A wah-wah pedal (or just wah pedal) is a type of guitar effects pedal that alters the tone of the signal to create a distinctive effect, mimicking the human voice. The pedal sweeps the peak response of a filter up and down in frequency to create the sound (spectral glide), also known as "the wah effect." The wah-wah effect originated in the 1920s, with trumpet or trombone players finding they could produce an expressive crying tone by moving a mute in the instrument's bell. This was later simulated with electronics for the electric guitar, controlled by movement of the player's foot on a rocking pedal connected to a potentiometer. Wah-wah effects are used when a guitarist is soloing, or creating a "wacka-wacka" funk styled rhythm.
The first wah pedal was created by Brad Plunkett at Warwick Electronics Inc./Thomas Organ Company in November 1966. This pedal is the original prototype made from a transistorized MRB (mid-range boost) potentiometer bread-boarded circuit and the housing of a Vox Continental Organ volume pedal. The concept, however, was not new. Country guitar virtuoso Chet Atkins had used a similar, self-designed device on his late 1950s recordings of "Hot Toddy" and "Slinkey".
The creation of the wah pedal was actually an accident which stemmed from the redesign of the Vox Super Beatle guitar amplifier in 1966. Warwick Electronics Inc./Thomas Organ Company had bought the Vox name due to the brand name's popularity and association with the Beatles. Warwick Electronics Inc. also owned Thomas Organ Company and had assigned Thomas Organ Company to create a new product line called the all-electric Vox Amplifonic Orchestra; the project was headed by musician and bandleader Bill Page. While creating the Vox Amplifonic Orchestra, the Thomas Organ Company needed to re-design the Vox amplifier into a transistorized solid state amplifier, rather than tube, which would be less expensive to manufacture. During the re-design of the USA Vox amplifier, Stan Cuttler, head engineer of Thomas Organ Company, assigned Brad J. Plunkett, a junior electronics engineer, to replace the expensive Jennings 3-position MRB circuit switch with a transistorized solid state MRB circuit.
Plunkett had lifted and bread-boarded a transistorized tone-circuit from the Thomas Organ (an electric solid state transistorized organ) to duplicate the Jenning 3-position circuit. After adjusting and testing the amplifier with an electronic oscillator and oscilloscope, Plunkett connected the output to the speaker and tested the circuit audibly. At that point, several engineers and technical consultants, including Bill Page and Del Casher, noticed the sound effect caused by the circuit. Bill Page insisted on testing this bread-boarded circuit while he played his saxophone through an amplifier. John Glennon, an assistant junior electronics engineer with the Thomas Organ Company, was summoned to bring a volume control pedal which was used in the Vox Continental Organ so that the transistorized MRB potentiometer bread-boarded circuit could be installed in the pedal's housing. After the installation, Bill Page began playing his saxophone through the pedal and had asked Joe Banaron, CEO of Warwick Electronics Inc./Thomas Organ Company, to listen to the effect. At this point the first electric guitar was plugged into the prototype wah pedal by guitarist Del Casher who suggested to Joe Banaron that this was a guitar effects pedal rather than a wind instrument effects pedal. Joe Banaron, being a fan of the big band style of music, was interested in marketing the wah pedal for wind instruments as suggested by Bill Page rather than the electric guitar suggested by Del Casher. After a remark by Del Casher to Joe Banaron regarding the Harmon mute style of trumpet playing in the famous recording of "Sugar Blues" from the 1930s, Joe Banaron decided to market the wah-wah pedal using Clyde McCoy's name for endorsement.
After the initial invention of the wah pedal, the prototype pedal was then modified by Del Casher and Brad Plunkett to better accommodate the harmonic qualities of the electric guitar. However, since Vox had no intention of marketing the wah pedal for electric guitar players, the prototype wah-wah pedal was given to Del Casher for performances at Vox press conferences and film scores for Universal Pictures. The un-modified version of the Vox wah pedal was released to the public in February 1967 with an image of Clyde McCoy on the bottom of the pedal.
Warwick Electronics Inc. assigned Lester L. Kushner, an engineer with the Thomas Organ Company, and Bradley J. Plunkett to create and submit the documentation for the wah-wah pedal patent. The patent was submitted on February 24, 1967 which included technical diagrams of the pedal being connected to a four-stringed "guitar" (as noted from the "Description of the Preferred Embodiment"). Warwick Electronics Inc. was granted US patent 3530224 (foot-controlled continuously variable preference circuit for musical instruments) on September 22, 1970.
Early versions of the Clyde McCoy featured an image of McCoy on the bottom panel, which soon gave way to only his signature. Thomas Organ then wanted the effect branded as their own for the American market, changing it to Cry Baby which was sold in parallel to the Italian Vox V846. Thomas Organ's failure to trademark the Cry Baby name soon led to the market being flooded with Cry Baby imitations from various parts of the world, including Italy, where all of the original Vox and Cry Babys were made. Jen, who had been responsible for the manufacture of Thomas Organ and Vox wah pedals, also made rebranded pedals for companies such as Fender and Gretsch and under their own Jen brand. When Thomas Organ moved production completely to Sepulveda, California and Chicago, Illinois these Italian models continued to be made and are among the more collectible wah pedals today.
Some of the most famous electric guitarists of the day were keen to adopt wah-wah pedal soon after its release. Among the very first recordings released featuring wah-wah pedal were "Tales of Brave Ulysses" by Cream with Eric Clapton on guitar and "Burning of the Midnight Lamp" by Jimi Hendrix Experience, both released in 1967.
Another function of the pedal is to use it to boost certain frequencies by keeping it in a single position, emphasizing the "sweet spot" in the tonal spectrum of an instrument.
The preeminent electric guitar player to use the pedal in this way was Jimi Hendrix, who revolutionized its application by combining a Fender Stratocaster with stacked Marshall Amplifiers (in both static and modulated mode) for lead/rhythm guitar applications unheard of before then. According to Del Casher, Hendrix learned about the pedal from Frank Zappa, another well-known early user. Milestones of this signature guitar and amplifier combination include songs such as "Voodoo Child (Slight Return)" as well as the "Star Spangled Banner" which was played by Hendrix at Woodstock in 1969.
Mick Ronson used a CryBaby for the same purpose while recording The Rise and Fall of Ziggy Stardust and the Spiders from Mars.
An envelope filter or envelope follower is often referred to as an auto-wah.
Another famous style of wah-wah playing is utilizing it for a percussive "wacka-wacka" effect by muting strings and moving the pedal at the same time. This was first heard on a song "Little Miss Lover" (1967) by Jimi Hendrix Experience. One of the most famous uses of this effect is heard on Isaac Hayes's "Theme from Shaft" (1971), Charles Pitts on guitar.
David Gilmour from Pink Floyd plugged in the pedal back to front to create the electronic screams found in the song 'Echoes'. This technique is sometimes called haw haw.
Many bassists have also used the wah-wah effect, for example Michael Henderson on Miles Davis's album On the Corner (1972). Bassist Cliff Burton of Metallica used a Morley Wah pedal (along with a Big Muff Distortion) extensively, including on "(Anesthesia) Pulling Teeth", which is primarily a bass solo recorded for Kill 'Em All (1983), and "The Call of Ktulu" and "For Whom the Bell Tolls", both recorded for Ride the Lightning. Geezer Butler, bassist of Black Sabbath, used it when playing his solo "Bassically", along with the bass line in "N.I.B.". Chris Squire of Yes used a wah-wah pedal on his solo piece "The Fish" on the album Fragile. While wah pedals are less popular as a bass effect, various companies now offer pedals designed specifically for bass guitars.
Melvin Ragin better known by the nickname Wah-wah Watson, was a member of the Motown Records studio band, The Funk Brothers, where he recorded with artists such as The Temptations, The Jackson 5, The Four Tops, Gladys Knight & The Pips, and The Supremes. He played on numerous sessions in the 1970s and 1980s for many top soul, funk and disco acts, including Herbie Hancock.
Keyboardists have also made use of the wah-wah effect both in the studio and during live performances. Garth Hudson famously used a wah-wah pedal on a clavinet in The Band song "Up on Cripple Creek" to emulate a Jaw Harp. Rick Wright of Pink Floyd played a Wurlitzer electric piano through a wah-wah pedal in their song "Money" to give the impression of many consecutive chords being played. Jordan Rudess of Dream Theater made an extensive use of the wah-wah pedal on Dream Theater's album Train of Thought.
Many jazz fusion records feature wind and brass instruments with the effect - Miles Davis's trumpet being a well-known example. Davis first used this technique in 1970 (at concerts documented on Live-Evil and The Cellar Door Sessions) at a time when he also made his keyboard players (Keith Jarrett, Chick Corea) play electric pianos with a wah-wah pedal. Napoleon Murphy Brock played a saxophone amplified through a wah-wah pedal in the Frank Zappa movie The Dub Room Special, as well as on some of Zappa's albums. David Sanborn can be heard playing an alto saxophone modified by a wah-wah pedal on the David Bowie album Young Americans. Noted saxophonist King Curtis was also known to use a wah-wah pedal. Dick Sims, the keyboard player with Eric Clapton in the late 1970s, used a Hammond organ in conjunction with a wah-wah pedal, sat on top of the organ operated by his palm.
The effect is also extensively used with the electric violin. Notable examples are Jerry Goodman with the Mahavishnu Orchestra, and Jean-Luc Ponty, Don "Sugarcane" Harris and Shankar, with Frank Zappa, all usually engaged in long wah-wah violin/guitar duels. Boyd Tinsley of Dave Matthews Band is known to use a wah-wah pedal live.
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