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Professor’s Notes

The Op-Amp Big Muff Pi recreates the late-’70s “IC” Muff circuit made famous by Billy Corgan on Siamese Dream. It’s punchier and more aggressive than transistor-based Muffs, offering a distinctive fuzz character that stands out in a mix — all in a compact, affordable package.

Description

The Electro-Harmonix Op-Amp Big Muff Pi Distortion/Sustainer is a faithful reissue of the original late-1970s op-amp-driven Big Muff, long prized by collectors for its unique sound. Unlike traditional transistor-based Muffs, the op-amp design delivers:

• More attack and clarity in the midrange.
• Tighter low end with less “wooliness.”
• Aggressive sustain that cuts through dense mixes.

Controls for Volume, Tone, and Sustain keep operation simple, while a Tone bypass switch allows players to lift the tone circuit entirely for extra raw output and presence.

Compared to vintage units — now scarce and expensive — the reissue brings the same iconic fuzz at a fraction of the cost, with modern reliability and a pedalboard-friendly size. Whether chasing Billy Corgan’s Pumpkins-era sound or just looking for a more articulate Muff, the Op-Amp Big Muff Pi delivers.

Specifications

• Type: Analog fuzz/distortion pedal (op-amp circuit)
• Controls: Volume, Tone, Sustain, Tone Bypass switch
• Bypass: True Bypass
• Audio: Mono input/output
• Power: 9V battery included or optional 9VDC power supply (not included)
• Current Draw: ~3mA
• Dimensions: 4.75" x 4" x 2.25"

What’s Included

• Electro-Harmonix Op-Amp Big Muff Pi pedal
• 9V battery (installed)
• Original packaging