Wah block

The information on this page supplements the official manuals.

Wah: supported by which Fractal Audio products?

• Axe-Fx II: yes.
• AX8: yes.
• FX8: yes.

X/Y switching in the Wah block

• Axe-Fx II: yes.
• AX8: yes.
• FX8: yes.

List of modeled Wah pedals

Current types in the Wah block:

• 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 – modeled after the “Shaft” sound
• Mortal – based on a Morley wah/volume pedal
• VX485 - based on a Vox V845

Pictures of the real pedal equivalents, by MDProd.

Position of the Wah block

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

Thump when engaging the Wah

Fractal Audio:

• (answering a question about hearing a thump when auto-engaging a wah): "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 AX8's Input Impedance is fixed at 1 MOhm (not adjustable).

Parameters in the Wah block

Tracking

Fractal Audio:
"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

Fractal Audio:
"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

Coil Bias

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

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

The Low Cut Freq parameter sets the highpass filter due to the input coupling capacitor.

Wah output level

When changing the Wah type, its Level is also adjusted automatically because the output of the models has been matched to the original pedals (firmware Quatum 6 and later). source

Fractal Audio:
"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

Auto-engage the Wah

Just like an optical wah pedal, you can engage the Wah automatically when moving the pedal. This is especially handy when using a spring-loaded pedal. To accomplish this, set Auto-Engage in the modifier menu to either a speed-controlled or position-controlled setting.

If you want the Wah to be bypassed automatically at toe-down position (simulating a virtual toe switch), instead of heel-down, set OFF VAL in the modifier menu to 95%.

Special Wah effects

Seek Wah

The Seek Wah is a pedal by ZVEX, which uses a sequenced filter pattern. For an equivalent effect, try the Random Wah factory preset in the Axe-Fx II. For a more pronounced effect, add a Formant filter, attached to the same controller.

Auto Wah

Read this: Envelope filter.

More information

• Decreasing the MAX FREQ value often helps to make a high gain wah tone cut better through the mix.
• Copying frequency range settings from manufacturer's manuals helps emulating specific wah pedals.