Wah block

Wah: supported by which Fractal Audio products

• Axe-Fx III: 2x.
• Axe-Fx II: 2x.
• AX8: 1x.
• FX8: 2x.

Wah: X/Y switching or channels

• Axe-Fx III: 4 channels.
• Axe-Fx II: yes.
• AX8: yes.
• FX8: yes.

List of modeled wah pedals

• 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 pedals, 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.

Engaging the Wah can cause a thump

"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).

Explanation of parameters in the Wah block

Tracking

"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

"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 Max Freq helps to make a high gain wah tone cut better through the mix.

Coil 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

Output Level

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

Auto-Engage the Wah

Like an optical wah pedal, you can engage the Wah block automatically when moving the expression 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%.

Create special wah effects

Seek Wah

The Seek Wah is a pedal by ZVEX that uses a sequenced filter pattern. For an equivalent effect, assign the Sequencer (internal controller) to the Control parameter. For a more pronounced effect, add a Formant filter, attached to the same controller.

Auto Wah

Read this: Envelope filter.

Fixed wah

Simulate a fixed wah position (i.e. Money For Nothing by Dire Straits) by setting Control to a specific fixed value.

Slow filter

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

Using an expression pedal as a wah

More information about expression pedals.

More Wah block tips

• Copying frequency range settings from manufacturer's manuals helps emulating specific wah pedals.
• Forum member Leon Todd emulates Dunlop's Petrucci and Cantrell was pedals.