The Electro Harmonix Big Muff is one of the most legendary overdrive pedals ever invented.
I guess, almost every guitarist used this pedal at least once in his career.
The most famous are David Gilmour, Billy Corgan, Jack White, J. Mascis and John Frusciante.
In the 1970s Mike Matthews and Robert Myer invented the Big Muff with the aim of creating a pedal with very much sustain.
Based on the circuit of the fuzz pedals which were pretty famous in those days, the wiring of the Big Muff has been supplemented by several cascaded gain stages and a tone control.
The circuit resembles the circuit of an amplifier with several gain stages.
The silicon transistors made the Big Muff more reliable than many other fuzz pedals.
Besides, it used diode clipping.
Specifically filtering intended to eliminate the fuzz-typical sharpness, so the pedal produced the legendary warm and unique distortion/fuzz tone.
The Big Muff has been produced in a countless number of different versions.
The most famous are the Triangle, the Rams Head and the Russian Big Muff.
But even these versions varied a lot – if you are interested on this topic, I would like to recommend this page.
Occasionally you get the feeling, that the reason for the alteration of the circuit was not to generate a certain variation of the sound but the availability of cheap and most prevalent components.
One interesting example: the resistor of the tone stack in each version varies from 33K to 39K to 20K or 22K.
In my honest opinion: they used the resistors that have been available.
This causes in fact, that every Big Muff sounds a bit different.
If you are willing to get one, it is worth it, to try out diverse Big Muffs and chose the one you like best.
The Big Muff can be modified pretty easily.
To me, the tone bypass mod is quite interesting. Recent models of the Big Muff offered a switch for this option by default.
By removing the tone circuit, the volume increases and there will be a bit more treble in the sound.
Regarding the recent standard version of the Big Muff, this could be quite interesting because, by this, its sound gets more close to the sound of the Triangle.
And of course, it is possible to experiment with the clipping diodes.
By changing the diodes, you can variate the compression and the distortion.
Removing the clipping diodes completely will lead to a louder and harsher sound.
And if you only remove the first pair of diodes you will get a Colorsound Supa Tonebender (which actually is based on the Big Muff wiring).
Those who love to experiment with these different clipping options can also add different diodes which can be activated by a switcher.