Offer Details

Electro-Harmonix Op Amp Big Muff PiThe Op Amp Big Muff Pi is a faithful reissue of one of the most sought-after fuzz pedals ever made — the late-1970s V4 (also called IC) Big Muff, which briefly replaced EHX's traditional transistor-based circuit with operational amplifiers and three gain stages instead of four. Original units from that era command sky-high prices on the vintage market, making this reissue an essential piece of gear for players chasing that tone without the collector price tag.The pedal is most famously associated with Billy Corgan of the Smashing Pumpkins, who used the original extensively on the band's landmark 1993 album Siamese Dream — arguably one of the most iconic fuzz tones in rock history. Corgan himself played the reissue and confirmed the magic was still there.What sets this pedal apart from standard transistor-based Big Muffs is its character: more aggressive, grainier, and mid-forward with a biting crunch that cuts through a mix. It excels at wall-of-sound distortion, heavy rhythm work, and thick sustained leads. The Tone Bypass switch removes the tone circuit entirely, delivering a full-range, uncolored blast of fuzz with even more output and presence. When engaged, the tone knob sweeps from dark and woolly to bright and aggressive, with plenty of usable sweet spots in between. It's equally at home in grunge, alternative rock, shoegaze, and doom metal.Key Features:Op-amp based circuit — Uses operational amplifiers instead of transistors for a distinct, aggressive fuzz characterThree gain stages — Differs from the standard four-stage transistor Big Muff, contributing to its unique sonic signatureFaithful reissue of the late-'70s V4/IC Big Muff — Same circuit as the highly collectible originalVolume, Tone, and Sustain (Fuzz) controls — Wide-sweeping tone shaping from dark to brightTone Bypass switch — Removes the tone circuit entirely for maximum output, presence, and aggressionTrue bypass switching — Signal passes clean through the pedal when disengagedCompact die-cast chassis — Pedalboard-friendly footprint9V battery included — Also accepts optional 9VDC power supply (center negative)Approx. 5mA current draw — Easy on pedalboard power suppliesWorks for guitar and bassAll items shipped via UPS Ground where available.