The Effects
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TRACK -
Sets the ‘Q’ tracking of the filter. As the frequency is increased the resonance will be
decreased by an amount proportional to this value. If this is zero the resonance of the filter will be
constant at all frequencies. Classic wah pedals usually have a resonance that decreases with
frequency due to design limitations. This control can be used to mimic those pedals.
FREQ -
Sets the frequency of the filter relative to the minimum and maximum frequencies.
Normally you would attach this to a controller. Attach it to an external controller (such as pedal) for
classic wah or attach it to an LFO or Envelope for autowah or dynamic wah.
Formant Filter
The wah was originally intended to mimic the sound of the human voice but obviously falls a little
short. A formant filter is an extension of the wah principle but operates on the concept of formants.
Formants are resonances in instruments, cabinets, and, in this case, the human vocal tract that give
sounds their character. The human vocal tract generates a handful of formants that produce the
vowel sounds we recognize. For example the vowel sound "eee" can be reproduced with a bank of
narrow bandpass filters with various frequencies and amplitudes. The Axe-Fx Formant Filter allows
"talk-box" effects without the fuss and muss of the real thing.
The Format Filter morphs between three vowel sounds: start, mid and end. The
CTRL
knob then
controls the morphing between these sounds. For example, we can program the Formant Filter to
go "ooo - eee - aaahh" as a pedal is moved. The start vowel is generated with the
CTRL
knob
counter-clockwise, the end vowel is generated with the knob fully clockwise and the mid vowel is
generated with the knob at 12:00. The sound gradually changes from one vowel to the next between
positions.
The Formant Filter usually sounds best when placed after distortion although there are no hard and
fast rules.
Parameters
START -
Sets the start vowel sound.
