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Electro-Harmonix Op Amp Big Muff Pi

What could be any better than a big muff pi?


by Chris Loeffler



Electro-Harmonix recently made a lot of folks happy when they re-released the Big Muff circuit that helped define 90’s alternative music as the Electro-Harmonix Green Russian Big Muff Pi. They’re at again, undoubtedly eyeing the business smaller effects companies have garnered with their costlier recreations of long retired circuits, and recently released the Electro-Harmonix Op-Amp Big Muff Pi.


The Electro-Harmonix Op-Amp Big Muff Pi features the same three Volume, Tone, and Sustain controls that their standard Big muff brethern include and adds a tone bypass switch similar to the one found in the Big Muff Pi with Tone Wicker. The Op-Amp Big Muff Pi runs on standard 9V DC negative power and was designed and assembled in New York. 


What You Need to Know


The Electro-Harmonix Op-Amp Big Muff recreates the V4 Big Muff circuit, which was the only version to incorporate op-amp ICs in place of the traditional four transistor clipping sections used before and after this version. At the time, many players preferred the organic tone of the transistor circuit as they are undeniably closer in behavior and tone to a traditional fuzz, but some players loved the heavier, more aggressive nature of the ICs. Made famous by Billy Corgan on the Smashing Pumpkins albums Gish and Siamese Dream in the early 90’s, the original op-amp versions had long since been retired and players were left scratching their heads and trying to figure out why their Big Muff Pi pedals couldn’t exactly cop the aggressive, wall of sound fuzz they heard on those records.


The Electro-Harmonix Op-Amp Big Muff Pi brings the ICs back, and the result is a more punishing, all-encompassing distortion that layers beautifully. The Volume control goes from “is this on?” to amp shaking levels of volume, and the Tone knob rolls back the highs and slightly boosts the lows, depending on where it is set. While Big Muff circuits have always been somewhat woofy in the low end, V4 was especially known for its bass-heavy tone. In the case of the review unit, I found it to have more bass than a standard NYC Big muff Pi, but not necessarily more than the aforementioned (and reviewed) Green Russian.


The Sustain control dials in the distortion, with incremental increases in gain and sustain. The distortion is heavy, and there aren’t low gain sounds to be pulled from the lower regions of the dial, just thicker fuzz that goes from gated to almost playing itself at full tilt. Because of the circuit’s anemic mid-range, the Op-Amp Big Muff Pi soars as a rhythm tone but struggles to cut through as a lead without the help of a more mid-focused overdrive or EQ placed after it. 


The Tone switch entirely bypasses the tone section of the effect, resulting in an even more brash and unleashed distortion that sounds more aggressive and fuller. The high-end sizzle is backed off and the decay has a more amp-like feel to it with less gating. While the filtering involved with the Tone control is useful for dialing the fuzz into the mix, I much preferred the urgency of the effect with the Tone bypassed for playing at home or in settings where the nuance can be heard.


Like all Big Muff Pi circuits, the scooped tone means the pedal pairs best with a Brittish-voiced amp like a Marshall JCM800. When played into a ’77 Fender Pro Reverb, also famously lacking in mids, the two compounded each other’s weaknesses in this frequency range.


I didn’t have an original EHX V4 Big Muff Pi to run head-to-head against the reissue, but I have had the pleasure of playing them in the past and I can say the tones were similar, if not identical. I did put it against the Blakemore Effects DreamsICle fuzz, which was derived from the V4 circuit and seemed a fair sonic touch point. The DreamsICle follows the same circuit, with the only difference being the tone bypass switch has been replaced with a footswitch. To my ears, the DreamsICle was warmer and slightly smoother than the Op-Amp Big Muff with the tone stack engaged, with a slightly more pronounced lower-midrange and thicker bass frequencies. When both bypassed the tone control, the Op-Amp Big Muff shined with more presence, girth, and mids along with a tighter upper-midrange. 




The scooped-mid tone of the Op-Amp Big Muff Pi doesn’t gel well with traditional Fender-style amps.




If you’re looking at this pedal, you likely already know what you’re after… thick, slightly-scooped distortion/fuzz that dominates the upper and lower frequency ranges, The Electro-Harmonix Op-Amp Big Muff does this in spades, although it might take some tweaking with the Tone control (or not) to find its place in your sound. At a such an affordable price, it’s easy to justify the cost for a different flavor of fuzz to build your sonic wall.   -HC-




Electro-Harmonix Op-Amp Big Muff Pi Product Page


Buy the Electro-Harmonix Op-Amp Big Muff Pi at Full Compass (MRSP $107.50, Street $80.60)







Chris Loeffler is a multi-instrumentalist and the Content Strategist of Harmony Central. In addition to his ten years experience as an online guitar merchandiser, marketing strategist, and community director he has worked as an international exporter, website consultant and brand manager. When he’s not working he can be found playing music, geeking out on guitar pedals and amps, and brewing tasty beer. 



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