I have a very detailed website on all the Big Muff versions, but I thought I would post simple summary of all the versions with notes about the differences in tone for each.
Version 1 - “TRIANGLE” BIG MUFF (USA 1969) - The tone of the V1 Triangle has been described as the best sounding of all the Big Muffs. It has also been described as one of the most articulate Muffs, with a clarity that many of the later Muffs seemed to lack. However, it should be clearly stated that there is no ‘one’ triangle Big Muff tone. There is more variance in Triangles than any other version due to the wide variety of component values used in the circuit from day to day, and I have never seen two Triangles with exactly the same values. That said, there are some attributes that define a “typical” V1, and I use that term loosely. The mids were very scooped, as in flat or removed, and there was usually a bit more sustain and brightness than most later versions. For that reason many V1 Big Muffs do cut through a band mix very well and are very articulate for leads, and have a nice crunch for power chords and palm muting, whereas many later versions were muddier and bassier. V1s are very similar to the later V2 Ram’s Head Big Muffs, and some will sound identical. V1s have slightly less bottom end than typical V2s based on most examples I have played. The bass and treble of the tone varies quite a bit from one Traingle to another, as does the gain, fuzziness, and clarity on notes. In the extreme ranges you may find some are very dry and fuzzy sounding, some gritty and fat, some thin and gainy, some thick but smooth, et cetera. The wide variety in sound is one reason V1 Big Muffs are so collectible.
Version 2 - “RAM’S HEAD” BIG MUFF (USA circa 1973) - As with the V1 Big Muffs, the bass, treble, gain, and fuzziness of the tone varies slightly from unit to unit due to varying component type and values used in day to day production. I am descibing some typical attributes here, based on dozens of examples I have played or own. The mids were very scooped, as in flat or removed, giving them a nice dark sound. The tone is usually large and aggressive with a nice scooped grit, though some are more smooth sounding. On many examples the sustain seems to be less than most V1 Triangle Big Muffs I have played. They typically have slightly less clarity for leads, and can be difficult to plam mute through certain amps. The the"violet” version would be an exception, as that one has a nice, smooth calrity for leads and chords, and typically less bottom and. Some V2 Big Muffs will sound identical to some V1 Big Muffs. There is more of a mids scoop on most V2s that I have played versus the V1 Muffs, and there is usually a bit more bassy bottom end than a typical V1. That bottom end creates a huge, thunderous sound through a tube amp. The scooped tone makes them easy to get lost in a band mix when playing live with certain amps. Listen to the Animals and The Wall era Pink Floyd albums for examples of solo tones using this pedal, and listen to Dinosaur Jr. for examples of the wall-of-sound use of this pedal.
Version 3 “RED AND BLACK” BIG MUFF (USA circa 1976) - As with the V1 and V2 Big Muffs, the bass, treble, gain, and fuzziness of the tone varies slightly from unit to unit due to varying component type and values used in day to day production, though V3 Muffs are much more consitent than previous versions. Please refer to the V2 description above. The V3 tones were similar to the later V2 tones, since they were essentially the same pedal with a graphics change. Some examples I have owned are bit bassier and less smooth than the V2 Muffs, but a few later V3 models I have played had even more sustain and aggressiveness than typical V2 Muffs.
Version 4 “OP-AMP” BIG MUFF (USA circa 1978) - The four transistors circuit design was radically changed to a new design that used op-amp ICs for this version. This is a great distortion pedal with a big sound and much of the same scooped mids character of the previous transistor versions. I think the transistor versions are more organic and sound better for bluesy solos, but the op-amps are great for crushing, grungier, wall of sound material, heavy distorted rhythm playing, and heavy leads. They have a very deep crunch, flat mids, and superb deep bass control. They are not very good for palm muting. They do not do fuzz quite the same as the transistor versions, nor do they have the same character and organic randomness. The scooped tone makes them easy to get lost in a band mix when playing live with certain amps. Unlike the transistor versions, the tone is very consistent from unit to unit. This is likely the Big Muff circuit heard on most of Smashing Pumpkins’ Siamese Dream album. This is the rarest of the two op-amp Big Muff versions.
Version 5 OP-AMP “TONE BYPASS” BIG MUFF (USA circa 1978) - Practically identical sound to the V4 op-amp Big Muff described above. This version included a ‘tone bypass’ switch. With the bypass switched on it removes the tone circuit, making a huge, peircing. The bypass also allows a flatter EQ that makes it have brighter mid tones. I think the tone in non bypass mode sounds better as the tone control is key to the Big Muff sound, but some people like the by
Version 6 BIG MUFF (USA circa 1980) - The transistor based Big Muff circuit returned. The tone is very similar to the V3 Big Muffs described above. In the examples I have played and owned the tone has more bass and can sound a bit flatter and fuzzier than typical V3 Muffs. Some have the mids slightly more scooped than the V3. All of the V6 Muffs I have played have had more sustain/gain on tap than typical V3 Muffs, but most were also much noisier, had less clarity for leads, and were more fuzzy sounding. The ‘tone bypass’ (not true bypass) switch was kept from the V5 version, which allows you to completely remove the tone section from the circuit, as described in the V5 above.