Electro-Harmonix Op Amp Big Muff Pi Overdrive Pedal

Stomp on the EHX Op Amp Big Muff Pi to induce a Siamese Dream of crunchy fuzz tones. This unique Muff features a tone bypass switch for unfiltered goodness.

With original late-'70s Op-Amp Big Muffs selling for exorbitant prices, Mike Matthews decided to take the power to the people and reissue the classic pedal at a price that players could afford! The circuitry of the Electro-Harmonix Op Amp Big Muff overdrive pedal, sometimes also referred to as the IC or V4 Big Muff, has been faithfully re-created while several practical enhancements have been added including a compact, die-cast chassis and true bypass switching.

"The Op-Amp Big Muff was popularized by the brilliant Billy Corgan who first used it on the Smashing Pumpkins' epic 1993 album Siamese Dream. After he was videotaped playing and talking about the reissue, Billy stated: 'The magic's still in the box, I can still get what I'm looking for!'" - Mike Matthews

The pedal relies on op-amps rather than transistors and three gain stages rather than four, to create its signature sound. It's a sound that's been described by noted Big Muff collector and historian, Kit Rae, as "a huge, crushing Big Muff sound with more crunch" great for grungy, wall-of-sound distortion, heavy rhythm playing and heavy leads.


- A faithful reissue of the original classic circa 1978
- Iconic sound and vibe that's coveted by guitarists
- Controls for Tone, Sustain and Volume, plus a Tone Bypass switch
- True bypass switching for maximum signal integrity in bypass mode
- Rugged, compact, die-cast package, pedalboard-friendly
WARNING: Cancer and Reproductive Harm - www.p65Warnings.ca.gov.

Dimensions and Weight in Packaging
Base Item
Shipping Weight: 0.5 lbs
Shipping Dimensions: 6 x 4 x 3 in
Manufacturer Part Number (MPN): OPAMPBM

For support or warranty questions, please contact the manufacturer:
Phone: 718-937-8300

Reviewers gave this product an overall rating of 5 out of 5 stars. (3 ratings)
Submitted April 10, 2018 by chad t in turlock, CA

"op amp wins!!"

Overall: 5 out of 5 stars
(see rating details)
Verified Customer zZounds has verified that this reviewer made a purchase from us.
a great little pedal loaded with a huge sound features: tone vol and sustain (gain) knobs plus a switch to bypass the tone stack and get a really gnarly sound quality: built like all EHX pedals, super stout switch feels nice sound: big and dirty. this pedal sounds beefier than my tone wicker big muff pi. the sound is dirty and kind of noisy but it responds to your playing. ease of use: only 3 knobs and a single switch, if you feel like you need more knobs to fiddle with try the JHS pumpkin patch modded pedal value:this pedal is pretty cheap but sounds great and is built like a tank the wow factor: yeah its there, it did what i expected out of the box, just cranked the sustain and went to town

Musical Background:

long time guitar player

Musical Style:

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