. I don’t know how many unauthorized units are out there. The mistakes inside are essentially within the EQ area and it would take too long to describe them. Also there is a basic ground loop mistake as well. The overall sound of the C copy is somewhat muted and not as clear on the upper harmonics, etc. Eric Johnson never used one of these copies as far as I know. All his pedals are ones I personally made. I never could understand why Chandler did that copy thing… They even challenged me in court and tried to convince the judge that Chandler was the actual owner of my design and the Tube Driver trademark. But the truth was obvious: In the end what was mine to begin with remains mine still… I then designed the black Real Tube pedal in 1986 which I still think is a superior pedal in some ways to the Tube Driver (ZZ Top’s Billy Gibbons agrees) and then went on to design all my Tube Works SKUs: MosValve, Tube Works Real Tube rack products, combo amps and reverb… then the smaller 3 knob version of the Tube Driver was designed in an attempt to give an entry level price to tube lovers. Actually I never completely stopped making original Tube Driver pedals, but just didn’t emphasize them so much during the early TW years. Later in about 1993 or 1994 I revived the pedal in earnest and named it after my ‘love on 4 wheels’, the model 911. Many will be glad to know that I’m now making a few new Tube Drivers per month again due to word of mouth ‘push’. They have better components than the original as far as pots, capacitors, etc. I still use metal Switchcraft jacks and they’re completely true to the original design.”'' Butler</blockquote>

<blockquote>''"There is NO Chandler Tube Driver… Never was a Chandler Tube Driver! They just marketed it for a while. But I do understand the confusion caused when I allowed their name to be included on my product. My lesson was well learned… enough said.”'' Butler</blockquote>

[http://www.kitrae.net/music/Music_mp3_Tube_Driver_Sound.html Kit Rae’s Tube Driver Page]

Original controls on the 3-knob version: Out Level, EQ and Tube Drive.
Original controls on the 4-knob version: Out Level, Lo and Hi EQ, and Tube Drive.

Eric Johnson (see pic) uses the 4-knob version into his Plexi (actually, 5 knobs because it has an additional Bias control) and turns off Bass and Treble completely. Like EJ, most players seem to prefer the 4-knob version of the real pedal because it is true to the original, according to Butler.

When it comes to Fractal Audio’s models, the 3-knob model is more of a favorite. It’s based on the entry-level Tube Driver, has more top end and its gain is more manageable. The models are featured in some factory presets. [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets Search this wiki page] for “Tube Drive” or “Tube Driver”. When turn down Drive to zero, there’s almost no output level. For cutting blues and rock tones, set Drive between 3 and 6 on the 3-knob version, decrease Tone and run it into a Fender amp model.

<blockquote>''"The 3-knob version sounds very different than the 4-knob version."'' [https://forum.fractalaudio.com/threads/tube-drive.72784/post-912764 Fractal Audio]</blockquote>

<blockquote>''"Both of my actual pedals go silent with the Drive set to zero as would be expected looking at the design."'' [https://forum.fractalaudio.com/threads/tube-driver-drive-block-issue.103122/post-1234847 Fractal Audio]</blockquote>

[https://www.youtube.com/watch?v=Q00e9xfg2L4 Texas Blues Alley] • [https://www.youtube.com/watch?v=hmvMI0sI0ME Jason Hobbs] • [https://www.youtube.com/watch?v=key38xruYaI shnobel] • [https://www.youtube.com/watch?v=Nx6cUuH7QGw Eric Johnson's rig rundown] • [https://www.youtube.com/watch?v=rxJT4OYFLYI Gearmanndude] • [https://www.youtube.com/watch?v=oOkfUHPOdUk BK Butler Tube Driver vs TS808] • [https://www.youtube.com/watch?v=BUfJPRG2DRg What's Inside This] • [https://www.youtube.com/watch?v=-LieE9JKqxo Tube Driver vs TS9 vs SD1] • [https://www.youtube.com/watch?v=VAELkuB6mEw Joe Perkins] • [https://www.youtube.com/watch?v=vUFrVhvN4Tg That Pedal Show] • [https://www.youtube.com/watch?v=lSVt5o26gBg Guitarsenal] • [https://www.youtube.com/watch?v=N_5qTxF39w8 Ibanez Tube Screamer or BK Butler Tube Driver (That Pedal Show)]

==TUBE DRIVE 4-KNOB (Butler Tube Driver)==

[[file:x_Tube4.jpg|150px]]

See above.

<blockquote>''"The model matches our reference pedal. I don't know when it was made but it's likely a later version because it has the "Bias" pot on the back. It has B. K. Butler's signature on the bottom. Some versions had a 10nF coupling cap before the first tube stage. Others had a 47nF cap. Our reference pedal has a 47nF cap. You can simulate the 10nF coupling cap by increasing the Low Cut control to 794 Hz.”'' Fractal Audio</blockquote>

==TUBE DRIVE 5-KNOB (Butler Tube Driver / Dean Markley Overlord)==

See above.

<blockquote>''"It's actually based on a Dean Markley Overlord.”'' [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-27-04-public-beta.210760/page-2#post-2635184 Fractal Audio]</blockquote>

The Dean Markley Overlord was built by Butler for Dean Markley, and is identical to Butler's 5-knob Tube Driver, the one Eric Johnson uses. The additional knob controls the bias of the internal tube.

[https://www.youtube.com/watch?v=IL-6lzSFweg Video]

==VALVE SCREAMER VS9 (Ibanez TS9 Tube Screamer)==

[[file:ts9.jpg|160px]]

See T808.

==ZEN MASTER (Hermida Zendrive)==

[[file:x_Zen.jpg|150px|left]]

[https://forum.fractalaudio.com/threads/fractal-audio-drive-models-zen-master-based-on-hermida-audio-lovepedal-zendrive.123767/ Original forum thread]

This model is based on the most famous “Dumble-in-a-box” pedal, designed in collaboration with Robben Ford to get thick “Dumblesque” tones from Fender amplifiers. Read more about Dumble amplifiers in the [http://wiki.fractalaudio.com/axefx2/index.php?title=Yeks_Guide_to_the_Fractal_Audio_Amp_Models Guide to the Fractal Audio Amp Models]. Gary Clark Jr. is another Zendrive user. The pedal was designed by Alfonso Hermida, a former airplane and NASA employee. These days Hermida has teamed up with [http://www.lovepedal.com/zendrive/ Lovepedal] to build his pedals ($240). The pedal excels at thick, creamy overdrive with lots of mids, but much different from a Tube Screamer. It’s very dynamic and responds well to the player’s attack. It works best with clean amps and many players prefer it with humbucker pickups.

<blockquote>''“The standard in dynamic, touch-sensitive overdrive pedals. Cut through the mix with the incomparable Zendrive. Inspired by a legendary guitarist, the Zendrive delivers blues, country, jazz and fusion tones associated with some of the finest, most costly amplifiers in the market. Four knobs control the overall volume, gain, tone and voicing of the pedal. At lower settings, the pedal offers extremely light overdrive sounds reminiscent of tube amps set near the “sweet spot.” At higher settings, the Zendrive increases in gain and sustain, producing tasty overdrive and low distortion tones.”'' [http://www.lovepedal.com/zendrive/ Lovepedal]</blockquote>

<blockquote>''“It always sounds scratchy during sound check, but once the band starts to play, it sounds great. It’s a mystery.”'' Carl Verheyen in [http://www.guitartonewizards.com/ Tone Wizards] </blockquote>

[http://www.premierguitar.com/articles/Hermida_Audio_Zendrive_Zendrive_2_and_Mosferatu_Review Review in Premier Guitar] • [https://www.thegearpage.net/board/index.php?threads/robben-fords-real-signature-zendrive.1424375/ Robben Ford’s Zendrive settings] • [https://www.youtube.com/watch?v=D0HIUT8J3I8 Robben Ford at TPS]

Original controls are: Vol, Gain (model: Drive), Tone (high cut) and Voice (cuts lows and controls the gain range). The Voice control is key to matching the pedal / model with the amp and guitar pickup. It tweaks the gain and bass response. Tone is a high cut, so turn it up. With a clean amp turn up Voice. Or run it into a dirty amp, with everything around 4 for a thick, searing and singing lead tone.

<blockquote>''"When I used the schematic on the web the model sounded nothing like my pedal. So I opened it up and made some measurements. The schematic on the web shows the Drive pot as being 500K but mine measures 1M. My feedback cap is 47 pF whereas the web schematic is 100 pF. Maybe when Lovepedal took over the build they changed some values. The model reflects our reference pedal.”'' Fractal Audio</blockquote>

The model is featured in some factory presets. [https://wiki.fractalaudio.com/wiki/index.php?title=Factory_presets Search this wiki page] for “Zen”.

[https://www.youtube.com/watch?v=jl8pTonea4M Sean Michael] • [https://www.youtube.com/watch?v=X-xaLMtSozM intheblues] • [https://www.youtube.com/watch?v=cIJ-NyEEfUk Session] • [https://www.youtube.com/watch?v=S0f5Ha34HNs That Pedal Show 1: Dave Kilminster] • [https://www.youtube.com/watch?v=fXSSE7SkDQg That Pedal Show] • [https://www.youtube.com/watch?v=czwbouXjlEU Pepe Navarro] • [https://www.youtube.com/watch?v=5w8iZmp8nF4 Sam Vilo] • [https://www.youtube.com/watch?v=LO-QZNeIBYU Robben Ford's Rig Rundown] • [https://www.youtube.com/watch?v=UWDeobr2MgE&t=10s Camilo Velandia: Original vs Modded vs Zendrive 2] • [https://www.youtube.com/watch?v=VvuN4HL6xUw Camilo Velandia: Axe-Fx Vs Zendrive] • [https://www.youtube.com/watch?v=UX-tLWb5aPE&t=1s gearmanndude 1] • [https://www.youtube.com/watch?v=qiTpUfQYUPw&t=2s gearmanndude 2] • [https://www.youtube.com/watch?v=eNWNogrlLXw Brett Kingman] • [https://www.youtube.com/watch?v=X6nXum4xjzw The SuperFunAwesomeHappyTime Pedal Show] • [https://www.youtube.com/watch?v=6SbwV8vx5LY Zendrive circuit experiment (Wampler)] • [https://www.youtube.com/watch?v=J7ZvluEep-Y Lovepedal vs Hermida] • [https://www.youtube.com/watch?v=WJN4DShTYxg Chris Buck] • [https://www.youtube.com/watch?v=ejeqhVMYXzg John Cordy] • [https://www.youtube.com/watch?v=pcSh5IZgE28 Robben's Settings] • [https://www.youtube.com/watch?v=SYMudmWJOCI John Cordy 1] • [https://www.youtube.com/watch?v=pC0oZz9-DiI John Cordy 2]

=Videos=

[[video:Cordy-Drives]]
[[video:Leon-StereoFuzz]]

[[category:Axe-Fx2]]
[[category:Axe-Fx3]]
[[category:FM3]]
[[category:FM9]]
[[category:VP4]]
[[category:AX8]]
[[category:FX8]]
[[category:Sounds]]
[[category:All]]

Impulse responses (IR)

2025-04-09T08:44:10Z

Komdosh: /* UltraRes */ samples should be a power of 2, so it is 8192 samples

__TOC__

=About Impulse Responses (IRs)=

To recreate the tonal characteristics of (mainly) speaker cabs, the [[Cab block]] and [[IR Player block]] rely on impulse responses (IRs).

An impulse response or IR is a collection of data that represents sound measurements taken from a speaker cabinet or system. A test signal is played through the actual speaker, recorded, and used to generate a profile which is stored as a file. The profile (IR) can then be used by an IR loader, such as the Cab block, and IR Player block (Axe-Fx only), to produce the sound of the speaker.

The terms "cab", "user cab" and "IR" are synonyms.

The Axe-Fx II also used IRs to reproduce the characteristics of specific microphones. This feature has been dropped in later firmware.

Most speaker IRs reproduce the tone of a speaker that was recorded with the microphone close to the speaker, aka "near-field" or "close-miked". [[I/O_connectivity_and_levels#Close-miking|More information.]] "Far-field" IRs represent the sound of a speaker that was captured at a long(er) distance. These IRs represent (to a certain extent) the "in-the-room" sound of a traditional guitar speaker, see below.

[http://en.wikipedia.org/wiki/Impulse_response Wikipedia: impulse response]

From the [[Owners Manuals]]:

<blockquote><HR>
<blockquote>
Fractal Audio Systems speaker simulation technology is incredibly accurate, yet some listeners find the sound of IRs unfamiliar at first. This is because impulse responses typically recreate the sound of “close miking.” When you mic a guitar speaker, the mic “hears” something very different to what you might hear. Our ears are by definition “neutral” whereas a mic has distinct “color.” We typically listen at a distance (and speaker tone is very different as we move around) while a mic is inches away and stationary, focusing on the desirable sound at a specific spot.
As guitarists, we are accustomed to the sound of a speaker “in the room,” but this is not what our audiences hear. For recording and performing, the close mic’d sound is essentially a universal standard. THIS is the sound that the Cab block is designed to reproduce, and this explains why not only guitarists, but recording and front-of-house engineers have embraced its use. (Of course our Amp models can also be used with a traditional guitar speaker as demonstrated in many of the rig designs in Section 1: Setting Up).
If you are new to using mics on a guitar amp, you will find the Cab block is a fantastic way to learn more. To get started, listen to single IRs, or explore the factory presets which combine several at once. For almost a century, artists, producers and engineers have honed the craft of placing or blending mics to achieve a desired tone. Many classic techniques are easy to recreate. Try a tried-and-true “recipe” blending one “bottomy” and one “bright” mic, or try something totally original.
The factory content includes dozens of speakers with multiple different mics in different positions. You may also enjoy “Mix” IRs by Fractal Audio or 3rd-parties, which bring a producer’s experience to you in a single IR. In any case, recognize that the sound of IRs is the very sound of the speakers and mics they capture.
</blockquote>
</blockquote>

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>

<blockquote>
An IR stands for "Impulse Response". In mathematical terms it is the time response of a system to a Dirac delta function (also known as an impulse). An IR can be used directly as the coefficients for an FIR (Finite Impulse Response) filter. In the modeling world IRs are obtained from real speakers and when processed using an FIR filter produce extremely accurate results. In essence an IR is a "sample" of the speaker and microphone and uses very similar principles. However the quality of any IR is subject to the talents of the individual(s) capturing the IR. Mic placement, preamp choice, etc., etc. are important as you are essentially recording the speaker. In the old days modelers used EQ to emulate speaker response but I don't think there are many left that still use that technique. So the quality of the IR is really the issue here. The original Axe-Fx pioneered this technology which has since become almost ubiquitous.
</blockquote>

<blockquote>
[https://www.thegearpage.net/board/index.php?threads/has-anyone-cracked-open-an-ir-to-see-what-all-its-really-doing.2037093/#post-28343491]
It's analogous to a sampler. Consider the sample of, say, a kick drum. You make a short recording of that and then "trigger" that recording. If you want the kick drum louder you make the trigger louder. Now assume you trigger that recording thousands of times a second at varying amplitudes. That's essentially how IRs and convolution work. You trigger the recording at the sample rate and each playback is weighted by the sample amplitude.
</blockquote>

<blockquote>
[https://www.thegearpage.net/board/index.php?threads/jason-sadites-video-claiming-proving-that-an-ir-is-nothing-but-just-a-static-eq-curve.2256176/post-32574997]
An IR is the coefficients for a Finite Impulse Response (FIR) filter. A classic EQ is an Infinite Impulse Response (IIR) filter. FIR and IIR are both filters which we call "equalization" in the audio realm. You can design an FIR using various techniques. These techniques yield the coefficients for the filter. Another way to obtain the coefficients is to "sample" them from a linear system. You can approximate an FIR filter with an IIR filter. There are techniques for creating a cascade of second-order sections (SOS) from an FIR filter (Prony's method is one).
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/why-do-some-irs-and-dynacabs-seem-to-compress-more-than-others.202405/page-2#post-2532466]
EQ curve" is semantics. It's a filter. In this case usually an Infinite Impulse Response (IIR) filter. There are two types of filters: Infinite Impulse Response (IIR) and Finite Impulse Response (FIR). An "IR" as we use the term is an FIR. It's a filter and, hence, could be said to be an "EQ curve".

The name "filter" arose because it filters out certain frequencies and lets others pass. Both an IIR and FIR accomplish this. The difference is that an FIR has no poles, only zeros. An IIR can have both poles and zeros. An IIR can achieve similar performance to an FIR with a lower order thus making it more efficient to implement. IIRs, however, typically have nonlinear phase response whereas an FIR can be linear phase.

</blockquote>
</blockquote>

=IR properties=

==File formats==

Capturing IRs creates WAVE files (.wav). WAVE files can be converted into SYX (MIDI System Exclusive) files using [[Cab-Lab]] or the Fractal Audio's current editors. When using Cab-Lab to convert WAV files, and when using IR Capture to create IRs, two files are created: an IR file (.ir) and a SYX file (.syx). The .IR file is raw IR data which can be imported into Cab-Lab for mixing purposes. Cab-Lab is the only application that can handle .IR files.

==Sample rate==

Impulse responses are tied to the sample rate of the processor. Fractal Audio's modelers are set to a fixed sample rate of 48kHz.

Read this: [[Digital_I/O_and_audio#Sample_rate_is_fixed_at_48kHz|Sample rate]].

==Auto Trim==

This removes superfluous leading silence from the start of the IR. Many commercial IRs do not require this. It might come in handy when shooting your own IRs using [[IR Capture]].

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/what-to-do-when-you-can’t-line-up-irs.146531/post-1733402]
There is no wrong place to trim. It's impossible to know where the data starts because of noise. So we find where the data starts to increase, back up a few samples and trim there.
</blockquote>
</blockquote>

==Minimum Phase Transformation (MPT)==

This verifies that the phase of the IR causes no issues when mixed with other (MPT) IRs, by time-aligning the IR. This is especially important when you mix multiple IRs and you don't want to align them manually in Cab-Lab, in the DAW or on the Axe-Fx III hardware. All legacy factory cabs are MPT (Minimum Phase Transformed) to make them mix-compatible. When neither Min Phase or Trim has been applied, the impulse response is considered "raw", containing the original phase details.

[[Cab-Lab]] and the editors let you apply MPT or Auto Trim when importing files, manually or automatically.

Current firmware lets you align multiple IRs in the Cab block manually. Read this: [[Cab_block#Align|Cab block: Align]]

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>

<blockquote>
[http://forum.fractalaudio.com/threads/minimum-phase-how-does-it-affect-the-sound-of-an-ir.141597/#post-1684780]
If it's a cab IR the difference is basically nil because a speaker is a minimum-phase device. All minimum-phase does in this case is automatically remove the leading silence. A room IR is not minimum phase so you should not use MPT when processing a room IR.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/phase-problem-with-imported-oh-cabs.144009/#post-1704419]
The factory cabs are minimum phase for precisely the reason that mixing non-minimum phase leads to phase problems.
</blockquote>

<blockquote>
All the factory cabs are minimum-phase transformed so they are, by definition, "in phase" with each other.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/non-minimum-phase-irs.146046/]
So I've been doing a lot of critical listening the last couple months and have come to the conclusion I like non-minimum phase IRs better. The difference is subtle. They don't really sound that different but there are differences in the attack and in the feel. They just sound/feel a little more open and realistic. Another thing is that they mix very differently. It's less predictable but more natural. The caveat is that it's like mixing real mics, you need to experiment moving each mic in and out whereas with minimum phase you can usually just leave one mic at zero and move the other in and out. So here's a [http://www.fractalaudio.com/downloads/firmware-presets/axe-fx-3/Wellspring_NonMP.zip zip file] of my favorite IR session, the Wellspring session, in non-min phase format for use with the Axe-Fx III. My suggestion is to put them in one of the user banks and compare with the factory min-phase versions. Note that names are a bit different but you should be able to figure it out.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/non-minimum-phase-irs.146046/page-2#post-1727265]
Minimum vs. non-minimum phase changes the "delay" of the individual frequency components of the waveform. In a minimum phase system the individual sine waves have the least phase possible which concentrates the energy near the start of the waveform. For example consider a sine wave with an isosceles triangle envelope. The energy is concentrated at the center of the waveform (at the apex). The Fourier transform of that is mostly the primary frequency with a bunch of other sine waves at various amplitudes added. We can phase shift the component sine waves and the magnitude (frequency response) will not change but the waveform will. If we make it minimum phase the sine waves will add up so that the energy is concentrated at the beginning of the waveform and the waveform will then look something like a sine wave with a right triangle (ramp down) envelope.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/ir-length.155295/post-1848242]
I've long maintained that a guitar speaker is essentially a minimum-phase device and that the benefits of MPT'ing the data far outweigh any minuscule differences in the IR phase response (the magnitude response is identical).
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/ir-length.155295/post-1848701]
Raw is technically "better" but the difference between raw and MPT is minimal. The disadvantage of raw is that you have to manually align them if you are mixing IRs.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/aitr.176587/post-2145066]
FullRes IRs can be processed with minimum-phase or auto-trim, if desired. However, minimum-phase is not recommended as this will tend to destroy the reflection information.

</blockquote>
</blockquote>

DynaCabs are always time-aligned (but not minimum phase) without destroying phase information, allowing them to be mix-and-matched. You can mix-and-match IRs from different cabs/mics and they'll always be perfectly aligned. They have 0.3 ms of leading silence.

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/fm9-latency-around-5ms.200203/page-5#post-2498733]
It's because they are not minimum-phase transformed.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-22-00-public-beta-beta-6.193187/post-2402312]
The files are initially aligned to the same reference point -- a universal standard across all DynaCapture IRs. In other words, IRs for mics that are farther away have been time compensated to be aligned with IRs for mics that are closer. You can use the controls on the Align page in the usual way, however, to add time to any individual IR.
</blockquote>
</blockquote>

=IR resolution=

Fractal Audio's amp modelers and software support impulse responses of various lengths. This is also referred to as: resolution. This is measured in samples or milliseconds. The number of (milli)seconds of an IR is calculated by dividing the length (in samples, aka points) by the sample rate. All Fractal Audio devices are set to a fixed sample rate of 48000 Hz. Read this: [[Digital_I/O_and_audio#Sample_rate_is_fixed_at_48kHz|Sample rate]].

The Axe-Fx III, FM9 and FM3 let you edit the length of a legacy IR in the [[Cab block]] (hardware and editor). This affects CPU usage (longer = more CPU usage). The Axe-Fx III also lets you do this to DynaCabs (FM3/FM9: n/a).

==Normal (Standard)==

The number of samples is 1024 samples (1K), 20 ms.

However, the Axe-Fx III refers to 2K IRs (40 ms) as Normal IRs.

1024 samples suffice to capture the essential sound of the speaker cabinet, without so-called room reflections. In general, you can use Normal Res without having to worry that the sounds is not as good as HiRes or UltraRes. "Normal" is also referred to as: "Standard".

1K is the default IR length in the FM3 and FM9.

<blockquote>
'''FRACTAL AUDIO QUOTES'''
<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/red-wirez-cab-impulses.20808/page-12#post-350947]
99% of the information in a cabinet impulse response is in the first few ms. 1024 samples is more than enough to capture the essence of the cabinet and much of the room mics. You don't need a DAW, simply send the sysex files to your Axe-Fx.
</blockquote></blockquote>

==HiRes==

2048 samples, 40 ms.

Double the length of the "normal" IR, allowing it to store more information after the first 20 ms. HiRes IRs use more CPU than Normal Res, and also more than UltraRes. Because of this, HiRes as a label / format was discontinued, although the Axe-Fx III still supports it (the Axe-Fx III refers to 2K IRs (40 ms) as Normal / Standard IRs).

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/axe-fx-ii-technical-questions-thread.35997/page-45#post-495810]
There are a couple reasons for 2048. Probably most important is that it allows 1024 in stereo mode. To be able to do stereo 1024 requires a 2048 convolution engine. Secondly, some IRs benefit from longer IRs. Better to have the ability and not need it than the converse.
</blockquote>
</blockquote>

==UltraRes==

Up to 8192 samples, 170 ms.

UltraRes speaker IR processing is a Fractal Audio proprietary technique which enhances the spectral resolution of an IR without adding CPU burden or storage requirements. UltraRes IRs allow more information to be captured than Normal or HiRes IRs, especially in the lower frequencies. UltraRes IRs require more CPU power than Normal Res but less than HiRes. UltraRes lRs are displayed in italics or in a different color in the software editors.

About UltraRes IRs:

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>

<blockquote>
The problem with conventional IRs is that they are too short to capture the detail in the low frequencies. There are those that maintain 20 ms is the maximum length you need to fully replicate the speaker. This would be about 1000 samples at 48 kHz. I disagree with this as I have many IRs here that exhibit significant energy beyond 20 ms. I believe the room has some influence as the low-frequency modes of the room will impact the resulting sound. The amount of this impact depends on the room, the mics, distance, etc., etc. Or perhaps certain speakers have particularly high Qs in the low frequencies. Regardless, it is my opinion that you need IRs much longer than 20 ms to fully capture the "mic'd amp in the studio" sound. My tests show that IRs of 8000 samples are required to fully capture the low-frequency detail. Unfortunately to process an 8K IR in real-time require copious processing power... Fortunately I have developed "Ultra-Res" cabinet modeling. Ultra-Res cabinet modeling provides the frequency detail of a very long IR with little or no added processing power requirements.

Existing IRs will still be processed as usual. Ultra-Res IRs will be tagged as such which will indicate to the processor to use the new processing algorithms. Note that Ultra-Res IR data is not conventional IR data.

The frequency resolution of an IR is the sample rate divided by the number of samples in the IR. The window function has nothing to do with frequency resolution (except for making it even less). So a 1K IR at 48 kHz sample rate has a frequency resolution of roughly 48 Hz. If a speaker has a resonance (formant) at, say 80 Hz with a Q of, say, 3.0, then 48 Hz is insufficient to capture that resonance accurately. You need a frequency resolution of several Hz to accurately recreate that resonance. I chose 80 Hz and a Q of 3 because that's what that response looks like. The Q could even be higher than that. It doesn't take much mental energy to realize that if you have a narrow formant at a low frequency then you need fine frequency resolution to reproduce that. An 80 Hz formant with a Q of 3 only spans about 25 Hz. Obviously a frequency resolution of 48 Hz is not going to be able to reproduce that. Windowing only smooths the response even more. This is basic FFT theory. The less time-domain information you have, the less frequency domain information you have and vice-versa. This is the uncertainty principle. I always window IRs with a Hann window.

Another way to look at it is to think in terms of formants. That particular speaker has a pronounced 80 Hz formant. It takes well over 100 ms for the energy of that formant to decay to the point of imperceptibility. Obviously a 20 ms IR can't reproduce an event that occurs for over 100 ms. Here is a zoom of the original non-minimum-phase IR (IOW raw time response)... (see thread for image). You can clearly see the 80 Hz formant. There are some room reflections but they are very small. The 80 Hz formant starts well before any reflections. It's obviously a high-Q resonance as it rings for quite a while. The higher the Q, the longer it takes to decay.

Here's another example. (see thread for image) This is one of the new OwnHammer IRs. The IR is OwnHammer_412_MAR-CB_D-120_SS_RBN-121. These IRs are 100 ms long (4800 samples). I windowed the original IR to 4K to prove a point. The blue trace is the original IR (windowed to 4K samples). The green trace is the "typical" 20 ms IR (windowed to 1K samples). The red trace is the Ultra-Res version.

The problem is that human perception is logarithmic and IRs are a linear process. 48 Hz resolution is way more than necessary at, say, a few kHz but not nearly enough at low frequencies. The brute force solution is to use very long IRs, 8K or more. Ultra-Res solves this in a novel way that uses little to no extra processing power and no additional latency.

Normalization is your friend. Rectangular windows are simply truncation and are generally regarded as bad practice due to extremely high sidelobe levels. The choice of window is subjective. I actually use my own custom window that is not really a Hann window but that's proprietary information. My window preserves more frequency detail while still suppressing Gibbs phenomenon. Windowing trades off frequency resolution for sidelobe suppression. My window is optimized for the unique statistics of IRs. For a random process I tend towards Bessel-Kaiser windows. IRs have unique statistics that aren't addressed by any of the standard textbook windows.

Let me state these points:
# We don't record guitar amps in airplane hangers or anechoic chambers. We record them in studios.
# When we record a guitar amp we carefully set the amp up in the studio to get the best sound "on tape". This involves moving the amp around, placing gobos, etc. When we collected the Producer's Packs IRs we spent hours arranging the amps/speakers, mics and gobos and playing through the amp and readjusting until we were satisfied. This also included adjusting the preamps and mixing board. In one studio we found that we got the best tone raising the cabs off the floor by a couple feet, orienting them towards a particular wall and placing gobos behind (this was the engineer's standard recording arrangement).
# At this point our objective of the IR is to capture the sound of that amp/speaker at that position in the room, with the gobos, mics, preamps, etc., etc. The goal is not to capture the raw sound of the amp/speaker in an airplane hanger or outside using a ground-plane measurement and measurement mics. That might be someone else's goal but it is not ours. IOW our goal is to treat the cab, mics, preamps, room, etc. as a whole, as a good engineer/producer would.
# Subsequent analysis of the data shows that there is significant energy out to 100ms and even beyond. However there is little energy beyond 200 ms or so (as it should be in a well-designed studio). This observation was the catalyst for the Ultra-Res algorithm. There are other observations about the statistics of the data that I cannot disclose.
# Some cabinets displayed noticeable resonances at low frequencies. Others did not. The frequency of these resonances were not consistent and, not coincidentally, matched the measured resonance of the impedance sweep. It is a logical conclusion, therefore, that the resonance was NOT caused by the room but by the speaker/cabinet combination. Furthermore a plot of the group delay for the raw data showed that the delay of the resonance was too short to be a room mode. Regardless, whether the resonance is from the speaker or room or mics or preamps is irrelevant. All we care about is recreating the sound of that speaker as it would be recorded as accurately as possible.
# Truncating an IR destroys information by definition. We don't care where the information comes from, be it the speaker or the room or the mics or the preamps. We want all the information. If a plot of the frequency response of a truncated IR differs considerably from the non-truncated version then we have lost information and concomitant accuracy.
# NO ONE producing commercial IRs records them in an airplane hanger, for obvious reasons. The best ones are done in a studio using the same technique we used for the Producer's Packs: setting up the cab, adjusting the position, mics, preamps, etc. and playing through the amp/cab and readjusting until the best tone is achieved. The new OwnHammer IRs are an example of this. Many, if not all, of those IRs exhibit significant energy to 100 ms (and likely beyond but the data stops at 100 ms). Truncating them to 20 ms destroys vital information. You can argue the semantics all day long. I've compared truncated and non-truncated and the difference is clearly audible. It is especially noticeable when chugging power chords. You can hear the resonance. It goes "bonggggggg" as opposed to "thuk". Most importantly it sounds "better" IMO.
# Ultra-Res is an algorithm that markedly increases accuracy. It gives the frequency resolution of a 200ms IR without additional processing overhead and no added latency.

Ultra-Res is especially powerful in Tone Matching applications, particularly real-time matches and was another impetus behind the development.

The myopic only see the IR as a capture of the speaker's "unadulterated" response. As I stated before I believe the future is treating IRs as capturing the entire recording chain including mics, preamps, etc. and have pushing in that direction. We have already seen the fruits of this labor in the Producer Pack and OwnHammer V2 IRs. We used mainly PP and OH IRs at Axe-Fest this weekend and the results were stellar. Andy Wood's tone was among the best guitar tones I've ever heard live and we dialed it up in 10 minutes under far less than ideal conditions. It consisted of the Two Rock amp model and the EV 12L Mix IR. When you include more than the speaker response in the IR you can have low-frequency resonances that persist for tens of milliseconds or more. Truncating an IR destroys this LF information. In many cases this LF information loss would probably not be perceptible. In other cases, from experience, it can be extremely noticeable. The bottom line is that you can always remove the information if you don't want it but you can't add back what isn't there.

Let me phrase this another way. An IR can consist of the "raw" speaker response plus none, one, some or all of the following: mic, preamp, room, power amp (e.g. you want to capture the response of a tube amp driving the speaker), etc. If you only care about the raw response then a short IR is all that is required. However if you want any of the other elements as part of the IR then a longer IR may be necessary. Ultra-Res gives you the OPTION of processing longer IRs.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/firmware-13-beta-feedback.80939/page-2#post-983190]
If the .wav is only 40ms long there is no sense in converting to Ultra-Res as you won't gain anything. Over 80 ms is desirable. The maximum length supported is 170 ms or so. Anything longer than that is truncated to 170 ms.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/can-current-cab-lab-process-ultrares-irs.81388/post-989024]
To get the optimum results the length should be 170 ms or more. As the length gets shorter you'll lose information. However there may not be any information to lose. It all depends on the IR. I've seen long IRs where only the first 100 ms or so is actual information and the rest is silence. OTOH I've seen 100 ms IRs where there is obviously more information but it got truncated. You lose nothing with Ultra-Res except the ability to change the size of the cabinet. You gain better sound and less CPU." "You can't mix Ultra-Res IRs as the data is not compatible. However... we foresaw that and the UltraRes conversion process produces two files: a .ir file and a .syx file. The .ir file is the raw IR data that can be imported into CabLab for mixing purposes. So CabLab can take .wav, non-Ultra-Res .syx and .ir files as input to the mixer section and product Ultra-Res .syx files." "The .ir files are included with our cabinet packs. We will not be offering .wav files. If you have the .wav file you don't need the .ir file. A .ir file can ONLY be used with CabLab. If you use the Axe-Fx II to capture IRs it will only generate .ir and/or .syx files. No .wav files are generated. The resulting data can only be used on Fractal Audio products.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/nothing-beats-the-tv-mix-cabs-not-even-ultrares-opinion.84551/page-3#post-1027747]
It depends on the IR. Ultra-Res improves low-frequency resolution. It is very apparent with some IRs and virtually inaudible with others. It all depends on the low-frequency formants in the original IR. If there are significant, high-Q formants Ultra-Res will preserve those whereas conventional, short IRs will not. Audibility also varies with the amp being used. The difference is more audible with high gain as this will excite the formants more. Low-frequency formants vary with the type of cabinet and speaker. Some cabinets have a smooth low frequency response. Others have prominent formants. The mic also has an impact. Some mics will accentuate the formants. The room also contributes if it has strong LF modes. Furthermore some people like to capture an IR using a tube power amp. In this case you WILL get a significant formant at the low-frequency resonance of the speaker. A conventional IR will not capture that as the Q of the formant will exceed the resolution of the IR. Ultra-Res will capture that formant as Ultra-Res has 8 times the low-frequency resolution. Those who claim they can't hear a difference are correct. They can't. It's nothing to be ashamed of. But because they can't doesn't mean others also cannot. I can clearly hear the difference but I've trained myself on what to listen for. I vastly prefer Ultra-Res and only use Ultra-Res IRs in my personal patches (aside from the TV Mix, which is just a magical IR).
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/the-difference-between-170ms-and-500ms-ir-lenghth.126770/#post-1508992]
The length of the sweep only determines the signal-to-noise ratio. If the room is completely silent the sweep can be infinitely short (an impulse). To overcome ambient noise you need more energy in the applied stimulus. With an impulse you can only increase the power so much before the amplifier or the speaker or the mic or the preamp, etc. distort. However, if you spread that power out over a longer period of time you can increase the energy and therefore increase the SNR. Think of it this way: a 1 ms pulse at 1000W has the same energy as a 1 second pulse at 1W. Now you can't just put a 1 second pulse into a system because the pulse has little frequency content. A 1 second sweep over the band of interest allows the transfer function (IR) of the system to be obtained via deconvolution. There are other signals you can use like pseudo-noise and MLS sequences but a "chirp" has the best characteristics. In the early days of room IR capturing they used impulses generated by popping a ballon, firing a starting pistol or clapping two boards together. The results were poor due to low SNR. This lead to the development of signals that have higher energy. To get the IR of a room long sweeps are typically used because there is a lot of ambient noise and the "returned signal" is weak (the reverb portion of the response is very low compared to the direct signal). When close mic'ing a speaker the ambient noise is low and the signal strength is very high so a short sweep is adequate. In fact you could probably get away with 100 ms or less in a studio environment.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/the-difference-between-170ms-and-500ms-ir-lenghth.126770/#post-1509021]
I've never seen a cabinet IR (and I've examined thousands) that has any significant content beyond 150 ms or so. Most cab IRs are under 40 ms. The exception to this would be a "room IR" where the mic is very far from the speaker and the room is significantly reverberant. But one wouldn't normally use that as the primary tone, instead to add a little ambience to the tone and the loss of information would be imperceptible in context. Modeling products typically use IR lengths of 1K samples as this covers 90% of IRs ever captured. We support 2K and Ultra-Res (which is equivalent to 8K) which covers 99% of IRs. The amount of CPU power required to process an IR is proportional to the length of the IR. To support a 500 ms IR (24,000 samples) would require over ten times the CPU power of a 2K sample IR. It also requires over ten times the memory for storage. Given that that vast majority of IRs do not have any information beyond 40 ms it is wasteful of CPU and memory resources to support IRs longer than 2K.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/why-are-fas-irs-truncated-to-170ms.127313/#post-1514597]
The length of time you hold a chord is irrelevant. The impulse response of a speaker cab is typically much less than 100 ms. Only when there is significant room reflections is the length greater. Then you get into the whole argument of whether the IR should contain any room information.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/firmware-13-beta-feedback.80939/page-2#post-983217]
(Tone Matching and Ultra-Res) In Realtime mode the raw internal IR length is 8K which you can dump.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/firmware-13-beta-feedback.80939/page-2#post-983211]
You can export the Tone Match to CabLab and create and Ultra-Res IR.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/why-i-wont-be-using-the-cab-block-for-recording-any-more.98578/page-5#post-1182690]
I'm a huge advocate of longer IRs. In fact I think I was the first to advocate it despite all the naysayers. I pushed OwnHammer (and others) to increase their IR lengths and they were the only ones who acted on that advice (so far, maybe the other guys will start to follow suit). Ultra-Res was born out of the desire for longer IRs.

For recording you don't need to use the cab block in the Axe-Fx though. Record the raw amp sound and then "re-cab" it later. This way you can try different cabs. Cab-Lab is great for this. Cab-Lab does not do UltraRes processing. It creates UltraRes files for the Axe-Fx but it does all processing at the full IR length up to 8K samples. You can use other convolution plug-ins as well.

The reason for UltraRes is that long IRs have several drawbacks:
# They require lots of storage space. Not an issue on a computer but on a hardware product that means expensive non-volatile memory.
# They require lots of processing power if you don't want any latency. On a computer it doesn't matter since latency is a non-factor if you are processing prerecorded tracks. On a hardware product we must have zero latency.

So UltraRes was devised as a way to exploit the statistics of the data to give the benefits of longer IRs without the usual hardware drawbacks.

In my tests I've found that 8K samples (170 ms) is more than enough. I think 500 ms (24K samples) is overkill and if an IR has significant energy out that far then it has too much room in it. The speaker and cab itself are never more than 100 ms, usually much less. Anything beyond that is the room. I personally don't like IRs with lots of room in them. A little bit of early reflections are nice and make things sound less direct but too much room makes the sound get lost in the mix.

There's no meaningful data beyond 150 ms and if there is, it's the room and you don't want that much room.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/axe-fx-ii-quantum-2-00-public-beta-deux.109702/page-19#post-1314753]
(Ultra-Res 2.0) No big deal, just some improved processing algorithms. The UltraRes cabs in Quantum 2.0 were all reprocessed with UltraRes.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/cab-lab-3-3-0-released.112286/]
UltraRes 2.0 is the next level of evolution for our patent-pending speaker simulation technology, with even greater accuracy than the original version. UltraRes 2.0 cab files are backwards compatible with previous Axe-Fx and AX8 firmwares supporting UltraRes 1.0.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/low-cut-high-cut.119906/page-4#post-1426474]
"1" from the speaker is the near field. The response of a speaker in the near field is very different than the response in the far field. In the near field the response changes (drastically) across the face of the transducer. Even moving the mic a fraction of an inch will result in a very different sound. 10 ft. from the speaker is the far field and the response changes smoothly as you move across the field. If the near field were the same as the far field then the sound wouldn't change as you moved the microphone and you could place the microphone anywhere on the face of the speaker. Anyone who has mic'd a speaker knows that this isn't the case.
</blockquote>

<blockquote>
[http://www.thegearpage.net/board/index.php?threads/impulse-response-quality-no-difference-between-200-500-low-high-etc.2015600/#post-27950543]
The energy of the speaker itself is contained in less than 50 ms. Anything beyond that is room reflections. Therefore any differences that you may hear are room reflections. The question then becomes do you want room reflections. Some say yes, some say no. One approach is absolutely no room reflections and then you add them with room simulation. The other approach is to use longer IRs with reflections in them. Both are valid approaches. Close mic'ing minimizes room reflections as the direct path is much shorter than the reflections path and sound pressure decreases by the square of the distance.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-version-5-08.150760/page-4#post-1793546]
The length doesn't determine the amount of bass. It determines the resolution. If there is a sharp resonance in the bass response a short IR will smear that resonance causing it to be wider than it actually is.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-version-5-08.150760/page-2#post-1793085]
It's complicated. Some people claim you don't need any more than 20 ms. For many cabs this is true. It depends on the "formants". A guitar speaker is approximately "constant Q" and minimum phase. The peaks and dips are caused by formants and the Q of those formants is roughly constant. This means low frequencies take much longer to decay than high frequencies. I've measured some cabs with a low frequency formant that takes much longer than 20 ms to fully decay. This is the whole reason for Ultra-Res. There are no absolutes. Many cabs can be captured just fine with 10-20 ms. Others need more. If you want some of the room in there then you need more.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/ir-length.155295/post-1848227]
I've been experimenting with IR length lately and keep finding that I like a shorter length. So I gave some thought to it and I think the reason is that a shorter IR trims off the early reflections. A 1024 sample IR is over 20 ms. If there is a wall 5 ft. away that puts a reflection smack dab in the middle of the IR. The Redwirez IRs you can see (and hear) the ceiling reflection pretty clearly (ceiling was probably about 8 ft). Using a shorter IR removes that reflection. I've actually been turning down the IR length lately on my personal patches, typically 512 samples, as I find it makes the IR "clearer". While the push in the industry has been towards longer and longer IRs I'm not sure that's a good thing unless you are careful with your IR capture to ensure that you aren't capturing reflections. Some IRs, particularly ported bass speakers, may need the longer length to capture the low end with sufficient detail but the average guitar cab is probably fine at 512 or even less samples. Heck, prior to the original Axe-Fx some products were even using 128 samples.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/ir-length.155295/post-1848298]
SOMETIMES shorter is better. It depends on the environment they were captured in.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/ultrares-irs.158416/post-1893051]
FWIW, I almost always reduce IR length on my personal presets. Usually 512 or 1024. I like the lack of reflections.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/ir-length.155295/post-1849075]
The takeaways from this are simple:
# Minimize reflections as much as possible when capturing IRs. Shoot them in the largest room you can find. Elevate the speaker off the floor or angle it back to minimize the floor reflection. Make sure there is ample distance behind an open-back cabinet.
# For existing IRs that may have prominent room reflections try different IR lengths to trim out the reflections.

</blockquote>
</blockquote>

About Far-field IRs:

"Far-field" IRs represent the sound of a speaker that was captured at a long(er) distance. These IRs represent (to a certain extent) the "in-the-room" sound of a traditional guitar speaker. There are a couple of far-field IRs among the legacy stock cabs, created by Jay Mitchell ("JM"). Also, Fractal Audio has released far-field IR libraries ("Far-Field Sessions").

"FullRes" IRs also capture longer distances, but these are intended to capture the room, where "far-field" IRs are aimed at capturing the sound coming directly from the speaker at a longer distance. More about FullRes below.

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>

<blockquote>
[https://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/post-1799610]
Far-field IRs are not the panacea some are making them out to be. Some things need clarification:
# A far-field IR will still not sound exactly like "amp in the room". The reason for this is that the dispersion of a guitar cabinet is very different than that of a FRFR speaker. An FRFR speaker has far wider dispersion at high frequencies, by design. With a guitar cabinet the low frequencies are less directional than the highs. This causes the cab to interact with the room differently. So even if you capture a far-field IR it will not sound the same through a FRFR speaker.
# Most of the time we are not in the far-field of a guitar cabinet. At 10 kHz the far-field of a 12" speaker is about 18 ft. So usually we're in the far-field at some frequencies but in the Fresnel zone at others. At a typical distance of, say, 5 ft. we are only in the far-field at frequencies below roughly 3 kHz. Above that we are in the Fresnel zone.
# Because of #2 the sound at each ear can be quite a bit different. That six inches or so between our ears makes a big difference. When using a far-field IR the same sound will be presented to each ear. Even when in the far-field the sound changes pretty dramatically vs. angle because the dispersion is a function of frequency. One ear will hear more highs than the other.
# A cab with more than one speaker creates significant challenges. For example, a 4x12 has a far-field at 10 kHz that's roughly 100 feet! If you capture an IR of that cab at, say, 10 feet you are nowhere near the far-field. At anything other than nadir (aka boresight, 0 degrees) the individual speakers will contribute with different times of arrival. This results in extremely phasey sound (we were able to get some 4x12 IRs by using a special trick but in general you need to be very far away).
# We don't hear this phasiness when listening to the real cab though because of #2. We get very different signals at each ear and our brain processes these. When using a Fresnel-zone IR of a 4x12 the same signal goes to both ears.
# Many guitar cabs are open back. A far-field IR of an open back cab through an FRFR monitor will sound very different because you're not reproducing the sound coming out of the back of the cab and bouncing off the walls.
# The sound of recorded guitar is near-field. This is what most people are used to hearing. So if you're trying to get the sound of your favorite record you won't get that with far-field IRs.

The takeaway from all this is that if you truly want the sound of amp in the room the best way to get that is to use an actual guitar cab. This isn't to say that far-field IRs are useless. They will give you a roughly similar sound to a guitar cab but it's just not the same.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/post-1801544]
One of the things I've found really useful about these (far-field IRs) is they are a good starting point for dialing the amp block in. Near-field IRs can have excessive bass and/or treble. To compensate we might end up doing strange things in the amp block which throws off the distortion character and feel. When using a far-field IR it's very similar to how the amp sounds through a conventional cab. So what I'm doing is using one of the far-field IRs to start, dial in the amp block and then choose a near-field IR. I then adjust the low/high cuts in the cab block rather than adjusting the amp block.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/aitr.176587/post-2148312]
A far-field measurement is only the response of the transducer. There's a couple ways to do far-field measurements:
# Suspend the speaker and mic in air far enough above the ground so that the ground reflection arrives after the direct signal.
# Use a ground plane measurement technique outdoors or in a space large enough that any reflections arrive after the direct signal.
A room mic is completely different and it will have the room reflections, which are desirable and give the mix "space". It will also have the response of the mic "baked in".
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/post-1822542]
# Close-micing a cabinet is not problematic. It's been done for years and solves a lot of technical issues. It may sound different than listening to that cabinet at distance but it's no more right or wrong than any other micing technique.
# Far-field has nothing to do with the picking up the sound from multiple speakers and "hearing the sound of the cab as a whole". Many cabinets have only one speaker. The far field of an acoustic radiator (i.e. speaker) is the point where the sound waves coming from the speaker behave as though the radiator is a point source. In the far field the intensity falls off by the inverse square of the distance. At distances less than the Fraunhofer distance the field is characterized by widely varying intensity due to interference. To calculate near field beam patterns you can treat the transducer as a lot of smaller point sources and find the contribution of each point source at a given point. As you move around in the near field each point source has a different phase and intensity due to distance and angle. This interference causes the intensity to vary widely as you move around.
# You can measure the far field response of a speaker in a number of ways. One way is a free field measurement. The speaker and mic are suspended far above the ground so that the multipath from the ground occurs after the direct path IR has decayed fully. This is obviously difficult. Another way is using a ground plane measurement. The microphone is placed on a smooth hard surface either outside or in a large enough room so that any reflections occur after the direct path IR has decayed. Placing the mic on the floor effectively removes the floor reflection as the direct path and reflected path are the same.
# There is no such thing as a "short impulse". An impulse is, by definition, infinitely short. Regardless, impulses are almost never used to measure IRs. Almost everyone uses sine sweeps or other wideband waveforms (PRN sequences, etc.). The length of the sweep does not need to be short and, in fact, can be quite long. The longer the sweep the better the SNR.
# A far-field IR is not a "truer" representation. It is simply the response of the cabinet in the far field. A near field IR is equally "true", it just sounds different. Far field IRs are not a panacea either. They're difficult to obtain for speakers with multiple drivers, i.e. 2x12, 4x12 because the far field is extremely far away. At 10 kHz the far field for a 4x12 is something like 100 ft. (too lazy to do the math right now).
When we listen to multiple driver speakers we are typically in the Fresnel zone. If you take an IR of a multiple driver speaker in the Fresnel zone there will be deep notches in the spectrum due to the different path length of each driver. We don't hear this though because we have two ears and our aural processing averages things out.
</blockquote>

<blockquote>
[https://www.thegearpage.net/board/index.php?threads/my-thoughts-on-reflection-free-irs.2280348/post-33067524]
A reflection free IR will NEVER sound the same as a real cab because the directivity of a monitor is very different.
</blockquote>

<blockquote>
Even a single 12" guitar cab will sound markedly different than a RFIR because the high frequency beam pattern is markedly different. Cabs with multiple speakers exacerbate the problem.

You can capture an IR of a cabinet at one point in space but it's just that: one point in space. Good monitors are designed to have smooth beam patterns with wide dispersion. A guitar cab has poor dispersion as the frequency increases. This is what causes the infamous "beaming" of high frequencies.

This causes two things. The first is a psychoacoustic effect because the sound changes rapidly with angle and our ears are a finite distance apart. One ear hears something different than the other. The other is the interaction with the room. A monitor, with its broad dispersion will send a wide range of frequencies to the various surfaces in the room. A guitar cab will send more low frequencies to the surfaces where high frequencies will be beamed. The "reverb excitation" system function is therefore different.

As a simple example consider sitting off to the side of a guitar cab and there's a wall on that side. The lower frequencies will hit that wall and reflect back to you but the higher frequencies are beamed and don't hit that wall. Now repeat that with a monitor. By design the monitor has much greater dispersion so the high frequencies hit that wall and reflect back.

The result is that guitar cabs sound "warm" in a room environment when listening off-axis (which is nearly always).

So in theory you could capture an IR at the same distance and angle as your listening point but using that IR through an FRFR monitor will simply not sound the same because of the aforementioned reasons. It may be close enough for some people but IME it's not close enough and does not offer the same experience.

And this is just the tip of the iceberg. You also have to consider near-field vs. far-field. For a guitar cab we are typically in the near-field for the higher frequencies at typical listening distances. This exacerbates the change in sound vs. angle and the resulting psychoacoustic effect.

The irony in all of this is that great pains are taken to obtain a reflection-free IR. That IR is then used in an FRFR monitor that generates reflections and the reflections generated are very different than the reflections generated by the guitar cab. That fact alone makes the whole exercise futile.

The best way to get AITR sound from something that's not a guitar cabinet is to use something that's *almost* a guitar cabinet, like a Celestion F12-X200 and then apply EQ to morph the sound. Or just use a guitar cab and a power amp and stop trying to use a hammer when you really need a screwdriver.

</blockquote>
</blockquote>

More information:
* [http://community.plm.automation.siemens.com/t5/Testing-Knowledge-Base/Sound-Fields-Free-versus-Diffuse-Field-Near-versus-Far-Field/ta-p/387463 Siemens: Sound Fields: Free versus Diffuse Field, Near versus Far Field]
* [http://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/ Fractal Audio Far-Field Session 2 IRs]
* [https://forum.fractalaudio.com/threads/tone-versus-feel-the-real-amp-in-the-room.149643/page-3#post-1776371 AlbertA's explanes the differences between near-field and far-field]

About Fractal Audio's Far-Field Session 2 IRs:

* The pack is free. The IRs can only be used with the Axe-Fx III.
* The IRs are mostly reflection-free in the first 20 ms area. Although the IRs themselves are longer, it recommended to set IR length in the Cabinet block to 1024.
* There are "A" and "B" IRs. They indicate different distances. The number which follows is the number of degrees that the cab has been rotated away from the microphone.

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>

[http://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/post-1799269]
Some minor reflections from some immovable objects within the "zone of silence". Nothing severe.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/post-1799285]
We did the best we could given the building and circumstances. There are steel posts that support the roof that were likely the source of the minor reflections. Also the environment was a bit noisy. There's a transformer that was humming. We surrounded it with bags full of foam peanuts in an attempt to reduce the noise. Statistically they aren't perfect but when we listened to them we were quite pleased. It's not difficult to obtain a far-field IR. What is difficult is finding a good space. Since we have the building the only cost to us was our time. Since no studio costs were involved we can offer these as free. If they work for you great, if they don't, nothing lost.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/post-1799651]
The gap at the beginning is because they aren't min-phase, they are auto-trimmed. The distance from the mic to the cab would be much greater but that's automatically removed (and we manually reduce it before-hand in the IR Capture menu).
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/post-1800363]
The magnitude of the reflections is very low. Comb filtering occurs when you add two signals where one is delayed vs. the other. If the magnitude of the two signals is equal the notch depth is infinite. As the magnitude of one decreases the depth of the notch decreases. Once you get -20 dB down or so the notch is insignificant. The amplitude of the reflections in these IRs is -30 dB down. For example if you have two equal signals and one is delayed by, say, 10 ms there will be infinite notches at 50, 150, 250, ... Hz as the delayed signal will be destructively interfere with the non-delayed signal at those frequencies (x - x = 0 => -inf dB). If the amplitude of the delayed signal drops to 1/2 the depth of that notch is now only 6 dB. I.e. x - 0.5x = 0.5x => - 6 dB. If the amplitude drops to 0.1 (-20 dB) then the notch is very small: x - 0.1x = 0.9x = -0.9 dB. At -30 dB the notch depth is x - 0.03x = 0.97 => -0.26 dB. This means ~1/2 dB amplitude variation over the spectrum. Our ears can't hear that.

</blockquote>
</blockquote>

==FullRes==

Up to 64000 samples, 1.37 sec.

FullRes IRs require more CPU power than Normal and UltraRes.

Firmware 17.xx release notes:

<blockquote>
<HR>
<blockquote>
Version 17 introduces FullResTM Impulse Response processing. FullRes processes IRs up to 64K points with zero latency using a novel technique. This provides up to 1.37 seconds of response time. Seasoned producers and engineers often mix in “Room Mics” during recording to increase the depth and liveliness of recordings. However, the typical live room has a reverb time of 500-700 milliseconds, well beyond the 20-40 ms afforded by typical IR processing. FullRes allows capturing the full response of a typical live room and even the response of small-to-medium halls and clubs. FullRes can also be used for convolution reverb applications for reverb times less than 1.37 seconds.

The IR Player block and the Cabinet block both support FullRes IRs. The last two slots of the Cabinet block support FullRes. This is sufficient to provide two room mics, a left and a right, along with two direct mics within a single Cabinet block.

The new FullRes User IR bank (Axe-Fx III Mark II and Turbo only) supports up to 64 FullRes IRs. When capturing an IR selecting the USER FR bank will automatically set the IR Type to FullRes. Likewise, when setting the IR Type to FullRes the bank will automatically be set to USER FR. FullRes IRs can be processed with minimum-phase or auto- trim, if desired. However, minimum-phase is not recommended as this will tend to destroy the reflection information.

The Scratchpad bank has been updated to support FullRes IRs (Axe-Fx III Mark II and Turbo only).

The original Axe-Fx III has less non-volatile memory and therefore does not have the necessary resources to store the IRs. The Scratchpad bank supports FullRes IRs but the data will be lost when the unit is powered off.

Added 10 FullRes IRs to the Legacy bank provided by Valhallir and York Audio (Axe-Fx III Mark II and Turbo only). These are at the end of the bank. These can be loaded into the IR Player blocks or into Slots 3 and 4 of the Cabinet blocks. Note that Slots 1 and 2 of the Cabinet blocks do not support FullRes.</blockquote></blockquote>

FullRes IRs are intended to capture "room mics" and reproduce these when recording or when playing through headphones. Room mics are sometimes mixed in to increase the depth and liveliness of recordings. They allow capturing the full response of a typical live room and even the response of small-to-medium halls and clubs. [https://forum.fractalaudio.com/threads/aitr.176587/post-2145064]

The expected approach is to combine a regular short (close-mic'd) IR with two (longer) room mics for ambience. This separation allows separate control over the direct sound and the (stereo) acoustic space.</blockquote>

[https://www.fractalaudio.com/tmp/AITR_Toad.mp3 Recording example]

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/aitr.176587/post-2145657]
Normal IRs are 2K. FullRes IRs are 32 times larger so an entire bank would provide 32 FullRes slots.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-release-version-17-00-public-beta-2.176961/post-2152632]
So I came up with a solution for Mark I owners: the Scratchpad bank supports both standard and FullRes IRs. Obviously you'll lose your IR when you power off.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/aitr.176587/post-2145732]
(Axe-Fx III Mk I) It has plenty of memory for firmware updates. It has limited NV memory for user data storage because at the time it was designed the FLASH chips used were the largest capacity available. The Mark II has larger capacity FLASH chips because they're available now.
</blockquote>

<blockquote>
[https://www.thegearpage.net/board/index.php?threads/aitr-cliff-is-brewing-something-new.2287174/page-3#post-33207828]
There are two cab blocks and each block supports two FullRes IRs so you could, in theory, do stereo 2.66 seconds. We went back and forth on how much time to support. At first I was thinking 2.66 seconds but that would double the CPU use and cut the number of available IRs in half. A survey of the literature showed that the reverb time of most acoustic spaces where recordings are done is less than a second so 1.33 seemed the best balance. I plotted the IRs of a bunch of the room mic IRs I have and the reverb time was typically around 500 ms which is consistent my experience and the literature.
</blockquote>

<blockquote>
[https://www.thegearpage.net/board/index.php?threads/aitr-cliff-is-brewing-something-new.2287174/page-3#post-33207828]
The point of FullRes IRs is to add some room sound to your recordings and/or headphone playing. To do this you would mix conventional IRs with FullRes IRs.

</blockquote>
</blockquote>

FullRes IRs require more CPU power than Normal and UltraRes IRs. Also, they are relatively large and require some time to load. Therefore, gapless switching (channels, scenes, presets) is not supported when using Full-Res IRs.

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/not-yet-fixed-gap-with-amp-cab-irp-channel-changes.200360/#post-2541456]
Full-Res (room) IRs are large and take a long time to load. Gapless switching is not supported when using Full-Res IRs.
</blockquote>
</blockquote>

To support FullRes: several adjustments have been made:

* Only slots 3 and 4 of the [[Cab block]] support FullRes IRs for stereo reproduction (left+right room mics). So does the [[IR Player block]].
* Full Res IR files will not be visible unless you select them in slots 3 or 4.
* [[IR Capture]] supports capturing FullRes IRs.
* The Axe-Fx III Mk II has a dedicated user bank for FullRes IRs.
* FullRes IRs can be processed with minimum-phase or auto-trim, if desired. However, minimum-phase is not recommended as this will tend to destroy the reflection information.
* A FullRes Scratchpad is available for auditioning IRs during the capture process.
* [[Cab-Lab]] will be updated to support FullRes IR captures and management. [https://forum.fractalaudio.com/threads/aitr.176587/post-2145186]

About FullRes and Far-field IRs: not the same thing. They both capture the sound at longer distances, but where far-field IRs capture the sound coming directly from the speaker, FullRes IRs are intended for capturing the room (ambience) only. Both types of IRs are aimed at reproducing the sound of a guitar speaker as we hear it "in the room", as opposed to close-micing and recording a speaker. Where far-field IRs should have the least possible "room reflections", FullRes relies on them. [https://forum.fractalaudio.com/threads/aitr.176587/post-2146858]

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>

<blockquote>
[https://forum.fractalaudio.com/threads/aitr.176587/post-2148312]
A far-field measurement is only the response of the transducer. There's a couple ways to do far-field measurements:
# Suspend the speaker and mic in air far enough above the ground so that the ground reflection arrives after the direct signal.
# Use a ground plane measurement technique outdoors or in a space large enough that any reflections arrive after the direct signal.
A room mic is completely different and it will have the room reflections, which are desirable and give the mix "space". It will also have the response of the mic "baked in".

</blockquote>
</blockquote>

FullRes also allows the use of convolution reverbs, shorter than 1.33 seconds. [https://forum.fractalaudio.com/threads/aitr.176587/post-2145186]

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>

<blockquote>
[https://forum.fractalaudio.com/threads/aitr.176587/post-2146237]
You can ALSO use FullRes IRs to do short-to-medium convolution reverbs. If you have some reverb IRs you can convert them to FullRes IR format and load them in the IR Player block and use that as a reverb.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/aitr.176587/post-2146237]
Algorithmic reverb is considered to be superior to convolution reverb because algorithmic reverb can be perceptually tuned. From a perceptual standpoint the ideal reverb is not found in typical reverberant spaces. See the work done by Griesinger, et. al. on perceptual reverberation.

</blockquote>
</blockquote>

The factory FullRes IR in the Legacy bank are:

* 190 — 4x12 V2 Viper Room L (Val)
* 191 — 4x12 V2 Viper Room R (Val)
* 192 — 2x10 Vibrato Lux Room L (YA)
* 193 — 2x10 Vibrato Lux Room R (YA)
* 194 — 2x12 Class A 30W Room L (YA)
* 195 — 2x12 Class A 30W Room r (YA)
* 196 — 4x12 Brit Greenback Room L (YA)
* 197 — 4x12 Brit Greenback Room R (YA)
* 198 — 4x12 Recto Room L (YA)
* 199 — 4x12 Recto Room R (YA)

==DynaCab==

2048 samples.

Part of DynaCab cabinet modeling, introduced in firmware 22 and later for the Axe-Fx III (and corresponding FM3 and FM9 firmware).

Read this: [[Cab_block#DynaCabs|DynaCabs]]

=Far-field IRs and close-mixed IRs=

See above.

=Interesting IRs=

'''Commercial and free IRs'''

The processors contain a lot of factory cabs, aka stock cabs. [[Cabinet models list]]

You can also create your own IRs with [[IR Capture]] or software, acquire IRs from sources such as [http://axechange.fractalaudio.com Axe-Change], or from commercial vendors, including Fractal Audio.

Fractal Audio's free IR libraries:

* [http://www.fractalaudio.com/downloads/misc/Cab-Pack-1-Wellspring-Sound.zip Wellspring Sound (Vol. 1)]
* [https://forum.fractalaudio.com/threads/non-minimum-phase-irs.146046/ Wellspring in non-MPT format]
* [http://www.fractalaudio.com/downloads/misc/Cab-Pack-2-Mad-Oak.zip Mad Oak Studio]
* [http://www.fractalaudio.com/accurate.php IRs from a session with Larry Mitchell]
* [http://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/ Fractal Audio's Far-Field Session 2 IRs]
* [https://forum.fractalaudio.com/threads/free-irs-in-celebration-of-the-80th-birthday-of-frank-zappa.168497/#post-2024072 Free IRs in Celebration of the 80th Birthday of Frank Zappa]
* [https://forum.fractalaudio.com/threads/free-hj-4x12-rca-cab-pack.156177/ Free HJ 4x12 RCA Cab Pack]

Some commercial manufacturers provide free impulse responses. There are also quite a few popular impulse responses available in the public domain. Some examples:

* [https://axechange.fractalaudio.com/detail.php?cab=377 gtrbody] — Adds the resonant sound of an acoustic guitar body.
* cello_body — Adds the resonant sound of a cello.
* [https://axechange.fractalaudio.com/detail.php?cab=86 GuitarHack ThisOne V30]

'''Acoustic instruments'''

When recreating the sound of acoustic instruments (acoustic guitar, cello, violin etc.), an IR of an acoustic body may improve the sound. You can find some on [[Axe-Change]].

Acoustic sounds benefit from long IRs with some room ambience, so UltraRes or even FullRes IRs are preferred.

'''Flat IR'''

The Factory 2 bank has a "totally flat" IR.

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>

Allows to individually adjust Mic Distance for phase adjustment of the "DI", while still enjoying the Preamp modeling and Mix controls of the Cab block without complex routings.

The totally flat cab has no filtering and sounds absolutely wretched. It's only there for diagnostic and special effect purposes.
</blockquote>
</blockquote>

=IR Capture=

Read this: [[IR Capture]]

=Tone Matching=

Read this: [[Tone Match block]]

[[Tone Match block#Use Tone Match to capture an IR|Use Tone Match to capture an IR]]

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>

<blockquote>
[http://forum.fractalaudio.com/threads/how-about-some-micing-tips-for-tone-matching.62089/#post-771270]
The IR is vastly more important. Tone Matching is a nifty feature and certainly useful but you'll get far more satisfaction by concentrating on capturing good IRs. The single most important aspect of recording guitar amps is micing the amp. Therefore the single most important aspect of using your Axe-Fx is the IR. People are too hung up on "matching" or "profiling" an amp but fail to realize that when you are doing that you are basically capturing an IR. If you capture the IR separately now you have an IR that is fully separated from the amp and therefore can be used with all models. Matching and profiling cannot mathematically separate the amp's frequency response from the cabinet frequency response. Once you do this you'll be surprised at how accurate the amp models are. I do this all the time and find Tone Matching is unnecessary now (in fact many of the amp models have had their built-in matching data removed in the latest firmware). Any differences between the model and the real amp are so minuscule as to be immaterial. A little tweak of the tone stack or EQ is usually enough to remove and differences. Besides, once you get into mixing you'll realize that you'll be applying EQ anyways so tiny differences in EQ are irrelevant. Moving the mic just a small amount drastically changes the sound. The best producers have mastered micing. You can only fix so much via EQ since EQ is essentially painting with a broad brush where mic technique is akin to using a fine-point brush.

There is NO substitute for shooting an IR of the cab. IMO, this is the single most important thing you can do. Everything else is attempting to learn the cab IR through an indirect method and then you have inseparability. If you shoot the IR then do a Tone Match you can change the cab after or do another IR with a different mic or mic position and your matching data is still valid.

</blockquote>
</blockquote>

= Volterra kernels=

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>

[http://forum.fractalaudio.com/threads/will-we-see-improvements-new-tech-regarding-speaker-cabinets.135191/page-2#post-1599277]
The Axe-Fx III (and II) actually capture the Volterra kernels when doing an IR capture (it's hidden in the firmware for possible future use). I've studied dozens upon dozens of them and the kernels above first order (the first order kernel is the linear IR) are so small as to be inaudible. The distortion from an amp is orders of magnitude greater even when using a clean amp. The only significant nonlinear thing I've measured that speakers do is thermal compression (that we model already) and "cone cry" which sounds like sh*t. Jay Mitchell is probably the leading authority on speaker design and he has stated pretty much the same thing. I'm all for improvements but they need to be real improvements. I've sat here countless times comparing an IR to the actual speaker with a mic on it doing blind A/B tests and can NEVER tell the difference and I think my ears are pretty good. I dug through my Matlab stuff and found this. (graph) This is an IR of a speaker taken twice. The first time the drive level is around 1W (in red). The second time the amp was turned way up, I would estimate at least 50W (in blue). As you can see the difference is extremely small. There's a small difference from 10 Hz and down which is way below the reproduction range of any system and a difference way up at Nyquist (24 kHz) but that's 100 dB down (!). Furthermore we don't know if the tiny differences are from the speaker or from the amp or the mic or the mic preamp. I should add that speakers can and do distort (when Xmax is exceeded) but it's not a pleasant sound. Since the displacement of the cone is the inverse of the frequency the low frequencies are distorted which is the opposite of what you want when creating "pleasing distortion". Speaker distortion is flubby, flabby and farty. The Axe-Fx II and III can simulate that, if desired, using the Speaker Drive parameter in the Amp block. I always set it to zero. There are probably some other modes that cause distortion but, again, these are dwarfed by the distortion of the amp. The only other significant one I've experienced is cone cry. Manufacturers go to great lengths to prevent it from happening. I have a speaker here that does it. Whenever I play a high F it cries and it's annoying.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/anyone-try-using-ua-ox-stomp-for-their-cabs.198601/post-2470708]
If you want "nonlinear IRs" you need to use something like Volterra kernels. I've experimented with this and, in fact, the Speaker Drive and Speaker Thump parameters essentially create higher order Volterra kernels based on various amp parameters. The harsh reality is that speakers are pretty darn linear. Things like cone cry are design/manufacturing defects and shouldn't be modeled IMO. There is some low frequency distortion and we model that but a classic, linear IR is the gold standard for replicating the sound of a speaker. Armchair pundits like to pontificate about "IRs are the weak link, blah, blah" but they're typical internet loudmouths who have little to no expertise and would fail a double-blind test every time. Now, thermal compression is definitely a factor and we model that quite extensively. As you play the voice coil heats up and its resistance increases. The radiation resistance does NOT change, however, so the resulting acoustic output decreases. There's a lot more involved when simulating a tube amp though and I can't disclose that stuff because it's proprietary. Another factor is the actual speaker impedance. It's a function of displacement. Again, we model this extensively. As the speaker moves in/out of the magnet the Bl product changes and therefore the inductance and various other electrical parameters change.

</blockquote>
</blockquote>

=Videos=

[[video:Wampler-IR]]
[[video:AdamSteel-IR]]
[[video:Sonic-IR]]
[[video:PeteThorn-CelestionIRs]]
[[video:Dolce-AcGuitar]]

[[category:Axe-Fx2]]
[[category:Axe-Fx3]]
[[category:FM3]]
[[category:FM9]]
[[category:AX8]]
[[category:Sounds]]
[[category:All]]

Impulse responses (IR)

2025-04-09T08:43:27Z

Komdosh: /* HiRes */ samples should be a power of 2. So it is 2048, not 2040

__TOC__

=About Impulse Responses (IRs)=

To recreate the tonal characteristics of (mainly) speaker cabs, the [[Cab block]] and [[IR Player block]] rely on impulse responses (IRs).

An impulse response or IR is a collection of data that represents sound measurements taken from a speaker cabinet or system. A test signal is played through the actual speaker, recorded, and used to generate a profile which is stored as a file. The profile (IR) can then be used by an IR loader, such as the Cab block, and IR Player block (Axe-Fx only), to produce the sound of the speaker.

The terms "cab", "user cab" and "IR" are synonyms.

The Axe-Fx II also used IRs to reproduce the characteristics of specific microphones. This feature has been dropped in later firmware.

Most speaker IRs reproduce the tone of a speaker that was recorded with the microphone close to the speaker, aka "near-field" or "close-miked". [[I/O_connectivity_and_levels#Close-miking|More information.]] "Far-field" IRs represent the sound of a speaker that was captured at a long(er) distance. These IRs represent (to a certain extent) the "in-the-room" sound of a traditional guitar speaker, see below.

[http://en.wikipedia.org/wiki/Impulse_response Wikipedia: impulse response]

From the [[Owners Manuals]]:

<blockquote><HR>
<blockquote>
Fractal Audio Systems speaker simulation technology is incredibly accurate, yet some listeners find the sound of IRs unfamiliar at first. This is because impulse responses typically recreate the sound of “close miking.” When you mic a guitar speaker, the mic “hears” something very different to what you might hear. Our ears are by definition “neutral” whereas a mic has distinct “color.” We typically listen at a distance (and speaker tone is very different as we move around) while a mic is inches away and stationary, focusing on the desirable sound at a specific spot.
As guitarists, we are accustomed to the sound of a speaker “in the room,” but this is not what our audiences hear. For recording and performing, the close mic’d sound is essentially a universal standard. THIS is the sound that the Cab block is designed to reproduce, and this explains why not only guitarists, but recording and front-of-house engineers have embraced its use. (Of course our Amp models can also be used with a traditional guitar speaker as demonstrated in many of the rig designs in Section 1: Setting Up).
If you are new to using mics on a guitar amp, you will find the Cab block is a fantastic way to learn more. To get started, listen to single IRs, or explore the factory presets which combine several at once. For almost a century, artists, producers and engineers have honed the craft of placing or blending mics to achieve a desired tone. Many classic techniques are easy to recreate. Try a tried-and-true “recipe” blending one “bottomy” and one “bright” mic, or try something totally original.
The factory content includes dozens of speakers with multiple different mics in different positions. You may also enjoy “Mix” IRs by Fractal Audio or 3rd-parties, which bring a producer’s experience to you in a single IR. In any case, recognize that the sound of IRs is the very sound of the speakers and mics they capture.
</blockquote>
</blockquote>

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>

<blockquote>
An IR stands for "Impulse Response". In mathematical terms it is the time response of a system to a Dirac delta function (also known as an impulse). An IR can be used directly as the coefficients for an FIR (Finite Impulse Response) filter. In the modeling world IRs are obtained from real speakers and when processed using an FIR filter produce extremely accurate results. In essence an IR is a "sample" of the speaker and microphone and uses very similar principles. However the quality of any IR is subject to the talents of the individual(s) capturing the IR. Mic placement, preamp choice, etc., etc. are important as you are essentially recording the speaker. In the old days modelers used EQ to emulate speaker response but I don't think there are many left that still use that technique. So the quality of the IR is really the issue here. The original Axe-Fx pioneered this technology which has since become almost ubiquitous.
</blockquote>

<blockquote>
[https://www.thegearpage.net/board/index.php?threads/has-anyone-cracked-open-an-ir-to-see-what-all-its-really-doing.2037093/#post-28343491]
It's analogous to a sampler. Consider the sample of, say, a kick drum. You make a short recording of that and then "trigger" that recording. If you want the kick drum louder you make the trigger louder. Now assume you trigger that recording thousands of times a second at varying amplitudes. That's essentially how IRs and convolution work. You trigger the recording at the sample rate and each playback is weighted by the sample amplitude.
</blockquote>

<blockquote>
[https://www.thegearpage.net/board/index.php?threads/jason-sadites-video-claiming-proving-that-an-ir-is-nothing-but-just-a-static-eq-curve.2256176/post-32574997]
An IR is the coefficients for a Finite Impulse Response (FIR) filter. A classic EQ is an Infinite Impulse Response (IIR) filter. FIR and IIR are both filters which we call "equalization" in the audio realm. You can design an FIR using various techniques. These techniques yield the coefficients for the filter. Another way to obtain the coefficients is to "sample" them from a linear system. You can approximate an FIR filter with an IIR filter. There are techniques for creating a cascade of second-order sections (SOS) from an FIR filter (Prony's method is one).
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/why-do-some-irs-and-dynacabs-seem-to-compress-more-than-others.202405/page-2#post-2532466]
EQ curve" is semantics. It's a filter. In this case usually an Infinite Impulse Response (IIR) filter. There are two types of filters: Infinite Impulse Response (IIR) and Finite Impulse Response (FIR). An "IR" as we use the term is an FIR. It's a filter and, hence, could be said to be an "EQ curve".

The name "filter" arose because it filters out certain frequencies and lets others pass. Both an IIR and FIR accomplish this. The difference is that an FIR has no poles, only zeros. An IIR can have both poles and zeros. An IIR can achieve similar performance to an FIR with a lower order thus making it more efficient to implement. IIRs, however, typically have nonlinear phase response whereas an FIR can be linear phase.

</blockquote>
</blockquote>

=IR properties=

==File formats==

Capturing IRs creates WAVE files (.wav). WAVE files can be converted into SYX (MIDI System Exclusive) files using [[Cab-Lab]] or the Fractal Audio's current editors. When using Cab-Lab to convert WAV files, and when using IR Capture to create IRs, two files are created: an IR file (.ir) and a SYX file (.syx). The .IR file is raw IR data which can be imported into Cab-Lab for mixing purposes. Cab-Lab is the only application that can handle .IR files.

==Sample rate==

Impulse responses are tied to the sample rate of the processor. Fractal Audio's modelers are set to a fixed sample rate of 48kHz.

Read this: [[Digital_I/O_and_audio#Sample_rate_is_fixed_at_48kHz|Sample rate]].

==Auto Trim==

This removes superfluous leading silence from the start of the IR. Many commercial IRs do not require this. It might come in handy when shooting your own IRs using [[IR Capture]].

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/what-to-do-when-you-can’t-line-up-irs.146531/post-1733402]
There is no wrong place to trim. It's impossible to know where the data starts because of noise. So we find where the data starts to increase, back up a few samples and trim there.
</blockquote>
</blockquote>

==Minimum Phase Transformation (MPT)==

This verifies that the phase of the IR causes no issues when mixed with other (MPT) IRs, by time-aligning the IR. This is especially important when you mix multiple IRs and you don't want to align them manually in Cab-Lab, in the DAW or on the Axe-Fx III hardware. All legacy factory cabs are MPT (Minimum Phase Transformed) to make them mix-compatible. When neither Min Phase or Trim has been applied, the impulse response is considered "raw", containing the original phase details.

[[Cab-Lab]] and the editors let you apply MPT or Auto Trim when importing files, manually or automatically.

Current firmware lets you align multiple IRs in the Cab block manually. Read this: [[Cab_block#Align|Cab block: Align]]

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>

<blockquote>
[http://forum.fractalaudio.com/threads/minimum-phase-how-does-it-affect-the-sound-of-an-ir.141597/#post-1684780]
If it's a cab IR the difference is basically nil because a speaker is a minimum-phase device. All minimum-phase does in this case is automatically remove the leading silence. A room IR is not minimum phase so you should not use MPT when processing a room IR.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/phase-problem-with-imported-oh-cabs.144009/#post-1704419]
The factory cabs are minimum phase for precisely the reason that mixing non-minimum phase leads to phase problems.
</blockquote>

<blockquote>
All the factory cabs are minimum-phase transformed so they are, by definition, "in phase" with each other.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/non-minimum-phase-irs.146046/]
So I've been doing a lot of critical listening the last couple months and have come to the conclusion I like non-minimum phase IRs better. The difference is subtle. They don't really sound that different but there are differences in the attack and in the feel. They just sound/feel a little more open and realistic. Another thing is that they mix very differently. It's less predictable but more natural. The caveat is that it's like mixing real mics, you need to experiment moving each mic in and out whereas with minimum phase you can usually just leave one mic at zero and move the other in and out. So here's a [http://www.fractalaudio.com/downloads/firmware-presets/axe-fx-3/Wellspring_NonMP.zip zip file] of my favorite IR session, the Wellspring session, in non-min phase format for use with the Axe-Fx III. My suggestion is to put them in one of the user banks and compare with the factory min-phase versions. Note that names are a bit different but you should be able to figure it out.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/non-minimum-phase-irs.146046/page-2#post-1727265]
Minimum vs. non-minimum phase changes the "delay" of the individual frequency components of the waveform. In a minimum phase system the individual sine waves have the least phase possible which concentrates the energy near the start of the waveform. For example consider a sine wave with an isosceles triangle envelope. The energy is concentrated at the center of the waveform (at the apex). The Fourier transform of that is mostly the primary frequency with a bunch of other sine waves at various amplitudes added. We can phase shift the component sine waves and the magnitude (frequency response) will not change but the waveform will. If we make it minimum phase the sine waves will add up so that the energy is concentrated at the beginning of the waveform and the waveform will then look something like a sine wave with a right triangle (ramp down) envelope.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/ir-length.155295/post-1848242]
I've long maintained that a guitar speaker is essentially a minimum-phase device and that the benefits of MPT'ing the data far outweigh any minuscule differences in the IR phase response (the magnitude response is identical).
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/ir-length.155295/post-1848701]
Raw is technically "better" but the difference between raw and MPT is minimal. The disadvantage of raw is that you have to manually align them if you are mixing IRs.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/aitr.176587/post-2145066]
FullRes IRs can be processed with minimum-phase or auto-trim, if desired. However, minimum-phase is not recommended as this will tend to destroy the reflection information.

</blockquote>
</blockquote>

DynaCabs are always time-aligned (but not minimum phase) without destroying phase information, allowing them to be mix-and-matched. You can mix-and-match IRs from different cabs/mics and they'll always be perfectly aligned. They have 0.3 ms of leading silence.

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/fm9-latency-around-5ms.200203/page-5#post-2498733]
It's because they are not minimum-phase transformed.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-22-00-public-beta-beta-6.193187/post-2402312]
The files are initially aligned to the same reference point -- a universal standard across all DynaCapture IRs. In other words, IRs for mics that are farther away have been time compensated to be aligned with IRs for mics that are closer. You can use the controls on the Align page in the usual way, however, to add time to any individual IR.
</blockquote>
</blockquote>

=IR resolution=

Fractal Audio's amp modelers and software support impulse responses of various lengths. This is also referred to as: resolution. This is measured in samples or milliseconds. The number of (milli)seconds of an IR is calculated by dividing the length (in samples, aka points) by the sample rate. All Fractal Audio devices are set to a fixed sample rate of 48000 Hz. Read this: [[Digital_I/O_and_audio#Sample_rate_is_fixed_at_48kHz|Sample rate]].

The Axe-Fx III, FM9 and FM3 let you edit the length of a legacy IR in the [[Cab block]] (hardware and editor). This affects CPU usage (longer = more CPU usage). The Axe-Fx III also lets you do this to DynaCabs (FM3/FM9: n/a).

==Normal (Standard)==

The number of samples is 1024 samples (1K), 20 ms.

However, the Axe-Fx III refers to 2K IRs (40 ms) as Normal IRs.

1024 samples suffice to capture the essential sound of the speaker cabinet, without so-called room reflections. In general, you can use Normal Res without having to worry that the sounds is not as good as HiRes or UltraRes. "Normal" is also referred to as: "Standard".

1K is the default IR length in the FM3 and FM9.

<blockquote>
'''FRACTAL AUDIO QUOTES'''
<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/red-wirez-cab-impulses.20808/page-12#post-350947]
99% of the information in a cabinet impulse response is in the first few ms. 1024 samples is more than enough to capture the essence of the cabinet and much of the room mics. You don't need a DAW, simply send the sysex files to your Axe-Fx.
</blockquote></blockquote>

==HiRes==

2048 samples, 40 ms.

Double the length of the "normal" IR, allowing it to store more information after the first 20 ms. HiRes IRs use more CPU than Normal Res, and also more than UltraRes. Because of this, HiRes as a label / format was discontinued, although the Axe-Fx III still supports it (the Axe-Fx III refers to 2K IRs (40 ms) as Normal / Standard IRs).

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/axe-fx-ii-technical-questions-thread.35997/page-45#post-495810]
There are a couple reasons for 2048. Probably most important is that it allows 1024 in stereo mode. To be able to do stereo 1024 requires a 2048 convolution engine. Secondly, some IRs benefit from longer IRs. Better to have the ability and not need it than the converse.
</blockquote>
</blockquote>

==UltraRes==

Up to 8000 samples, 170 ms.

UltraRes speaker IR processing is a Fractal Audio proprietary technique which enhances the spectral resolution of an IR without adding CPU burden or storage requirements. UltraRes IRs allow more information to be captured than Normal or HiRes IRs, especially in the lower frequencies. UltraRes IRs require more CPU power than Normal Res but less than HiRes. UltraRes lRs are displayed in italics or in a different color in the software editors.

About UltraRes IRs:

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>

<blockquote>
The problem with conventional IRs is that they are too short to capture the detail in the low frequencies. There are those that maintain 20 ms is the maximum length you need to fully replicate the speaker. This would be about 1000 samples at 48 kHz. I disagree with this as I have many IRs here that exhibit significant energy beyond 20 ms. I believe the room has some influence as the low-frequency modes of the room will impact the resulting sound. The amount of this impact depends on the room, the mics, distance, etc., etc. Or perhaps certain speakers have particularly high Qs in the low frequencies. Regardless, it is my opinion that you need IRs much longer than 20 ms to fully capture the "mic'd amp in the studio" sound. My tests show that IRs of 8000 samples are required to fully capture the low-frequency detail. Unfortunately to process an 8K IR in real-time require copious processing power... Fortunately I have developed "Ultra-Res" cabinet modeling. Ultra-Res cabinet modeling provides the frequency detail of a very long IR with little or no added processing power requirements.

Existing IRs will still be processed as usual. Ultra-Res IRs will be tagged as such which will indicate to the processor to use the new processing algorithms. Note that Ultra-Res IR data is not conventional IR data.

The frequency resolution of an IR is the sample rate divided by the number of samples in the IR. The window function has nothing to do with frequency resolution (except for making it even less). So a 1K IR at 48 kHz sample rate has a frequency resolution of roughly 48 Hz. If a speaker has a resonance (formant) at, say 80 Hz with a Q of, say, 3.0, then 48 Hz is insufficient to capture that resonance accurately. You need a frequency resolution of several Hz to accurately recreate that resonance. I chose 80 Hz and a Q of 3 because that's what that response looks like. The Q could even be higher than that. It doesn't take much mental energy to realize that if you have a narrow formant at a low frequency then you need fine frequency resolution to reproduce that. An 80 Hz formant with a Q of 3 only spans about 25 Hz. Obviously a frequency resolution of 48 Hz is not going to be able to reproduce that. Windowing only smooths the response even more. This is basic FFT theory. The less time-domain information you have, the less frequency domain information you have and vice-versa. This is the uncertainty principle. I always window IRs with a Hann window.

Another way to look at it is to think in terms of formants. That particular speaker has a pronounced 80 Hz formant. It takes well over 100 ms for the energy of that formant to decay to the point of imperceptibility. Obviously a 20 ms IR can't reproduce an event that occurs for over 100 ms. Here is a zoom of the original non-minimum-phase IR (IOW raw time response)... (see thread for image). You can clearly see the 80 Hz formant. There are some room reflections but they are very small. The 80 Hz formant starts well before any reflections. It's obviously a high-Q resonance as it rings for quite a while. The higher the Q, the longer it takes to decay.

Here's another example. (see thread for image) This is one of the new OwnHammer IRs. The IR is OwnHammer_412_MAR-CB_D-120_SS_RBN-121. These IRs are 100 ms long (4800 samples). I windowed the original IR to 4K to prove a point. The blue trace is the original IR (windowed to 4K samples). The green trace is the "typical" 20 ms IR (windowed to 1K samples). The red trace is the Ultra-Res version.

The problem is that human perception is logarithmic and IRs are a linear process. 48 Hz resolution is way more than necessary at, say, a few kHz but not nearly enough at low frequencies. The brute force solution is to use very long IRs, 8K or more. Ultra-Res solves this in a novel way that uses little to no extra processing power and no additional latency.

Normalization is your friend. Rectangular windows are simply truncation and are generally regarded as bad practice due to extremely high sidelobe levels. The choice of window is subjective. I actually use my own custom window that is not really a Hann window but that's proprietary information. My window preserves more frequency detail while still suppressing Gibbs phenomenon. Windowing trades off frequency resolution for sidelobe suppression. My window is optimized for the unique statistics of IRs. For a random process I tend towards Bessel-Kaiser windows. IRs have unique statistics that aren't addressed by any of the standard textbook windows.

Let me state these points:
# We don't record guitar amps in airplane hangers or anechoic chambers. We record them in studios.
# When we record a guitar amp we carefully set the amp up in the studio to get the best sound "on tape". This involves moving the amp around, placing gobos, etc. When we collected the Producer's Packs IRs we spent hours arranging the amps/speakers, mics and gobos and playing through the amp and readjusting until we were satisfied. This also included adjusting the preamps and mixing board. In one studio we found that we got the best tone raising the cabs off the floor by a couple feet, orienting them towards a particular wall and placing gobos behind (this was the engineer's standard recording arrangement).
# At this point our objective of the IR is to capture the sound of that amp/speaker at that position in the room, with the gobos, mics, preamps, etc., etc. The goal is not to capture the raw sound of the amp/speaker in an airplane hanger or outside using a ground-plane measurement and measurement mics. That might be someone else's goal but it is not ours. IOW our goal is to treat the cab, mics, preamps, room, etc. as a whole, as a good engineer/producer would.
# Subsequent analysis of the data shows that there is significant energy out to 100ms and even beyond. However there is little energy beyond 200 ms or so (as it should be in a well-designed studio). This observation was the catalyst for the Ultra-Res algorithm. There are other observations about the statistics of the data that I cannot disclose.
# Some cabinets displayed noticeable resonances at low frequencies. Others did not. The frequency of these resonances were not consistent and, not coincidentally, matched the measured resonance of the impedance sweep. It is a logical conclusion, therefore, that the resonance was NOT caused by the room but by the speaker/cabinet combination. Furthermore a plot of the group delay for the raw data showed that the delay of the resonance was too short to be a room mode. Regardless, whether the resonance is from the speaker or room or mics or preamps is irrelevant. All we care about is recreating the sound of that speaker as it would be recorded as accurately as possible.
# Truncating an IR destroys information by definition. We don't care where the information comes from, be it the speaker or the room or the mics or the preamps. We want all the information. If a plot of the frequency response of a truncated IR differs considerably from the non-truncated version then we have lost information and concomitant accuracy.
# NO ONE producing commercial IRs records them in an airplane hanger, for obvious reasons. The best ones are done in a studio using the same technique we used for the Producer's Packs: setting up the cab, adjusting the position, mics, preamps, etc. and playing through the amp/cab and readjusting until the best tone is achieved. The new OwnHammer IRs are an example of this. Many, if not all, of those IRs exhibit significant energy to 100 ms (and likely beyond but the data stops at 100 ms). Truncating them to 20 ms destroys vital information. You can argue the semantics all day long. I've compared truncated and non-truncated and the difference is clearly audible. It is especially noticeable when chugging power chords. You can hear the resonance. It goes "bonggggggg" as opposed to "thuk". Most importantly it sounds "better" IMO.
# Ultra-Res is an algorithm that markedly increases accuracy. It gives the frequency resolution of a 200ms IR without additional processing overhead and no added latency.

Ultra-Res is especially powerful in Tone Matching applications, particularly real-time matches and was another impetus behind the development.

The myopic only see the IR as a capture of the speaker's "unadulterated" response. As I stated before I believe the future is treating IRs as capturing the entire recording chain including mics, preamps, etc. and have pushing in that direction. We have already seen the fruits of this labor in the Producer Pack and OwnHammer V2 IRs. We used mainly PP and OH IRs at Axe-Fest this weekend and the results were stellar. Andy Wood's tone was among the best guitar tones I've ever heard live and we dialed it up in 10 minutes under far less than ideal conditions. It consisted of the Two Rock amp model and the EV 12L Mix IR. When you include more than the speaker response in the IR you can have low-frequency resonances that persist for tens of milliseconds or more. Truncating an IR destroys this LF information. In many cases this LF information loss would probably not be perceptible. In other cases, from experience, it can be extremely noticeable. The bottom line is that you can always remove the information if you don't want it but you can't add back what isn't there.

Let me phrase this another way. An IR can consist of the "raw" speaker response plus none, one, some or all of the following: mic, preamp, room, power amp (e.g. you want to capture the response of a tube amp driving the speaker), etc. If you only care about the raw response then a short IR is all that is required. However if you want any of the other elements as part of the IR then a longer IR may be necessary. Ultra-Res gives you the OPTION of processing longer IRs.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/firmware-13-beta-feedback.80939/page-2#post-983190]
If the .wav is only 40ms long there is no sense in converting to Ultra-Res as you won't gain anything. Over 80 ms is desirable. The maximum length supported is 170 ms or so. Anything longer than that is truncated to 170 ms.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/can-current-cab-lab-process-ultrares-irs.81388/post-989024]
To get the optimum results the length should be 170 ms or more. As the length gets shorter you'll lose information. However there may not be any information to lose. It all depends on the IR. I've seen long IRs where only the first 100 ms or so is actual information and the rest is silence. OTOH I've seen 100 ms IRs where there is obviously more information but it got truncated. You lose nothing with Ultra-Res except the ability to change the size of the cabinet. You gain better sound and less CPU." "You can't mix Ultra-Res IRs as the data is not compatible. However... we foresaw that and the UltraRes conversion process produces two files: a .ir file and a .syx file. The .ir file is the raw IR data that can be imported into CabLab for mixing purposes. So CabLab can take .wav, non-Ultra-Res .syx and .ir files as input to the mixer section and product Ultra-Res .syx files." "The .ir files are included with our cabinet packs. We will not be offering .wav files. If you have the .wav file you don't need the .ir file. A .ir file can ONLY be used with CabLab. If you use the Axe-Fx II to capture IRs it will only generate .ir and/or .syx files. No .wav files are generated. The resulting data can only be used on Fractal Audio products.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/nothing-beats-the-tv-mix-cabs-not-even-ultrares-opinion.84551/page-3#post-1027747]
It depends on the IR. Ultra-Res improves low-frequency resolution. It is very apparent with some IRs and virtually inaudible with others. It all depends on the low-frequency formants in the original IR. If there are significant, high-Q formants Ultra-Res will preserve those whereas conventional, short IRs will not. Audibility also varies with the amp being used. The difference is more audible with high gain as this will excite the formants more. Low-frequency formants vary with the type of cabinet and speaker. Some cabinets have a smooth low frequency response. Others have prominent formants. The mic also has an impact. Some mics will accentuate the formants. The room also contributes if it has strong LF modes. Furthermore some people like to capture an IR using a tube power amp. In this case you WILL get a significant formant at the low-frequency resonance of the speaker. A conventional IR will not capture that as the Q of the formant will exceed the resolution of the IR. Ultra-Res will capture that formant as Ultra-Res has 8 times the low-frequency resolution. Those who claim they can't hear a difference are correct. They can't. It's nothing to be ashamed of. But because they can't doesn't mean others also cannot. I can clearly hear the difference but I've trained myself on what to listen for. I vastly prefer Ultra-Res and only use Ultra-Res IRs in my personal patches (aside from the TV Mix, which is just a magical IR).
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/the-difference-between-170ms-and-500ms-ir-lenghth.126770/#post-1508992]
The length of the sweep only determines the signal-to-noise ratio. If the room is completely silent the sweep can be infinitely short (an impulse). To overcome ambient noise you need more energy in the applied stimulus. With an impulse you can only increase the power so much before the amplifier or the speaker or the mic or the preamp, etc. distort. However, if you spread that power out over a longer period of time you can increase the energy and therefore increase the SNR. Think of it this way: a 1 ms pulse at 1000W has the same energy as a 1 second pulse at 1W. Now you can't just put a 1 second pulse into a system because the pulse has little frequency content. A 1 second sweep over the band of interest allows the transfer function (IR) of the system to be obtained via deconvolution. There are other signals you can use like pseudo-noise and MLS sequences but a "chirp" has the best characteristics. In the early days of room IR capturing they used impulses generated by popping a ballon, firing a starting pistol or clapping two boards together. The results were poor due to low SNR. This lead to the development of signals that have higher energy. To get the IR of a room long sweeps are typically used because there is a lot of ambient noise and the "returned signal" is weak (the reverb portion of the response is very low compared to the direct signal). When close mic'ing a speaker the ambient noise is low and the signal strength is very high so a short sweep is adequate. In fact you could probably get away with 100 ms or less in a studio environment.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/the-difference-between-170ms-and-500ms-ir-lenghth.126770/#post-1509021]
I've never seen a cabinet IR (and I've examined thousands) that has any significant content beyond 150 ms or so. Most cab IRs are under 40 ms. The exception to this would be a "room IR" where the mic is very far from the speaker and the room is significantly reverberant. But one wouldn't normally use that as the primary tone, instead to add a little ambience to the tone and the loss of information would be imperceptible in context. Modeling products typically use IR lengths of 1K samples as this covers 90% of IRs ever captured. We support 2K and Ultra-Res (which is equivalent to 8K) which covers 99% of IRs. The amount of CPU power required to process an IR is proportional to the length of the IR. To support a 500 ms IR (24,000 samples) would require over ten times the CPU power of a 2K sample IR. It also requires over ten times the memory for storage. Given that that vast majority of IRs do not have any information beyond 40 ms it is wasteful of CPU and memory resources to support IRs longer than 2K.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/why-are-fas-irs-truncated-to-170ms.127313/#post-1514597]
The length of time you hold a chord is irrelevant. The impulse response of a speaker cab is typically much less than 100 ms. Only when there is significant room reflections is the length greater. Then you get into the whole argument of whether the IR should contain any room information.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/firmware-13-beta-feedback.80939/page-2#post-983217]
(Tone Matching and Ultra-Res) In Realtime mode the raw internal IR length is 8K which you can dump.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/firmware-13-beta-feedback.80939/page-2#post-983211]
You can export the Tone Match to CabLab and create and Ultra-Res IR.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/why-i-wont-be-using-the-cab-block-for-recording-any-more.98578/page-5#post-1182690]
I'm a huge advocate of longer IRs. In fact I think I was the first to advocate it despite all the naysayers. I pushed OwnHammer (and others) to increase their IR lengths and they were the only ones who acted on that advice (so far, maybe the other guys will start to follow suit). Ultra-Res was born out of the desire for longer IRs.

For recording you don't need to use the cab block in the Axe-Fx though. Record the raw amp sound and then "re-cab" it later. This way you can try different cabs. Cab-Lab is great for this. Cab-Lab does not do UltraRes processing. It creates UltraRes files for the Axe-Fx but it does all processing at the full IR length up to 8K samples. You can use other convolution plug-ins as well.

The reason for UltraRes is that long IRs have several drawbacks:
# They require lots of storage space. Not an issue on a computer but on a hardware product that means expensive non-volatile memory.
# They require lots of processing power if you don't want any latency. On a computer it doesn't matter since latency is a non-factor if you are processing prerecorded tracks. On a hardware product we must have zero latency.

So UltraRes was devised as a way to exploit the statistics of the data to give the benefits of longer IRs without the usual hardware drawbacks.

In my tests I've found that 8K samples (170 ms) is more than enough. I think 500 ms (24K samples) is overkill and if an IR has significant energy out that far then it has too much room in it. The speaker and cab itself are never more than 100 ms, usually much less. Anything beyond that is the room. I personally don't like IRs with lots of room in them. A little bit of early reflections are nice and make things sound less direct but too much room makes the sound get lost in the mix.

There's no meaningful data beyond 150 ms and if there is, it's the room and you don't want that much room.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/axe-fx-ii-quantum-2-00-public-beta-deux.109702/page-19#post-1314753]
(Ultra-Res 2.0) No big deal, just some improved processing algorithms. The UltraRes cabs in Quantum 2.0 were all reprocessed with UltraRes.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/cab-lab-3-3-0-released.112286/]
UltraRes 2.0 is the next level of evolution for our patent-pending speaker simulation technology, with even greater accuracy than the original version. UltraRes 2.0 cab files are backwards compatible with previous Axe-Fx and AX8 firmwares supporting UltraRes 1.0.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/low-cut-high-cut.119906/page-4#post-1426474]
"1" from the speaker is the near field. The response of a speaker in the near field is very different than the response in the far field. In the near field the response changes (drastically) across the face of the transducer. Even moving the mic a fraction of an inch will result in a very different sound. 10 ft. from the speaker is the far field and the response changes smoothly as you move across the field. If the near field were the same as the far field then the sound wouldn't change as you moved the microphone and you could place the microphone anywhere on the face of the speaker. Anyone who has mic'd a speaker knows that this isn't the case.
</blockquote>

<blockquote>
[http://www.thegearpage.net/board/index.php?threads/impulse-response-quality-no-difference-between-200-500-low-high-etc.2015600/#post-27950543]
The energy of the speaker itself is contained in less than 50 ms. Anything beyond that is room reflections. Therefore any differences that you may hear are room reflections. The question then becomes do you want room reflections. Some say yes, some say no. One approach is absolutely no room reflections and then you add them with room simulation. The other approach is to use longer IRs with reflections in them. Both are valid approaches. Close mic'ing minimizes room reflections as the direct path is much shorter than the reflections path and sound pressure decreases by the square of the distance.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-version-5-08.150760/page-4#post-1793546]
The length doesn't determine the amount of bass. It determines the resolution. If there is a sharp resonance in the bass response a short IR will smear that resonance causing it to be wider than it actually is.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-version-5-08.150760/page-2#post-1793085]
It's complicated. Some people claim you don't need any more than 20 ms. For many cabs this is true. It depends on the "formants". A guitar speaker is approximately "constant Q" and minimum phase. The peaks and dips are caused by formants and the Q of those formants is roughly constant. This means low frequencies take much longer to decay than high frequencies. I've measured some cabs with a low frequency formant that takes much longer than 20 ms to fully decay. This is the whole reason for Ultra-Res. There are no absolutes. Many cabs can be captured just fine with 10-20 ms. Others need more. If you want some of the room in there then you need more.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/ir-length.155295/post-1848227]
I've been experimenting with IR length lately and keep finding that I like a shorter length. So I gave some thought to it and I think the reason is that a shorter IR trims off the early reflections. A 1024 sample IR is over 20 ms. If there is a wall 5 ft. away that puts a reflection smack dab in the middle of the IR. The Redwirez IRs you can see (and hear) the ceiling reflection pretty clearly (ceiling was probably about 8 ft). Using a shorter IR removes that reflection. I've actually been turning down the IR length lately on my personal patches, typically 512 samples, as I find it makes the IR "clearer". While the push in the industry has been towards longer and longer IRs I'm not sure that's a good thing unless you are careful with your IR capture to ensure that you aren't capturing reflections. Some IRs, particularly ported bass speakers, may need the longer length to capture the low end with sufficient detail but the average guitar cab is probably fine at 512 or even less samples. Heck, prior to the original Axe-Fx some products were even using 128 samples.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/ir-length.155295/post-1848298]
SOMETIMES shorter is better. It depends on the environment they were captured in.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/ultrares-irs.158416/post-1893051]
FWIW, I almost always reduce IR length on my personal presets. Usually 512 or 1024. I like the lack of reflections.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/ir-length.155295/post-1849075]
The takeaways from this are simple:
# Minimize reflections as much as possible when capturing IRs. Shoot them in the largest room you can find. Elevate the speaker off the floor or angle it back to minimize the floor reflection. Make sure there is ample distance behind an open-back cabinet.
# For existing IRs that may have prominent room reflections try different IR lengths to trim out the reflections.

</blockquote>
</blockquote>

About Far-field IRs:

"Far-field" IRs represent the sound of a speaker that was captured at a long(er) distance. These IRs represent (to a certain extent) the "in-the-room" sound of a traditional guitar speaker. There are a couple of far-field IRs among the legacy stock cabs, created by Jay Mitchell ("JM"). Also, Fractal Audio has released far-field IR libraries ("Far-Field Sessions").

"FullRes" IRs also capture longer distances, but these are intended to capture the room, where "far-field" IRs are aimed at capturing the sound coming directly from the speaker at a longer distance. More about FullRes below.

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>

<blockquote>
[https://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/post-1799610]
Far-field IRs are not the panacea some are making them out to be. Some things need clarification:
# A far-field IR will still not sound exactly like "amp in the room". The reason for this is that the dispersion of a guitar cabinet is very different than that of a FRFR speaker. An FRFR speaker has far wider dispersion at high frequencies, by design. With a guitar cabinet the low frequencies are less directional than the highs. This causes the cab to interact with the room differently. So even if you capture a far-field IR it will not sound the same through a FRFR speaker.
# Most of the time we are not in the far-field of a guitar cabinet. At 10 kHz the far-field of a 12" speaker is about 18 ft. So usually we're in the far-field at some frequencies but in the Fresnel zone at others. At a typical distance of, say, 5 ft. we are only in the far-field at frequencies below roughly 3 kHz. Above that we are in the Fresnel zone.
# Because of #2 the sound at each ear can be quite a bit different. That six inches or so between our ears makes a big difference. When using a far-field IR the same sound will be presented to each ear. Even when in the far-field the sound changes pretty dramatically vs. angle because the dispersion is a function of frequency. One ear will hear more highs than the other.
# A cab with more than one speaker creates significant challenges. For example, a 4x12 has a far-field at 10 kHz that's roughly 100 feet! If you capture an IR of that cab at, say, 10 feet you are nowhere near the far-field. At anything other than nadir (aka boresight, 0 degrees) the individual speakers will contribute with different times of arrival. This results in extremely phasey sound (we were able to get some 4x12 IRs by using a special trick but in general you need to be very far away).
# We don't hear this phasiness when listening to the real cab though because of #2. We get very different signals at each ear and our brain processes these. When using a Fresnel-zone IR of a 4x12 the same signal goes to both ears.
# Many guitar cabs are open back. A far-field IR of an open back cab through an FRFR monitor will sound very different because you're not reproducing the sound coming out of the back of the cab and bouncing off the walls.
# The sound of recorded guitar is near-field. This is what most people are used to hearing. So if you're trying to get the sound of your favorite record you won't get that with far-field IRs.

The takeaway from all this is that if you truly want the sound of amp in the room the best way to get that is to use an actual guitar cab. This isn't to say that far-field IRs are useless. They will give you a roughly similar sound to a guitar cab but it's just not the same.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/post-1801544]
One of the things I've found really useful about these (far-field IRs) is they are a good starting point for dialing the amp block in. Near-field IRs can have excessive bass and/or treble. To compensate we might end up doing strange things in the amp block which throws off the distortion character and feel. When using a far-field IR it's very similar to how the amp sounds through a conventional cab. So what I'm doing is using one of the far-field IRs to start, dial in the amp block and then choose a near-field IR. I then adjust the low/high cuts in the cab block rather than adjusting the amp block.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/aitr.176587/post-2148312]
A far-field measurement is only the response of the transducer. There's a couple ways to do far-field measurements:
# Suspend the speaker and mic in air far enough above the ground so that the ground reflection arrives after the direct signal.
# Use a ground plane measurement technique outdoors or in a space large enough that any reflections arrive after the direct signal.
A room mic is completely different and it will have the room reflections, which are desirable and give the mix "space". It will also have the response of the mic "baked in".
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/post-1822542]
# Close-micing a cabinet is not problematic. It's been done for years and solves a lot of technical issues. It may sound different than listening to that cabinet at distance but it's no more right or wrong than any other micing technique.
# Far-field has nothing to do with the picking up the sound from multiple speakers and "hearing the sound of the cab as a whole". Many cabinets have only one speaker. The far field of an acoustic radiator (i.e. speaker) is the point where the sound waves coming from the speaker behave as though the radiator is a point source. In the far field the intensity falls off by the inverse square of the distance. At distances less than the Fraunhofer distance the field is characterized by widely varying intensity due to interference. To calculate near field beam patterns you can treat the transducer as a lot of smaller point sources and find the contribution of each point source at a given point. As you move around in the near field each point source has a different phase and intensity due to distance and angle. This interference causes the intensity to vary widely as you move around.
# You can measure the far field response of a speaker in a number of ways. One way is a free field measurement. The speaker and mic are suspended far above the ground so that the multipath from the ground occurs after the direct path IR has decayed fully. This is obviously difficult. Another way is using a ground plane measurement. The microphone is placed on a smooth hard surface either outside or in a large enough room so that any reflections occur after the direct path IR has decayed. Placing the mic on the floor effectively removes the floor reflection as the direct path and reflected path are the same.
# There is no such thing as a "short impulse". An impulse is, by definition, infinitely short. Regardless, impulses are almost never used to measure IRs. Almost everyone uses sine sweeps or other wideband waveforms (PRN sequences, etc.). The length of the sweep does not need to be short and, in fact, can be quite long. The longer the sweep the better the SNR.
# A far-field IR is not a "truer" representation. It is simply the response of the cabinet in the far field. A near field IR is equally "true", it just sounds different. Far field IRs are not a panacea either. They're difficult to obtain for speakers with multiple drivers, i.e. 2x12, 4x12 because the far field is extremely far away. At 10 kHz the far field for a 4x12 is something like 100 ft. (too lazy to do the math right now).
When we listen to multiple driver speakers we are typically in the Fresnel zone. If you take an IR of a multiple driver speaker in the Fresnel zone there will be deep notches in the spectrum due to the different path length of each driver. We don't hear this though because we have two ears and our aural processing averages things out.
</blockquote>

<blockquote>
[https://www.thegearpage.net/board/index.php?threads/my-thoughts-on-reflection-free-irs.2280348/post-33067524]
A reflection free IR will NEVER sound the same as a real cab because the directivity of a monitor is very different.
</blockquote>

<blockquote>
Even a single 12" guitar cab will sound markedly different than a RFIR because the high frequency beam pattern is markedly different. Cabs with multiple speakers exacerbate the problem.

You can capture an IR of a cabinet at one point in space but it's just that: one point in space. Good monitors are designed to have smooth beam patterns with wide dispersion. A guitar cab has poor dispersion as the frequency increases. This is what causes the infamous "beaming" of high frequencies.

This causes two things. The first is a psychoacoustic effect because the sound changes rapidly with angle and our ears are a finite distance apart. One ear hears something different than the other. The other is the interaction with the room. A monitor, with its broad dispersion will send a wide range of frequencies to the various surfaces in the room. A guitar cab will send more low frequencies to the surfaces where high frequencies will be beamed. The "reverb excitation" system function is therefore different.

As a simple example consider sitting off to the side of a guitar cab and there's a wall on that side. The lower frequencies will hit that wall and reflect back to you but the higher frequencies are beamed and don't hit that wall. Now repeat that with a monitor. By design the monitor has much greater dispersion so the high frequencies hit that wall and reflect back.

The result is that guitar cabs sound "warm" in a room environment when listening off-axis (which is nearly always).

So in theory you could capture an IR at the same distance and angle as your listening point but using that IR through an FRFR monitor will simply not sound the same because of the aforementioned reasons. It may be close enough for some people but IME it's not close enough and does not offer the same experience.

And this is just the tip of the iceberg. You also have to consider near-field vs. far-field. For a guitar cab we are typically in the near-field for the higher frequencies at typical listening distances. This exacerbates the change in sound vs. angle and the resulting psychoacoustic effect.

The irony in all of this is that great pains are taken to obtain a reflection-free IR. That IR is then used in an FRFR monitor that generates reflections and the reflections generated are very different than the reflections generated by the guitar cab. That fact alone makes the whole exercise futile.

The best way to get AITR sound from something that's not a guitar cabinet is to use something that's *almost* a guitar cabinet, like a Celestion F12-X200 and then apply EQ to morph the sound. Or just use a guitar cab and a power amp and stop trying to use a hammer when you really need a screwdriver.

</blockquote>
</blockquote>

More information:
* [http://community.plm.automation.siemens.com/t5/Testing-Knowledge-Base/Sound-Fields-Free-versus-Diffuse-Field-Near-versus-Far-Field/ta-p/387463 Siemens: Sound Fields: Free versus Diffuse Field, Near versus Far Field]
* [http://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/ Fractal Audio Far-Field Session 2 IRs]
* [https://forum.fractalaudio.com/threads/tone-versus-feel-the-real-amp-in-the-room.149643/page-3#post-1776371 AlbertA's explanes the differences between near-field and far-field]

About Fractal Audio's Far-Field Session 2 IRs:

* The pack is free. The IRs can only be used with the Axe-Fx III.
* The IRs are mostly reflection-free in the first 20 ms area. Although the IRs themselves are longer, it recommended to set IR length in the Cabinet block to 1024.
* There are "A" and "B" IRs. They indicate different distances. The number which follows is the number of degrees that the cab has been rotated away from the microphone.

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>

[http://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/post-1799269]
Some minor reflections from some immovable objects within the "zone of silence". Nothing severe.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/post-1799285]
We did the best we could given the building and circumstances. There are steel posts that support the roof that were likely the source of the minor reflections. Also the environment was a bit noisy. There's a transformer that was humming. We surrounded it with bags full of foam peanuts in an attempt to reduce the noise. Statistically they aren't perfect but when we listened to them we were quite pleased. It's not difficult to obtain a far-field IR. What is difficult is finding a good space. Since we have the building the only cost to us was our time. Since no studio costs were involved we can offer these as free. If they work for you great, if they don't, nothing lost.
</blockquote>

<blockquote>
[http://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/post-1799651]
The gap at the beginning is because they aren't min-phase, they are auto-trimmed. The distance from the mic to the cab would be much greater but that's automatically removed (and we manually reduce it before-hand in the IR Capture menu).
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/post-1800363]
The magnitude of the reflections is very low. Comb filtering occurs when you add two signals where one is delayed vs. the other. If the magnitude of the two signals is equal the notch depth is infinite. As the magnitude of one decreases the depth of the notch decreases. Once you get -20 dB down or so the notch is insignificant. The amplitude of the reflections in these IRs is -30 dB down. For example if you have two equal signals and one is delayed by, say, 10 ms there will be infinite notches at 50, 150, 250, ... Hz as the delayed signal will be destructively interfere with the non-delayed signal at those frequencies (x - x = 0 => -inf dB). If the amplitude of the delayed signal drops to 1/2 the depth of that notch is now only 6 dB. I.e. x - 0.5x = 0.5x => - 6 dB. If the amplitude drops to 0.1 (-20 dB) then the notch is very small: x - 0.1x = 0.9x = -0.9 dB. At -30 dB the notch depth is x - 0.03x = 0.97 => -0.26 dB. This means ~1/2 dB amplitude variation over the spectrum. Our ears can't hear that.

</blockquote>
</blockquote>

==FullRes==

Up to 64000 samples, 1.37 sec.

FullRes IRs require more CPU power than Normal and UltraRes.

Firmware 17.xx release notes:

<blockquote>
<HR>
<blockquote>
Version 17 introduces FullResTM Impulse Response processing. FullRes processes IRs up to 64K points with zero latency using a novel technique. This provides up to 1.37 seconds of response time. Seasoned producers and engineers often mix in “Room Mics” during recording to increase the depth and liveliness of recordings. However, the typical live room has a reverb time of 500-700 milliseconds, well beyond the 20-40 ms afforded by typical IR processing. FullRes allows capturing the full response of a typical live room and even the response of small-to-medium halls and clubs. FullRes can also be used for convolution reverb applications for reverb times less than 1.37 seconds.

The IR Player block and the Cabinet block both support FullRes IRs. The last two slots of the Cabinet block support FullRes. This is sufficient to provide two room mics, a left and a right, along with two direct mics within a single Cabinet block.

The new FullRes User IR bank (Axe-Fx III Mark II and Turbo only) supports up to 64 FullRes IRs. When capturing an IR selecting the USER FR bank will automatically set the IR Type to FullRes. Likewise, when setting the IR Type to FullRes the bank will automatically be set to USER FR. FullRes IRs can be processed with minimum-phase or auto- trim, if desired. However, minimum-phase is not recommended as this will tend to destroy the reflection information.

The Scratchpad bank has been updated to support FullRes IRs (Axe-Fx III Mark II and Turbo only).

The original Axe-Fx III has less non-volatile memory and therefore does not have the necessary resources to store the IRs. The Scratchpad bank supports FullRes IRs but the data will be lost when the unit is powered off.

Added 10 FullRes IRs to the Legacy bank provided by Valhallir and York Audio (Axe-Fx III Mark II and Turbo only). These are at the end of the bank. These can be loaded into the IR Player blocks or into Slots 3 and 4 of the Cabinet blocks. Note that Slots 1 and 2 of the Cabinet blocks do not support FullRes.</blockquote></blockquote>

FullRes IRs are intended to capture "room mics" and reproduce these when recording or when playing through headphones. Room mics are sometimes mixed in to increase the depth and liveliness of recordings. They allow capturing the full response of a typical live room and even the response of small-to-medium halls and clubs. [https://forum.fractalaudio.com/threads/aitr.176587/post-2145064]

The expected approach is to combine a regular short (close-mic'd) IR with two (longer) room mics for ambience. This separation allows separate control over the direct sound and the (stereo) acoustic space.</blockquote>

[https://www.fractalaudio.com/tmp/AITR_Toad.mp3 Recording example]

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/aitr.176587/post-2145657]
Normal IRs are 2K. FullRes IRs are 32 times larger so an entire bank would provide 32 FullRes slots.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-release-version-17-00-public-beta-2.176961/post-2152632]
So I came up with a solution for Mark I owners: the Scratchpad bank supports both standard and FullRes IRs. Obviously you'll lose your IR when you power off.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/aitr.176587/post-2145732]
(Axe-Fx III Mk I) It has plenty of memory for firmware updates. It has limited NV memory for user data storage because at the time it was designed the FLASH chips used were the largest capacity available. The Mark II has larger capacity FLASH chips because they're available now.
</blockquote>

<blockquote>
[https://www.thegearpage.net/board/index.php?threads/aitr-cliff-is-brewing-something-new.2287174/page-3#post-33207828]
There are two cab blocks and each block supports two FullRes IRs so you could, in theory, do stereo 2.66 seconds. We went back and forth on how much time to support. At first I was thinking 2.66 seconds but that would double the CPU use and cut the number of available IRs in half. A survey of the literature showed that the reverb time of most acoustic spaces where recordings are done is less than a second so 1.33 seemed the best balance. I plotted the IRs of a bunch of the room mic IRs I have and the reverb time was typically around 500 ms which is consistent my experience and the literature.
</blockquote>

<blockquote>
[https://www.thegearpage.net/board/index.php?threads/aitr-cliff-is-brewing-something-new.2287174/page-3#post-33207828]
The point of FullRes IRs is to add some room sound to your recordings and/or headphone playing. To do this you would mix conventional IRs with FullRes IRs.

</blockquote>
</blockquote>

FullRes IRs require more CPU power than Normal and UltraRes IRs. Also, they are relatively large and require some time to load. Therefore, gapless switching (channels, scenes, presets) is not supported when using Full-Res IRs.

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>
[https://forum.fractalaudio.com/threads/not-yet-fixed-gap-with-amp-cab-irp-channel-changes.200360/#post-2541456]
Full-Res (room) IRs are large and take a long time to load. Gapless switching is not supported when using Full-Res IRs.
</blockquote>
</blockquote>

To support FullRes: several adjustments have been made:

* Only slots 3 and 4 of the [[Cab block]] support FullRes IRs for stereo reproduction (left+right room mics). So does the [[IR Player block]].
* Full Res IR files will not be visible unless you select them in slots 3 or 4.
* [[IR Capture]] supports capturing FullRes IRs.
* The Axe-Fx III Mk II has a dedicated user bank for FullRes IRs.
* FullRes IRs can be processed with minimum-phase or auto-trim, if desired. However, minimum-phase is not recommended as this will tend to destroy the reflection information.
* A FullRes Scratchpad is available for auditioning IRs during the capture process.
* [[Cab-Lab]] will be updated to support FullRes IR captures and management. [https://forum.fractalaudio.com/threads/aitr.176587/post-2145186]

About FullRes and Far-field IRs: not the same thing. They both capture the sound at longer distances, but where far-field IRs capture the sound coming directly from the speaker, FullRes IRs are intended for capturing the room (ambience) only. Both types of IRs are aimed at reproducing the sound of a guitar speaker as we hear it "in the room", as opposed to close-micing and recording a speaker. Where far-field IRs should have the least possible "room reflections", FullRes relies on them. [https://forum.fractalaudio.com/threads/aitr.176587/post-2146858]

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>

<blockquote>
[https://forum.fractalaudio.com/threads/aitr.176587/post-2148312]
A far-field measurement is only the response of the transducer. There's a couple ways to do far-field measurements:
# Suspend the speaker and mic in air far enough above the ground so that the ground reflection arrives after the direct signal.
# Use a ground plane measurement technique outdoors or in a space large enough that any reflections arrive after the direct signal.
A room mic is completely different and it will have the room reflections, which are desirable and give the mix "space". It will also have the response of the mic "baked in".

</blockquote>
</blockquote>

FullRes also allows the use of convolution reverbs, shorter than 1.33 seconds. [https://forum.fractalaudio.com/threads/aitr.176587/post-2145186]

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>

<blockquote>
[https://forum.fractalaudio.com/threads/aitr.176587/post-2146237]
You can ALSO use FullRes IRs to do short-to-medium convolution reverbs. If you have some reverb IRs you can convert them to FullRes IR format and load them in the IR Player block and use that as a reverb.
</blockquote>

<blockquote>
[https://forum.fractalaudio.com/threads/aitr.176587/post-2146237]
Algorithmic reverb is considered to be superior to convolution reverb because algorithmic reverb can be perceptually tuned. From a perceptual standpoint the ideal reverb is not found in typical reverberant spaces. See the work done by Griesinger, et. al. on perceptual reverberation.

</blockquote>
</blockquote>

The factory FullRes IR in the Legacy bank are:

* 190 — 4x12 V2 Viper Room L (Val)
* 191 — 4x12 V2 Viper Room R (Val)
* 192 — 2x10 Vibrato Lux Room L (YA)
* 193 — 2x10 Vibrato Lux Room R (YA)
* 194 — 2x12 Class A 30W Room L (YA)
* 195 — 2x12 Class A 30W Room r (YA)
* 196 — 4x12 Brit Greenback Room L (YA)
* 197 — 4x12 Brit Greenback Room R (YA)
* 198 — 4x12 Recto Room L (YA)
* 199 — 4x12 Recto Room R (YA)

==DynaCab==

2048 samples.

Part of DynaCab cabinet modeling, introduced in firmware 22 and later for the Axe-Fx III (and corresponding FM3 and FM9 firmware).

Read this: [[Cab_block#DynaCabs|DynaCabs]]

=Far-field IRs and close-mixed IRs=

See above.

=Interesting IRs=

'''Commercial and free IRs'''

The processors contain a lot of factory cabs, aka stock cabs. [[Cabinet models list]]

You can also create your own IRs with [[IR Capture]] or software, acquire IRs from sources such as [http://axechange.fractalaudio.com Axe-Change], or from commercial vendors, including Fractal Audio.

Fractal Audio's free IR libraries:

* [http://www.fractalaudio.com/downloads/misc/Cab-Pack-1-Wellspring-Sound.zip Wellspring Sound (Vol. 1)]
* [https://forum.fractalaudio.com/threads/non-minimum-phase-irs.146046/ Wellspring in non-MPT format]
* [http://www.fractalaudio.com/downloads/misc/Cab-Pack-2-Mad-Oak.zip Mad Oak Studio]
* [http://www.fractalaudio.com/accurate.php IRs from a session with Larry Mitchell]
* [http://forum.fractalaudio.com/threads/free-far-field-session-2-cab-pack-for-axe-fx-users.151232/ Fractal Audio's Far-Field Session 2 IRs]
* [https://forum.fractalaudio.com/threads/free-irs-in-celebration-of-the-80th-birthday-of-frank-zappa.168497/#post-2024072 Free IRs in Celebration of the 80th Birthday of Frank Zappa]
* [https://forum.fractalaudio.com/threads/free-hj-4x12-rca-cab-pack.156177/ Free HJ 4x12 RCA Cab Pack]

Some commercial manufacturers provide free impulse responses. There are also quite a few popular impulse responses available in the public domain. Some examples:

* [https://axechange.fractalaudio.com/detail.php?cab=377 gtrbody] — Adds the resonant sound of an acoustic guitar body.
* cello_body — Adds the resonant sound of a cello.
* [https://axechange.fractalaudio.com/detail.php?cab=86 GuitarHack ThisOne V30]

'''Acoustic instruments'''

When recreating the sound of acoustic instruments (acoustic guitar, cello, violin etc.), an IR of an acoustic body may improve the sound. You can find some on [[Axe-Change]].

Acoustic sounds benefit from long IRs with some room ambience, so UltraRes or even FullRes IRs are preferred.

'''Flat IR'''

The Factory 2 bank has a "totally flat" IR.

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>

Allows to individually adjust Mic Distance for phase adjustment of the "DI", while still enjoying the Preamp modeling and Mix controls of the Cab block without complex routings.

The totally flat cab has no filtering and sounds absolutely wretched. It's only there for diagnostic and special effect purposes.
</blockquote>
</blockquote>

=IR Capture=

Read this: [[IR Capture]]

=Tone Matching=

Read this: [[Tone Match block]]

[[Tone Match block#Use Tone Match to capture an IR|Use Tone Match to capture an IR]]

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>

<blockquote>
[http://forum.fractalaudio.com/threads/how-about-some-micing-tips-for-tone-matching.62089/#post-771270]
The IR is vastly more important. Tone Matching is a nifty feature and certainly useful but you'll get far more satisfaction by concentrating on capturing good IRs. The single most important aspect of recording guitar amps is micing the amp. Therefore the single most important aspect of using your Axe-Fx is the IR. People are too hung up on "matching" or "profiling" an amp but fail to realize that when you are doing that you are basically capturing an IR. If you capture the IR separately now you have an IR that is fully separated from the amp and therefore can be used with all models. Matching and profiling cannot mathematically separate the amp's frequency response from the cabinet frequency response. Once you do this you'll be surprised at how accurate the amp models are. I do this all the time and find Tone Matching is unnecessary now (in fact many of the amp models have had their built-in matching data removed in the latest firmware). Any differences between the model and the real amp are so minuscule as to be immaterial. A little tweak of the tone stack or EQ is usually enough to remove and differences. Besides, once you get into mixing you'll realize that you'll be applying EQ anyways so tiny differences in EQ are irrelevant. Moving the mic just a small amount drastically changes the sound. The best producers have mastered micing. You can only fix so much via EQ since EQ is essentially painting with a broad brush where mic technique is akin to using a fine-point brush.

There is NO substitute for shooting an IR of the cab. IMO, this is the single most important thing you can do. Everything else is attempting to learn the cab IR through an indirect method and then you have inseparability. If you shoot the IR then do a Tone Match you can change the cab after or do another IR with a different mic or mic position and your matching data is still valid.

</blockquote>
</blockquote>

= Volterra kernels=

<blockquote>'''FRACTAL AUDIO QUOTES'''<HR>
<blockquote>

[http://forum.fractalaudio.com/threads/will-we-see-improvements-new-tech-regarding-speaker-cabinets.135191/page-2#post-1599277]
The Axe-Fx III (and II) actually capture the Volterra kernels when doing an IR capture (it's hidden in the firmware for possible future use). I've studied dozens upon dozens of them and the kernels above first order (the first order kernel is the linear IR) are so small as to be inaudible. The distortion from an amp is orders of magnitude greater even when using a clean amp. The only significant nonlinear thing I've measured that speakers do is thermal compression (that we model already) and "cone cry" which sounds like sh*t. Jay Mitchell is probably the leading authority on speaker design and he has stated pretty much the same thing. I'm all for improvements but they need to be real improvements. I've sat here countless times comparing an IR to the actual speaker with a mic on it doing blind A/B tests and can NEVER tell the difference and I think my ears are pretty good. I dug through my Matlab stuff and found this. (graph) This is an IR of a speaker taken twice. The first time the drive level is around 1W (in red). The second time the amp was turned way up, I would estimate at least 50W (in blue). As you can see the difference is extremely small. There's a small difference from 10 Hz and down which is way below the reproduction range of any system and a difference way up at Nyquist (24 kHz) but that's 100 dB down (!). Furthermore we don't know if the tiny differences are from the speaker or from the amp or the mic or the mic preamp. I should add that speakers can and do distort (when Xmax is exceeded) but it's not a pleasant sound. Since the displacement of the cone is the inverse of the frequency the low frequencies are distorted which is the opposite of what you want when creating "pleasing distortion". Speaker distortion is flubby, flabby and farty. The Axe-Fx II and III can simulate that, if desired, using the Speaker Drive parameter in the Amp block. I always set it to zero. There are probably some other modes that cause distortion but, again, these are dwarfed by the distortion of the amp. The only other significant one I've experienced is cone cry. Manufacturers go to great lengths to prevent it from happening. I have a speaker here that does it. Whenever I play a high F it cries and it's annoying.
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<blockquote>
[https://forum.fractalaudio.com/threads/anyone-try-using-ua-ox-stomp-for-their-cabs.198601/post-2470708]
If you want "nonlinear IRs" you need to use something like Volterra kernels. I've experimented with this and, in fact, the Speaker Drive and Speaker Thump parameters essentially create higher order Volterra kernels based on various amp parameters. The harsh reality is that speakers are pretty darn linear. Things like cone cry are design/manufacturing defects and shouldn't be modeled IMO. There is some low frequency distortion and we model that but a classic, linear IR is the gold standard for replicating the sound of a speaker. Armchair pundits like to pontificate about "IRs are the weak link, blah, blah" but they're typical internet loudmouths who have little to no expertise and would fail a double-blind test every time. Now, thermal compression is definitely a factor and we model that quite extensively. As you play the voice coil heats up and its resistance increases. The radiation resistance does NOT change, however, so the resulting acoustic output decreases. There's a lot more involved when simulating a tube amp though and I can't disclose that stuff because it's proprietary. Another factor is the actual speaker impedance. It's a function of displacement. Again, we model this extensively. As the speaker moves in/out of the magnet the Bl product changes and therefore the inductance and various other electrical parameters change.

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=Videos=

[[video:Wampler-IR]]
[[video:AdamSteel-IR]]
[[video:Sonic-IR]]
[[video:PeteThorn-CelestionIRs]]
[[video:Dolce-AcGuitar]]

[[category:Axe-Fx2]]
[[category:Axe-Fx3]]
[[category:FM3]]
[[category:FM9]]
[[category:AX8]]
[[category:Sounds]]
[[category:All]]