Op-Amp Big Muff Pi

Product Information

Circuit-wise, it’s pretty much the same as the Fuzz Face Mini, though MXR describes it as a “ mini version of their 108 Classic Fuzz“ (which, if you read the description, is a standard housed Fuzz Face…. so it’s the same?). The Emitter Resistance: Adding an emitter resistance R 22to a common emitter amp, also known as Emitter Degeneration, makes the voltage gain less dependant from BJT parameters, and therefore less vulnerable to temperature and bias current changes. The stability characteristics of the circuit are thus improved at the expense of a reduction in gain. Shown above - Billy Corgan's V4 Big Muff shown with his exact settings used for the Smashing Pumpkin's Arising tour in 1999

As the names of both pedals suggest, Jimi Hendrix's sound was a major inspiration for those pedals, and for their successor: the Big Muff! According to Electro-Harmonix founder Mike Matthews, Hendrix actually had a Big Muff and was impressed enough to useit on some sessions. The explanation is its low input impedance. What this means in practice is that it's a very dynamic pedal, hugely sensitive to the input from the guitar. It can clean up using the guitar's volume knob, or indeed be pushed into breakup if set up to leave part of a turn remaining. It's this quality that is particularly appealing to blues players. To me the Big Muff pedal changed the entire course of the album (Siamese Dream). That album is a classic album because of a certain way of thinking with this pedal. So when people say “why was this a classic album” and they wanna talk about pain and drugs and Jimmy (drummer Jimmy Chamberlain), the Big Muff is just as important" - Billy Corgan from a 2005 Netphoria interviewFor this reissue, Electro Harmonix have gone all-out in delivering the same kind of tones that the original Op-Amp Big Muff Pi was famed for. Relying on op-amps rather than transistors, and three gain stages rather than four, the new EHX Op-Amp Big Muff Pi can produce a huge, crushing Big Muff sound with more crunch, that's great for heavy rhythm playing and heavy leads. Pumpkin Pi The Ram's Head Big Muff and Triangle Muff are often associated with Dinosaur Jr. However, J. Mascis has used a lot of different fuzz boxes over the years. That, plus very tight control over their live and studio tone, means that assuming their tone is accessible with just a Big Muff is a mistake. With a C 10of 470pF and depending on the internal BJT capacitance, low pass filter cut-off frequency is around 1.2KHz. This operation occurs just before the distortion stage; clipping a low-passed signal usually sounds better, smoother and less harsh.

We found a secret weapon on that record,” says Vig. “A little preamp in a pedal steel guitar. It wasn’t built for a loud guitar. It was built for a low output on a pedal steel, so it had this super high-end white noise gain that gave the guitar this sonic jet sound.” - Butch Vig, producer of Siamese Dream

CLONES OR SIMILAR PEDALS - E-H released a reissie Op Amp Big Muff in the nano sized enclosure in 2017. The Deluxe Big Muffs from the late 1970s also used a nearly identical circuit to the V4, as well as some of the Little Big Muff pedals Electro-Harmonic made in the same time period. Later replicas are the Euthymia ICBM, Stomp Under Foot Op-Amp Fuzz. See DiscoFreq's Effects Database for a thorough listing of all the Big Muff clones and variants throughout the years. Intentionally simple, this muff evolution intends to provide the player with plenty of tonal options without an excessive number of controls. Inspired by the Ram’s Head Muff, the T4 is an attempt to “perfect” that sound with better components, a more present mid-range, and a sweeter-sounding tone control. The output volume is also increased to push your amp to the edge of breakup.

Many inspiring guitarists use this stompbox, giving to the Big Muff Pi a leading role in the hard-driving music signature: The components selected for the design are very generic and easy to find: just high gain NPN transistors, simple silicon diodes and standard resistors, caps and three 100K linear pots. Avoiding exotic parts and making the circuit ready for mass production and a shortage of suppliers.

All in all, the key here is that germanium transistors will provide a lower gain and a more vintage tone to silicon. Germanium pedals also tend to be more expensive due to the fact that germanium transistors are less common and more unreliable, so they require a little bit more circuit testing and design to build.

The Big Muff is an iconic pedal.Many versions of this classic stompbox have been created since its introduction in the 70s, and Billy Corgan of The Smashing Pumpkins is arguably the most-renowned user of the Electro Harmonix Big Muff.Pioneering the huge, engulfing "wall of fuzz" sound that definedthe groundbreaking Siamese Dreamalbum in the mid-90s, Corgan relied on a particular iteration of the circuit to attain that massive sound - the V4. GRAPHICS - The box, knobs, and graphics were identical to the second edition Version 3 BIG MUFF, and these V4 Muffs are often confused with the V3. The only way to tell is to look at the circuit board for the two distinct op-amp chips, or to turn the control knobs to see which way the pots are mounted, as illustrated below. V3s all have the pre 1978 configuration, and V4s have the post 1978 configuration.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. The circuitry differences deliver a slightly flatter midrange compared to transistor versions. This, along with the slightly reduced gain levels, deliver the grungier sound these Muffs are known for. Features CIRCUIT - The circuit uses normal through-hole style capacitors and diodes. All resistors are small surface-mount type."ICBM" is printed on the circuit board, a reference the Euthmia ICBM, one of the first clones of the op-amp Big Muff that helped bring about a new interest for this somewhat underappreciated version of the circuit. 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.” Specifications Shown above - V5 op-amp EH-1322 circuit boards with pots dated 1978 and tone bypass cap/resistor components mounted on the trace side. The V5 op-amp EH-1322 circuit number later changed to EH-3003B, but still with tone bypass cap/resistor components mounted on the trace side. There have been so many different variations on the Big Muff Pi circuit through the years you could devote an entire article just to talking about them.