Hey everyone, I’ll occasionally (maybe monthly, maybe weekly, maybe whenever the hell I feel like it) be posting my Big Muffs and their circuits for (Big) Muff Mondays.

Since I got this one out so late some of you may be reading this on Tube Screamer Tuesday…this week features a 1979 Red & Black Tone Bypass with an EH-3003 circuit. The Operational Amplifier Muff is the first by Electro-Harmonix to feature a “tone bypass” switch. The TB switch bypasses the tone potentiometer making the pedal similar to early fuzz units like Maestros, the two-knob Guild Foxey Lady, and Axis. Those pedals don’t all necessarily sound the same, I’m more just referencing that they also bypass the tone section. This era of Big Muff is often referred to as a Version 3 (v3), but as I mentioned in earlier blogs, calling each model a “version” makes things quite convoluted as there were many variations on the circuits (especially Triangles and Ram’s Head units). To be more specific, it is a 1979 Red & Black Tone Bypass. It’s a mouthful, trust me I know, but it beats just calling it “version 3.”

The enclosure is the exact same as the tone bypass op amp (v5) and 80’s (v6) showing “Tone Bypass,” “AC,” “Amplifier,” “Input,” “Volume,” “Tone,” and “Sustain printed on the face. They usually had identical circuits and components with either 2N5088 or MPSA18 transistors amongst themselves but different component values than v1 and v2 Red & Black ’77 Muffs. In fact they were much closer to late ’76 Ram’s Head circuits and the v6 (nearly identical) to follow. That said, I’d describe the sound as a ’76 Ram’s Head (that has 5088s), with the tone bypass feature, and a ton more gain.

The pots, knobs, and battery snap are unoriginal and were replaced by a previous owner. The pots were replaced with three 100k Alphas and the battery snap was replaced with a generic one. The only other non-original design here is that at some point the hot wire from the power jack was disconnected from the circuit until recently. Two globs of solder, a good set of spectacles, some patience, and this Muff is ready to rock again. I’ll briefly go over some of the components and values found below: 2n5088 transistors, blue silicon diodes, carbon film resistors, polyester .1uF and .01uF capacitors, polarized electrolytic 1uF and 3uF caps, ceramic 470pF and .004uF caps, and 100k linear tape potentiometers. Sounds like a bunch of stuff crammed in there right? Well if you look at the board below it really couldn’t be any simpler.

From 1977-1980 there were a few Big Muffs available and it can be quite confusing to decipher which is which and how they might suit your style. The first Red & Black enclosure Big Muff was introduced in 1977. Most of the first versions of the pedal are identical to late Ram’s Heads but placed inside the new enclosure. While it wasn’t the biggest hit at first, it became the iconic look of a Muff and around that time musicians like Frank Zappa turned to them. Not long after that the release of the 1977 Op Amp Big Muff (v4) was introduced, in 1977. This version did not include the tone bypass feature and using operational amplifiers along with some value tweaking gave these pedals a very different than previous pedals. Think Siamese Dream by The Smashing Pumpkins.

1977 Red & Black (Unaligned Pots, No Tone Bypass) SOURCE

In 1978, the second op amp unit with tone bypass (v5) was introduced. Lastly, what most folks call the Version 6 (v6) or “80’s Muffs” hit the floor in 1979. These all had very similar circuits with only the EH-1322 and EH-3034 schematics. Even then, they had very little variation from unit to unit sound-wise. These are however unique by enclosure because of how many color variations were available.

1978 Op Amp (Aligned Pots w/ Tone Bypass) SOURCE

In conclusion, it was very possible to walk into a music store and see three different ’77 transistor Red & Black (no power, w/ power, and w/ tone bypass), the ’77 Op Amp, the ’78 Op Amp, and back to the transistor design with the 80’s Muffs. Some shops may have even still had Triangles and Ram’s Head units in the shop. Although by the late ’70s Electro-Harmonix was quite popular and word got around that David Gilmour used a Ram’s Head on Dark Side of the Moon and that Santana used a Triangle.

The slideshow below shows all images of circuit, components, and enclosure.