wah pedal
A foot-operated effects pedal that rocks back and forth to sweep a bandpass filter, creating a vocal "wah-wah" sound on electric guitar.
In Depth
The wah pedal was invented in 1966, originally as a trumpet effect, but found its true home with electric guitarists. The foot-controlled rocker shifts the center frequency of a bandpass filter, emphasizing different harmonic frequencies as it sweeps — producing a sound reminiscent of a human voice saying "wah." The most famous model is the Dunlop Cry Baby, descended from the original Thomas Organ design.
Jimi Hendrix was among the first guitarists to exploit the wah pedal creatively, using it throughout "Voodoo Child (Slight Return)." Shaft's iconic theme by Isaac Hayes made the wah-guitar synonymous with 1970s funk and blaxploitation cinema. In subsequent decades, it became essential to funk, soul, and rock guitar styles. Players like Kirk Hammett, Tom Morello, and John Frusciante each developed distinctive approaches to the effect.
The wah pedal was originally designed to mimic a trumpet with a Harmon mute — but guitarists adopted it so enthusiastically that its brass origins were quickly forgotten.