Electro Harmonix Op Amp Big Muff Pedal, EHXNOPA

The Electro Harmonix Op Amp Big Muff is a reissue of the classic IC or V4 pedal from 1978 that has appeared on many recordings since its release. The new and improved Op Amp Big Muff features several modifications for the modern player, including a die-cast enclosure and true bypass switching. What makes this particular Muff so special is the design incorporates op-amps to produce the distortion rather than transistors; this gives the sound a coarser edge perhaps closer to the Russian Big Muffs' tone. Easy-to-use controls for Volume, Sustain and Tone make dialling in your perfect fuzz tone easy, and the LED provides easy visibility in dark environments. This faithful recreation of a beloved classic is perfect for Smashing Pumpkins' enthusiasts and fuzz connoisseurs alike; with a tone this thick, there's something for everyone.

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Recreated With Modern Improvements

The sound of the EHX Op-Amp Big Muff will be instantly recognisable to many, whether you initially realise it or not. This new and improved version builds on the success of its predecessor along with up-to-date modifications such as a compact, die-cast enclosure, and true bypass switching. Cleaner operation with all the character and tone that made the original so revered.


Despite its compact size and simple layout, players will be blown away by the sheer power that the Op Amp Big Muff produces. Control options include Volume, Sustain and Tone, along with a sturdy footswitch for hands-free operation. True bypass switching is also included and ensures a clean signal when the pedal is inactive.


The Electro Harmonix Op Amp Big Muff's circuitry relies on op-amps rather than traditional transistors, along with three gain stages instead of four, to produce its iconic sound. This simplicity was key to making the original so unique and special and that trend is continued with the reissue.


  • A faithful reissue of the original classic from 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 structure
  • Easy-to-use interface
  • Ships with a 9Volt battery, also accepts an optional EHX9.6DC-200 AC Adapter


  • Current draw: 5mA @ 9VDC
  • Dimensions: 70 (W) x 115 (H) x 54 (D)mm
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Brand Electro Harmonix
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