Always consult the Owners Manuals first.
Note: the wiki is currently being updated with information about the FM3.

Wah block

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EV-1 rear.png

Available on which products

  • Axe-Fx III: 2 blocks
  • FM3: 2 blocks
  • Axe-Fx II: 2 blocks
  • AX8: 1 block
  • FX8: 2 blocks

Channels or X/Y switching

  • Axe-Fx III and MF3: 4 channels
  • Axe-Fx II: X/Y
  • AX8: X/Y
  • FX8: X/Y

Wah types

  • FAS Standard – equivalent to the “Bandpass” setting in earlier firmware
  • Clyde – based on an original Vox Clyde McCoy wah
  • Cry Babe – based on a Dunlop Cry Baby
  • VX846 – based on a Vox V846-HW handwired wah
  • Color-Tone – based on a Colorsound wah
  • Funk – based on the “Shaft” sound
  • Mortal – based on a Morley wah/volume pedal
  • VX485 – based on a Vox V845

Pictures of the real pedals, by MDProd

Other Wah pedals can be emulated by copying frequency range settings from the manufacturer's data:

Position of the Wah block on the grid

Just like actual Wah pedals, the Wah block is usually placed before the amp.

Unless you want to sound like Tom Morello, in which case it should be placed after the Amp block.

Set up a Wah pedal

Read this: Remote control, pedals and switches

Make sure to calibrate the pedal on the hardware!

Auto-engage the Wah

Similar to an optical Wah pedal, you can engage the Wah block automatically when moving the assigned expression pedal. Especially handy when using a spring-loaded pedal. To accomplish this, set Auto-Engage in the modifier menu of the CONTROL parameter in the Wah block to either a speed or position controlled setting. More information


Parameters table

Parameter Axe-Fx III / FM3 Axe-Fx II AX8 / FX8
Type yes yes yes
Wah Control yes yes yes
Control Taper yes yes yes
Resonance Q yes yes yes
Q Tracking yes yes yes
Low Cut Frequency yes yes yes
Minimum and Maximum Frequency yes yes yes
Fat yes yes yes
Drive yes yes yes
Inductor Bias / Coil Bias yes yes yes
Graphic EQ yes no no


"Tracking controls how much the Q changes with the Control knob. The Q in a wah is not constant. The amount of Q change varies from brand-to-brand and model-to-model. It even varies between identical models due to component tolerances." source


"FAT is actually a mix control. It adds dry signal so you can't ever get 100% dry. At max FAT it's 50/50." source

Max Freq

Decreasing the maximum frequency allows a high gain Wah tone to cut better through the mix.

Coil Bias / Inductor Bias

This allows the user to adjust the DC offset of the virtual inductor.

"Over time the inductors build up some slight permanent magnetism due to finite DC current through them. This causes asymmetric distortion." source


8-band Graphic EQ (firmware Ares).

Output Level

When changing the Wah type, the output level is adjusted automatically because the output of the models has been matched to the original pedals. source

"A typical wah has a gain of around 16 dB but it's a bandpass (sort of) response. If your amp is set clean then the output of the amp block will increase by 16 dB when the wah is engaged. Most amps have a response that rises with frequency response. So if the output of the amp block without the wah engaged was, say, 12 dB below full-scale at the high frequencies, it will be 4 dB over full-scale when the wah is engaged." source

Tips and tricks

Seek Wah

The Seek Wah is a pedal by ZVEX, which is based on a sequenced filter pattern. For an equivalent effect, assign the Sequencer internal controller to the Wah Control parameter. For a more pronounced effect, add a Formant block, attached to the same controller.

Auto Wah

Read this: Filter block

Fixed Wah

Simulate a fixed Wah position (think "Money For Nothing" by Dire Straits) by setting the Wah Control parameter to a fixed value.

Slow filter

Attach the LFO internal controller to the Wah Control parameter in the Wah block to create a slow evolving filter effect.

Solving the thump when engaging the Wah

Engaging the Wah can cause a low frequency thump. This is related to Input impedance.

"The thump isn't the wah, it's the Input Impedance changing. If your preset is set to Auto for the Input Z, when you engage the wah the impedance switches. This causes a slight thump if you are playing since the load on your guitar changes. If you want to avoid this, turn Input Impedance to 1M OHM." source
"Set the Input-Z on the preset to 1M rather than Auto. The reason the Wah engages abruptly is because it switches the input impedance. Setting Input-Z to 1M overrides the impedance switch (and, frankly, sounds better IMO)." source

The above doesn't apply to Fractal Audio processors with a fixed (not adjustable) input impedance.