Although initially invented in response to a request by trumpet player Clyde McCoy, who'd asked the Vox corporation for an electronic device that could simulate the sound of a muted trumpet for use with a keyboard, the wah-wah pedal was quickly appropriated in the late 1960s by rock guitarists. In doing so, they defined both a musical period and instituted an aesthetic, one that, when realized through guitar virtuosos such as Jimi Hendrix and Eddie Hazel of Funkadelic, has been referred to as "psychedelic soul." According to Art Thompson, in an article published in Guitar Player Magazine titled "Wah: The Pedal That Wouldn't Die" (May 1992; my source for the article can be found here), Vox was the first company to have success with the wah-wah pedal. Thompson writes: "Vox's entry into the wah-wah pedal business came about thanks to Brad Plunkett, a twenty five year old engineer at Thomas Organ. Around '66 Plunkett was working on a circuit to replace the 3-position MRB, or voicing switch, with a less expensive potentiometer.... To test the idea, a guitar was plugged in and, as Plunkett describes 'all of a sudden people came running in to see what was making this sound--they just freaked out on it.'" Thompson continues:
Apparently Vox management saw lots of potential in this new gizmo, and it was subsequently introduced as the Clyde McCoy wah-wah pedal.... These early pedals were manufactured in Italy and have a picture of Clyde on the bottom. They were distributed in the U.S. by the Thomas Organ Company.... Vox also offered a non-signature model around this time that simply said "Wah" on the bottom plate; it was also made in Italy.
About the wah-wah pedal's subsequent development, Thompson writes:
The introduction of the Vox Cry Baby pedal around 1968 came about because the U.S. distributor, Thomas Organ, and the European distributor, JMI, both wanted to sell the wah-wah but neither wanted the other to have the same pedal. Vox solved this by slapping the Cry Baby name on the same model for the American market. The story goes that when Vox needed a new name for the pedal, they asked one of their distributors to describe the wah's sound. The response was "it sounds like a baby crying." Also at this time, Vox and Thomas Organ introduced a new model designated V846 that used a Japanese inductor made by TDK instead of the Italian made inductor. Most purists agree that this change degraded the sound of these pedals, but in the informal tests we conducted, our favorite (because of its almost human vocal quality and vomiting sounds) was an excellent sounding V846....The next major change ocurred when Vox came out with the King Wah, the first unit made completely in the United States.... Many of these devices offered extra sounds like fuzz, sirens, surf, tornado, and God knows what else.... As the late '70s approached, the wah effect was becoming unhip, and the number of manufacturers dropped accordingly.
Early Recordings Featuring the wah-wah pedal
Cream - “White Room” Wheels of Fire (1968)
The Jimi Hendrix Experience - “Voodoo Chile (Slight Return)” Electric Ladyland (1968)
The Temptations - “Cloud Nine” Cloud Nine (1968)
Tommy James and the Shondells - “Crimson & Clover” Crimson & Clover (1968)
Sly and the Family Stone - “Sex Machine” Stand! (1969)
Blind Faith - “Presence of the Lord” Blind Faith (1969)
Chicago - “25 or 6 to 4” Chicago II (1970)
Santana - “Samba Pa Ti” Abraxas (1970)
Funkadelic - “Maggot Brain” Maggot Brain (1971)
Isaac Hayes - “Theme From Shaft” Shaft (Soundtrack) (1971)
In 1972, Isaac Hayes' "Theme from Shaft" won an Academy Award for "Best Original Song," thus making it the first rock song featuring a wah-wah pedal to be honored with a major award.