It’s been a minute, but I’m selling my Electro-Harmonix Op-Amp Big Muff. Therefore, a review seemed like a good idea to help it along.
- Background
- Electro-Harmonix Op-Amp Big Muff: tech specs
- Construction
- Electro-Harmonix Op-Amp Big Muff: tones
- Electro-Harmonix Op-Amp Big Muff: demo
- Conclusion

Background
I mentioned elsewhere that I loved Billy Corgan’s guitar sound. So, when Electro-Harmonix announced the Op-Amp Big Muff as a replica of Billy’s original, I was getting one. Although I’d never owned a fuzz pedal before, I was in on this. When it was released, I visited Reverb every couple of days until a used one showed up.
Electro-Harmonix Op-Amp Big Muff: tech specs
| Construction material | Metal enclosure, plastic knobs, standard metal footswitch |
| Voltage | Your standard 9 |
| Power | Standard square 9V battery, or standard “BOSS” connection from the mains |
| Controls | Volume, tone, sustain |
| Any other cool stuff? | SOUND LIKE THE SMASHING PUMPKINS! |


Construction
It’s a very solid construction. While, look, it’s a very standard pedal style – die-cast enclosure with plastic knobs – there’s a solid weightiness to it. Would it win in a fight against a BOSS pedal? No. But it would go a couple of rounds.
There’s no wiggle room with the knobs or power input. The enclosure is as flush as you’d expect from a well-established pedal manufacturer.
Electro-Harmonix Op-Amp Big Muff: tones
In addition to sounding like 90s alternative rock, the main thing I noted about the Op-Amp Big Muff is how damn loud it is. Of course, that could be the settings I used, BUT…when I tried a clone of it, it definitely wasn’t as loud at the same settings.
You’ll hear it in the demo in the next section, but the Op-Amp Big Muff sounds best with power chords and soloing. For open chords, it’s muddy as hell, and you can barely distinguish one chord from another.
It definitely chugs and squeals, and that’s a great place for a guitar sound to be. As well as chugging and squealing, it’s a wall of filth.
And the main weakness of this review is that I didn’t check it for anything else, because I’m speaking to the most likely audience here.
Electro-Harmonix Op-Amp Big Muff: demo
In order to demo the pedal I recorded power chords, open chords, barre chords, and soloing. I alternated between the “dry” amp sound and the engaged pedal so you can hear them next to each other, and get a better feel for the impact the pedal has.
Because Billy Corgan’s signature Strat had a Chopper in the middle position, that’s what I have on the RF40. Therefore, for a pedal that I think most prospective customers are looking to sound like Billy Corgan, it made sense to focus the demo on that.
However, always remember that online demos are mostly pointless.
Here’s the gear I used to put this demo together.
- Dell 3100 Chromebook
- M-Audio M-Track Duo audio interface
- TC Electronic Ampworx DC30
- Beyerdynamic DT-240 Pro headphones (discontinued)
- RF40 custom partscaster
- Pig Hog instrument cable
- Fender Ombre instrument cable
- Ernie Ball Regular Slinky guitar strings
- Dunlop Gator Grip 1.14mm picks
- Mission Engineering 529i rechargeable pedal power supply
Conclusion
In summary, it’s an absurdly simple pedal. I can’t believe there aren’t more such pedal on the market.
| Pros | Cons |
| Tone! It roars and chugs and squeals | Honestly, none for me. I’m not enough of a fuzz fuss-pot. Even if this doesn’t do what you like, it’s not like there aren’t 108 million other fuzz options. |
| Price. This is not an expensive pedal. There are cheaper, sure, but all in, this is exactly the right price | |
| Construction It’s perfectly solidly built |
You probably landed here because you’re thinking about buying an one. Buy mine!
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