Frequently Asked Questions

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Axe-Fx Features

What amps does the Axe-Fx simulate?

See the List of amp simulations

What mics does the Axe-Fx simulate?

See the Description of Mic Models

What drive pedals does the Axe-Fx simulate?

See the Description of drive models

What effects does the Axe-Fx offer?

See the Feature comparison

How does the Spillover work on the Axe-Fx?

See Spillover

What poweramp is used for the Brit pre Model?

The preamp part is a JMP-1. The power amp is from the JCM800.

What are the frequencies and Q of the Global EQ?

See the Global parameters

What is the Boost parameter on the Amp block and what exactly does it do?

The amp boost is just a 12 dB boost right at the start of the amp block. It's the exactly the same as using the filter block set to null with the level set to +12db.

Can I control the amp block parameters like the boost switch, Eq, or drive parameter w/ MIDI CCs?

Yes, you can control the drive parameter in the effects block. No, you can not control the boost switch or EQ settings. The solution for the boost switch is to use the filter block and set the type to NULL. The filter block has a gain range of -20 to +20dB expressely so that you can use it as a gain control into the amp block. The boost switch adds +12db of gain, set the filter level to +12db to match.

Does the master volume in the amp block effect the tone?

Yes, in fact for clean tones the Drive control should be set fairly low and the Master set very high. On a real "Blackface", for instance, the Master is essentially maxed since that amp has no master volume. A Blackface typically achieves full power at around 10-11 o'clock on the volume (Drive). It's also insanely loud. Beyond that the everything starts to saturate and clip.

If you set the Master low and the drive high, for clean tones, the low end will tend to get muddy. Good cleans are obtained with little, if any, preamp distortion and a nice amount of power amp distortion. Power amp distortion has a much different character and tends to be glassy and bouncy. Preamp distortion is rougher and more compressed.

For more detailed information see the Amp_simulator

Where should the master volume be set to emulate amps w/o a master volume?

The master volume is such that near maximum (4:00 o'clock or so) is equivalent if the modeled amp had no master volume. As always use your ears to fine-tune.

When controlling the db levels of a block with an expression pedal, what is the formula for determing what percentage relates to what db level?

The range of level in most effects blocks is 63.5db(-50db+13.5db).

78.7% should be 0db (50/63.5)

-20db should = 47.2%(30/63.5)

1db= about 1.57%

How do I get a pedal switch boost effect from the Axe-Fx?

A boost effect can be easily achieved using the Filter block. Simply set TYPE to NULL and adjust the LEVEL control for the amount of boost desired. Bypass the Filter for normal operation, then engage it for a boost. For a gain boost, place it before a Drive or Amp block. For a simple volume boost, place it after those blocks or at the very end of the chain. Keep in mind the boost will push the drive in a Delay placed after it, but cutting the volume of the output of a delay or reverb could sound unnatural.

How can I get more than 4 taps from the Quadtap multidelay?

Put 2 Quadtap multidelays in parallel.

How do I set the high and low cut in the multidelay?

In order to set the high and lo cut to the multi delay, you can apply this formula:

Freg = sqrt(f_high * f_low)

Q = Freq / (f_high - f_low)

So, for a lowcut of 20 Hz and a hicut of 2.5 kHz:

Freq = sqrt(2500 * 20) = 224

Q = 224 / (2480) = 0.09 (0.1 is close enough)

Enter the respective results in the FREQ and Q parameters

Note: be sure Master Q is set = 1.0

How do I get rid of zipper noise from my expression pedal?

When using an expression pedal or certain Controllers, it is possible to sometimes hear a rough transition. This choppy sound, or "zipper noise", is a result of discontinuities or jumps in the controller data, often resulting from the limited resolution in MIDI CC values. The Axe-Fx has easy fix for these issues. In the Modifier settings, there is a DAMPING parameter for smoothing input data. Setting it to 4 or 8 ms should smooth out most expression pedal issues without causing any response time lag.

What does the warmth parameter do in the amp block?

Warmth models the "leakage inductance" of the output transformer. Higher values equate to higher leakage inductance. The net effect is a warming of the sound since the highs are attenuated.

Why is the Save to Flash feature only on the Standard and not the Ultra

The Ultra doesn't have that feature because all the extra effects use up more FLASH memory space so there isn't enough space left to save the presets in FLASH.

Axe-Fx Technical Questions

Will the Axe-Fx work in both Europe and the United States?

Yes - the Axe has universal power input, 100-240VAC, 50-60Hz.

What is the processing latency of the Axe-Fx?

The processing latency is constant and very short. That was a design goal. It is around 600 microseconds IIRC. That's equivalent to being only 8 inches further away from the speakers. One thing many manufacturers do is use fairly large block sizes to keep function overhead from wasting clock cycles. The block size in the Axe-Fx is small which wastes some clock cycles but keeps latency down.

The total latency is around 1 ms. There is 600us processing latency plus an additonal 400us of converter latency. If you use the loop you get another 400 us due to another codec in the chain.

Does the Axe FX have an issue with phantom power being turned on at the mixing board?

No. There's blocking capacitors on the outputs. The outputs are bypassed with high-quality film types, which is something no one does anymore for cost reasons.

What is the patch change time for the Axe-Fx?

Preset switching time is around 20-25 ms with delay spillover off. With delay spillover on, it's around 25-30 ms.

What is the backup battery for the Axe-Fx?

Standard CR2450 lithium battery.

Do the output knobs on the front have any influence on the level of the digital out?


What is the difference in processor speed and memory between Ultra and Standard?

20% faster. 6x the memory.

My Axe-FX has duplicate factory preset patches in banks A and B and bank C is empty. Is this right?

This was true some firmware versions ago. Currently the Standard has two banks (A & B) filled with different factory presets while the third bank (C) is empty. Since version 2.23 the Ultra has also Bank C filled with factory presets. You can download the factory presets here :

Standard :

Ultra :

Many of the Ultra presets may also work on the Standard and vice versa. Interchanging them will not harm your Axe-Fx.

Which is more transparent the Front or Rear inputs?

Neither input is more "transparent" than the other. The front input is optimized for the signal level of an electric guitar. The rear inputs are line-level and work best with line-level equipment.

The front input also has hardware processing to lower the perceived noise floor. This processing requires additional software processing. By switching the input selector to rear you defeat the software processing and distort the frequency response of anything plugged into the front greatly.

Usually the front input will sound best with an instrument due to the greater gain and lower perceived noise floor. But you MUST match the input selector to the actual input you are using.

Will the Mono output settings automatically disable all enhancers and change all stereo effects so that I get a mono sign with no phase issues and other unwanted results?

No. Using the Mono L->R output selection ought to take care of most phase issues; however, the mono output settings will not change any other parameters. Stereo effects may still not transfer to mono as intended. As with everything, use your ears and test.

Can the Axe-Fx's digital I/O run at 44.1 kHz, or any values other than 48 kHz?

No, it's 48 kHz only. The rationale is that software on a computer could do a better job resampling than a hardware chip.

The reason that the native sampling rate is fixed was a hardware design choice. By placing the A/D and D/A clock very close to the converters and using a fixed, dedicated clock you get much better performance since there's much less clock jitter. As soon as you start putting a clock through logic circuitry and routing it all over the place you introduce jitter and the converter performance degrades.

Firmware Questions

How do you update the firmware?

See Firmware install notes

Where can I get the latest firmware?

New firmware releases are announced on the Fractal/Atomic News page and are available from the Fractal Audio Support Page

Notification of new firmware is also typically posted to the Axe-Fx forums by Fractal Audio Systems. Occasionally, the community will also post notification of the new firmware.

Where can I get prior firmware or AxeEdit versions?

Older firmware versions are [still] stored on the FAS site.

The URL (link) format prior firmware versions is as follows. 
  • where N_NN = major version_minor version. eg: 10_00, 10_01, 9_01, 9_03, 7_04
  • model = ultra or standard (no caps)
NOTE: versions prior to 10 do NOT have a "0" (zero) in front of them, so "ultra09_03/"  is NOT VALID.

The URL must be EXACT or it will fail. So, for example, Ultra firmware v 10.* can be found here:

Standard v10.* here:

Earlier versions (eg: 9.*) would be stored like this:

Figure out which firmware you need, build the link, stick it in your browser and see if it works. eg: Firmware v7.04 location would be

Exactly the same type of URL format applies for AxeEdit, but with a different domain name. Links to prior editor versions eg:0.9.171 [BETA] can be built by simply changing the version number in the URL shown below. Current release (191) URL is:

If you want to download the prior version (0.9.171), change the version to 171 and paste the URL in your browser. Apply rules above to get earlier versions.

What are the differences in firmware revisions?

See Firmware history

The firmware versions for the Standard and the Ultra are not always in sync. Sometimes there is a newer version available for the Ultra and not the Standard, and sometimes there is a newer version available for the Standard and not the Ultra.

Do I have to update/send/download presets when I download a new firmware?

In most cases, no! Firmware updates and preset banks are separate files. If you update/send/download a new preset bank to the Axe-Fx you will overwrite any changes you made to the existing presets in that bank of your Axe-Fx.

However, firmware updates may change the way certain parameters behave, so manual preset updates are sometimes suggested. Always check the Firmware history for details on new parameters or updates to parameters that already exist.

Sometimes the factory presets are updated. These can be found on Fractal Audio's web site in the Documents subfolder as individual bank files. Remember to save/backup your custom presets to your computer before updating/sending/downloading the new banks to your Axe-Fx.

Operational Questions

How do I upload or download patches to the axe-fx

Use the Axe-Fx editor or
See How to download/upload patches

Is there anyway to fast forward through presets using the dial?

Yes, turning the dial quickly will fast-forward thru the presets. Turning it slowly you will feel the knob click for each preset change. The key is to not spin it too fast. If you spin the knob too quickly the dial switches will bounce and reject the data. Maintain an even rotation rate and the "acceleration" will engage and it will fast-forward. There's a new algorithm available for the rotary encoder logic that improves the behavior of the dial which comes by default on newer built units. If you have the old algorithm, you can send it to Fractal Audio to install the new one. Units shipped after August 2007 all have the newer algorithm.

Fractal Audio Questions

Who is Cliff Chase?

See Cliff Chase interview


I hear people talking about what speakers they use and I see the term FRFR. What is FRFR?

Quote godprobe:FRFR means "full range, flat response"

and that (ideally) means... 20Hz - 20kHz, ruler flat... all frequencies within the 20 to 20 range are replicated exactly as they're sent in.

that's the goal of an FRFR speaker... represent the sound going into it as accurately as possible.

this is in contrast to guitar cabinets and other speakers that "color" the sound dramatically... they may boost or cut lows, mids, or highs and may not cover the full frequency spectrum in the first place