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Difference between revisions of "User:Greg Ferguson"

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m (Modified quoting for comments extracted from firmware 28.01 readme for increased readability)
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=Compressor types=
 
  
The Compressor block was completely overhauled in firmware 28 for the Axe-Fx III.
 
 
Note that CPU usage varies a lot among the types.
 
 
; Analog Compressor : Natural soft-knee response, capturing the vibe of the classic compressors of the 70s and 80s.
 
; Analog Sustainer : The same with upwards compression.
 
 
<blockquote>
 
'''FRACTAL AUDIO QUOTES'''
 
<HR>
 
<blockquote>
 
[https://forum.fractalaudio.com/threads/axe-fx-firmware-version-21-02-public-beta-beta-2.191173/post-2376038]
 
Upwards compressors INCREASE gain. Downwards compressors DECREASE gain.
 
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[https://forum.fractalaudio.com/threads/axe-fx-firmware-version-21-02-public-beta-beta-2.191173/post-2375817]
 
A sustainer is an upwards compressor. It increases gain when the signal is below the threshold. Therefore it will increase noise. You may want to use a gate to kill the noise.
 
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; Classic VCA Compressor : It's not disclosed what this is based on.
 
 
; Compander : The Transients control adjusts the transient modification. Values less than zero soften the attack, value greater than zero emphasize the attack.
 
 
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'''FRACTAL AUDIO QUOTES'''
 
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[https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-release-version-16-03.174033/post-2109538]
 
A Compander is a compressor followed by an expander. If the time constant of the compressor and expander are the same (and the "channel" is perfect, i.e. linear and lossless) then a Compander is transparent. If you change the time constant of one vs. the other the transients will become distorted. The "Transients" knob controls the time constant mismatch. Negative values smooth the transients, positive values enhance the transients. A Compander with transient enhancement can be used on kick drums, bass, etc. to add punch. Transient reduction can be used to reduce plosives. For guitar you can use the Compander to add or remove pick attack.
 
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[https://forum.fractalaudio.com/threads/delay-block-update.173708/post-2104201]
 
The first step in adding compansion to the delay block was creating a compander algorithm. So I created a Compander type first in the Compressor block. Once that was working I used that algorithm in the Delay block. The Compander allows you to set the Ratio, Time, Transients and Level. Turn Transients down and the attack is reduced, turn it up and the attack is enhanced. You can use it with kick drum to enhance the punch, put it on vocals to reduce plosives, etc.
 
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; Dynami-Comp Classic | Modern | Soft
 
:Based on [https://www.guitarworld.com/features/mxr-dyna-comp-compressor-pedal MXR’s M-102 Dyna Comp pedal].
 
 
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'''FRACTAL AUDIO QUOTES'''
 
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<blockquote>
 
Added in firmware [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-28-00-release.211568/ v.28.01]:
 
 
* New Dynami-Comp algorithm:
 
** New algorithm accurately models various nonlinearities for faithful reproduction.
 
** Added Knee Type to allow varying the knee shape.
 
** Added Tone control (like in various clones).
 
** Added Drive control. The Drive control allows overdriving the OTA which can be used to add saturation. The control is preset when selecting one of the Dynami-Comp types but can be altered by the user.
 
** Added Input/Output graph.
 
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[https://forum.fractalaudio.com/threads/axe-fx-firmware-version-21-02-public-beta-beta-2.191173/post-2375490]
 
The Dynamicomp type is based on a Dynacomp.
 
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<blockquote>
 
[https://forum.fractalaudio.com/threads/compressor-attack-release-default-settings.183692/post-2260540]
 
The attack time in our reference pedal is measured as 3.6ms. The attack time is dynamic. The greater the output of the compression circuit the faster the attack time.
 
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[https://forum.fractalaudio.com/threads/compressor-attack-release-default-settings.183692/post-2260136]
 
The attack time is actually dynamic and a function of the input level. Our algorithm models this. The default value is 3.6ms and is the maximum attack time. The higher the input level, the lower the attack time.
 
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[https://forum.fractalaudio.com/threads/axe-fx-firmware-version-21-02-public-beta-beta-2.191173/post-2375507]
 
Our model is based on the original ones that used the CA3080A. New ones use an LM13700.
 
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[https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-28-00-public-beta-beta-4.211395/#post-2643757]
 
A Ross-type circuit.
 
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</blockquote>
 
 
; Dynamics Processor : Allows compression or expansion with a single control. When set to negative values, the block compresses the signal. When set to positive values, the block expands the signal. This is also available in the Amp block.
 
 
; Econo-Dyno-Comp : Low-CPU version of Dynami-Comp algorithm. This replaces the former PEDAL 1 type.
 
 
; JFET Pedal Compressor
 
<blockquote>
 
'''FRACTAL AUDIO QUOTES'''
 
<hr>
 
<blockquote>
 
Added in firmware [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-28-00-release.211568/ v.28.01]:
 
 
* New JFET Pedal Algorithm:
 
** Based on pedals with a JFET as the shunt resistor in a non-inverting op-amp configuration.
 
** Replaces the JFET Sustainer type.
 
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</blockquote>
 
 
; JFET Studio Compressor
 
: Based on classic JFET (Field Effect Transistor) rackmount compressors, e.g. Urei 1176.
 
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'''FRACTAL AUDIO QUOTES'''
 
<hr>
 
<blockquote>
 
Added in firmware [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-28-00-release.211568/ v.28.01]:
 
 
* New JFET Compressor algorithm:
 
** Based on classic JFET rackmount compressors.
 
** Dynamic time constants.
 
** The Attack and Release times are the “native” times of the detector. The actual Attack and Release times will be much shorter (about 5 times). The native range of Attack Time for an 1176 is 0.1 ms to 5.5 ms. ** The Release Time range is 59 ms to 1.1 s.
 
** Due to the design of these compressors the minimum compression ratio is 4:1. Any settings below 4.0 will be clamped at 4:1.
 
** Unlike the actual hardware the algorithm’s threshold is variable so instead of varying the input and output gains we give you a more convenient method (and Automatic Makeup Gain).
 
** Due to the very fast attack times these types of compressors will distort. This is often used for effect. Low frequencies are distorted more.
 
** The “Drive” control allows overdriving the output stage for added distortion.
 
** Perfect for fattening up your sound and adding grit. Works well as a “finishing” compressor at the end of a chain (usually before time-based effects). Also great for vocals, bass and drums.
 
</blockquote>
 
</blockquote>
 
 
; Modern VCA Compressor : It's not disclosed what this is based on.
 
 
; Optical Compressor
 
: Based on classic optical rackmount compressors, e.g. LA-2A, famous for their smooth sound.
 
 
<blockquote>
 
'''FRACTAL AUDIO QUOTES'''
 
<hr>
 
<blockquote>
 
Added in firmware [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-28-00-release.211568/ v.28.01]:
 
 
* New Optical Compressor Algorithm:
 
** Based on classic optical rackmount compressors.
 
** Times are “doubly dynamic”. The times are dynamic due to the feedback topology of the compressor and the attack and release times of the photocell are also dynamic. The Attack and Release Time controls set the nominal times of the photocell. However, the times will vary with the program level.
 
** Due to the design of these compressors the minimum compression ratio is 4:1. Any settings below 4.0 will be clamped at 4:1.
 
** Whereas hardware optical compressors typically have a fixed compression ratio (usually about 4:1) and a limiting option this algorithm allows adjusting the ratio from 4:1 to (nearly) infinite.
 
** Rather than input/output gain controls the algorithm allows adjusting the threshold instead which requires less fiddling with the makeup gain.
 
** The Emphasis control replicates the internal “Limiter Response” adjustment. This control may be on the front panel of some clones and the operation may be reversed depending upon the manufacturer. The Emphasis Frequency control allows shifting the frequency range of the curve.
 
** The “Drive” control allows overdriving the output stage for added distortion.
 
** The smooth attack and release characteristics of this type make it ideal for vocals and acoustic instrument sources.
 
</blockquote>
 
</blockquote>
 
 
; Rockguy Compressor
 
: Based on the (Tom Scholz) Rockman Guitar Compressor. [https://forum.fractalaudio.com/threads/implemented-rockman-guitar-compressor.209143/page-7#post-2643914]
 
 
<blockquote>
 
'''FRACTAL AUDIO QUOTES'''
 
<hr>
 
<blockquote>
 
Added in firmware [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-28-00-release.211568/ v.28.01]:
 
 
* Added Rockguy Compressor Type:
 
** Similar to the JFET Pedal algorithm mentioned above but with dynamic release time and several other enhancements.
 
</blockquote>
 
</blockquote>
 
 
; Vari-Mu Tube Compressor
 
: Previously called Tube Compressor.
 
 
<blockquote>
 
'''FRACTAL AUDIO QUOTES'''
 
<hr>
 
<blockquote>
 
Added in firmware [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-28-00-release.211568/ v.28.01]:
 
 
* New Tube Compressor Algorithm (now called “Vari-Mu Tube Compressor”):
 
** Based on a tube compressor using “remote-cutoff” tubes for gain control.
 
** Dynamic attack times.
 
** The actual compression ratio is somewhat nebulous due to the nature of the circuit but, in general, the minimum ratio is about 2:1 and the maximum ratio is about 20:1. The Threshold and Compression controls ** interact. The graph assists with adjusting the controls.
 
** This compressor has big, swoopy compression curves and a warm tone making it useful for adding “glue” to a track or mix.
 
** The “Drive” control allows overdriving the output stage for added distortion.
 
</blockquote>
 
</blockquote>
 
 
; VCA Bus Compressor
 
 
<blockquote>
 
'''FRACTAL AUDIO QUOTES'''
 
<hr>
 
<blockquote>
 
Added in firmware [https://forum.fractalaudio.com/threads/axe-fx-iii-firmware-28-00-release.211568/ v.28.01]:
 
 
New “VCA Bus Compressor” algorithm:
 
* Based on a VCA feedback design (e.g., SSL Bus Compressor).
 
* Dynamic time constants. Extremely fast attack times are achievable as the actual attack time is always less than the programmed time (decreases dynamically).
 
* This algorithm replaces the Studio FB Compressor.
 
* Auto Att/Rel has been removed as it is no longer applicable.
 
</blockquote>
 
</blockquote>
 
; VCA FB Sustainer
 
 
; VCA FF Sustainer
 
 
Feedforward (FF) compressors compress “upwards” as opposed to a downwards compressor. They yield a different sound (smooth release and “fat” compression) than feedback compressors (FB). Feedback compressors can result in distortion at extreme control settings.
 
 
[[image:comp1.jpeg|600px]]
 
 
[[image:comp2.jpg|700px]]
 

Revision as of 20:28, 3 June 2025