Electro Harmonix Op-Amp Big Muff Guitar Effects Pedal

Product ID: 205204
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  • Awesome reissue of the classic era Big Muff circa 1978
  • Pedal responsible for generating Smashing Pumpkins' "Siamese Dream" wall of saturated noise
  • Solid and durable tour-ready build quality
  • Diminuitive form allows it to slot into any pedalboard setup
  • Produces covetous fat, saturated, big fuzz tones
  • Intuitive control layout makes it easy to dial in your tone
  • True bypass switching for maximum signal integrity in bypass mode
  • Includes 9-volt battery to get your playing immediately
  • Optional Electro Harmonix 9.6DC-200 power supply available


The Electro Harmonix Op-Amp Big Muff Guitar Effects Pedal resurrects the classic era rendition of the pedal that aided Billy Corgan and James Iha in creating a generation-defining wall of sound on their seminal release, "Siamese Dream". Without it, classics such as "Cherub Rock" and "Today" just wouldn't be the same. Following the success of that album, the pedal went on to be coveted by ardent collectors, which saw its price skyrocket. Mike Matthews - Electro Harmonix founder - decided to step in, and thus the Op-Amp Big Muff has been released to provide us mere mortals with rock god-like tones at an affordable price.

Classic Big Muff tones

The original Big Muff of the 1970s was designed taking inspiration from players and pedals of the time (in particular Jimi Hendrix). The Op-Amp Big Muff borrows the spirit of the original design, but differs from the traditional transistor design, instead using operational amplifiers (op-amps) to produce that rich, sustaining distortion. With three-gain stages at its heart, this beauty is capable of producing an enveloping tsunami of sound, and is perfect for those who want to create unique sonic soundscapes.

Simple control layout

Across the front panel you'll find a trio of controls knobs that can be used to shape your output: Tone (with an On/Off switch), Sustain, and Volume. The Volume control sets the output level of your pedal, allowing you to decide what kind of impact it makes when you hit the footswitch. The Tone control provides a range of sounds from a high treble to a resounding low-end. The corresponding Tone On/Off switch, allows the Tone control to be removed from the circuit, without affecting the Volume level. The Sustain pot adjusts the amount of sustain and saturation introduced to your tone, from slight gristle to sweeping wall of sound.

Thanks to Electro Harmonix' True Bypass design, your tone remains unblemished when it is inactive.

Pedalboard-friendly design

The original Big Muff pedal was larger in size, which many guitarists found occupied more space on their pedalboards than they would have preferred. However, the Op-Amp Big Muff is significantly smaller, and a much more pedalboard-friendly design that is perfect for integrating into any setup with ease.

The Electro Harmonix Op-Amp Big Muff Guitar Effects Pedal is supplied with a 9V battery to get you powered up and playing immediately, and can also be powered by an optional EHX 9.6DC AC adapter, making it a truly portable pedal.

Manufacturer Electro Harmonix
ModelOp-Amp Big Muff Guitar Effects Pedal
Dimensions (H x W x D) 54 x 70 x 115 mm
Effect Type Distortion
Controls Volume, Tone, Sustain
Included Accessories 9-Volt Battery
Optional Accessories EHX 9.6DC-200 AC Adapter
Posted on 18/02/2019 by Sometimes the comment "it does what it says on this tin" is used to make up for a lacklustre device or not having much to say. This does (or rather the box, where it tells you it is your piece of pumpkin pie), if you do not develop a sudden urge to play Cherub Rock you probably don't deserve to buy it. Crack the guitar hard into the pedal, crank the pedal hard into the amp and prepare for Armageddon. My 7 year-old asked if he could use a "bad word" to describe it. Try it on something detuned, or a 7 string and OMFG...

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