The Wah Wah pedal uses a foot control to control an EQ filter to sweep the frequency spectrum,
producing the typical Wah sound. However, there are limits to the reaction time of the human foot.
So if you want to experience Wah effects that react faster than humanly possible, you need an
Envelope Follower also known as an Auto Wah Pedal.
The Auto Wah pedal uses the volume of the note as it moves from attack to decay to control
the cutoff frequency of a filter – this is the way the Boss AW-3 operates. A variant of this uses a
low frequency oscillator to control the filter and varies the sweep of frequencies with time rather
than the volume of the signal – this is the method found in the Boss AW-2 Auto Wah.
Songs Featuring Auto Wah
Some well known uses of the Auto Wah effect can be found in "Going
Mobile" by The Who, "Industrial Disease" by Dire Straits, and "Mysterious Ways" by U2. Bootsy
Collins commonly uses the Auto Wah on Bass Guitar and Stevie Wonder applied the effect to his
Clavinet on "Higher Ground."
Top Auto Wah Pedals
Here are some Auto Wah Pedals for your consideration:
Boss AW-3 Dynamic Wah
is by far the most popular pedal in the auto-wah category. It combines classic Auto Wah
effects, Dynamic Wah effects, and a Humanizer effect that simulates a human voice producing vowel
sounds. It has separate inputs for Guitar and Bass to optimize the effect for the frequency range.
You can even attach the AW-3 to an optional expression pedal to control the Wah effect with a
traditional foot pedal.
Harmonix Riddle Q Balls Envelope Filter for Guitar
gives you ultimate control over the
filter with an extremely responsive envelope follower fine-tuned for guitar frequencies, resulting
in a classic funk guitar sound. The Riddle Q Balls Envelope filter includes switchable analog
distortion, optional expression pedal control over the Wah filter, selectable Low Pass, Band Pass,
and High Pass filters, and control over filter sweep.