OP Amp Big Muff Pi

The Electro-Harmonix Op-Amp Big Muff Pi is a faithful reissue of the late-1970s Op-Amp (V4/IC) Big Muff, recreating the original circuit in a compact, pedalboard-friendly enclosure. Unlike most Big Muff versions, it uses operational amplifiers instead of transistors and three gain stages rather than four, producing a distinctive high-gain fuzz with a crunchy, aggressive character. Popularized by Billy Corgan on Siamese Dream, it features the classic Volume, Tone, and Sustain controls, plus a Tone Bypass switch that removes the tone circuit for a more direct, full-range fuzz response. Additional features include true bypass switching and 9V battery or DC power operation.