14   The Twin-T Phaser/Wah

Even if you have no idea what a wah-wah pedal is, you know the sound. Wah-wahs are responsible for the crying, voice-like articulation in countless rock classics—Jimi Hendrix’s “Voodoo Child” is a great example—as well as the funky-see funky-do wakka-chikka-wakka rhythm guitar in tunes like Isaac Hayes’s Shaft theme. The technical name for this effect is spectral glide, which means the “modification of the vowel quality of a tone.” In this case, the modification emphasizes the waaahs, wooowwwws, and aooows. Control the spectral glide with a foot pedal, and you have a wah-wah pedal. Automate it with an LFO (like the Universal LFO in Project 13), and you have a phaser effect. Tweak it with a plain old knob, and you

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