Original Spanish Version
Big Muff Pi Versions
Everything started for me trying to find the sounds used by Dave Gilmour for my band (The Pink Tones). His lead sound is a Big Muff, although it didn't sound like my Big Muff at all, so I decided to investigate a little bit.
After searching, comparing and tracing a lot of schematics and pedals of the different Big Muff versions, and finding messy information and uncentralized chaos, here's my attempt to put some order.
There are several versions of the Big Muff, changing values and graphical designs, but they are not as incoherent as it's usually said. The phrase "Electro Harmonix just picks whatever cheap components they have available" is true to a certain point, cause carefully tracing different circuits I saw they are more coherent (units of the same model, of course) among them than expected.
We can talk about these different versions:
Triangle Big Muff. So called for the layout of the controls. Switch to turn it ON and OFF. No LED neither DC current connector. PNP transistors. The sound is a very musical distorsion with lots of sustain. Considered the best of the Big Muffs for a lot of people. Used by Gilmour on part of the On An Island tour.
Triangle Big Muff (2nd. version), Another incarnation, uses NPN transistors, and a little less gain.
Ram's Head Big Muff. Total change of look, now it's housed in a bigger box, pots are now in a row, and letters are red. Uses PNP transistors. A little less gain than first Triangle. The tone circuit makes it sound with a pronounced mids scoop, so it makes it tricky to use in band context. It's the one used by Dave Gilmour in the The Wall tour, as can be seen in this picture (over Cornish pedalboard, the one in the left is an Electric Mistress flanger, and the one in the right is a Ram's Head Big Muff):
Third edition. With the graphics currently associated with the american Big Muff. NPN transistors. Wilder and more "out of control".
Third edition with tone bypass. Same circuit except some minor changes (3 capacitors change from 1uF to 0.1) and a switch to bypass tone control, which brings more mids to the sound.
Op-amp version. Hated by some, loved by others, changed from transistors to op-amps.
Civil War Big Muff. Used by Gilmour in the Momentary Lapse Of Reason tour, as can be seen in the picture. Less gain than Third Edition and more mids.
Green Russian Big Muff. Very similar to Civil War.
Current russian reedition of the Big Muff.
From the Tonepad schematic, which is very clean and well drawn, I draw other versions schematics, some based on schematics found on the internet, some traced by myself.
Triangle (first edition) Traced by Single Coil
PNP transistors, FS36999
In the Singlecoil, the schematic is wrong, it says 10k pots when it's 100k, and the diodes and the 50n capacitor are reversed.
Triangle (second edition) drawn by Tonepad. Traced by Aron
NPN transistors, 2N5133
Diodes and capacitor (50n) are placed reversed respect to the other triangle.
There's a capacitor missing, parallel to 390k resistor in the first transistor.
First resistor 3k3.
Missing resistor to ground in the second transistor.
Resistors from collector (or emiter in this case) to ground change in the first transistors, 820, 150 y 820 instead of 100, 100 y 100.
Ram's Head Traced by AMZ
PNP transistors, 2N5087
Project at pisotones.com
Violet Ram's Head Traced by me
Transistors, NPN FS36999
Interesting, it's almost the same circuit as the third edition except that capacitors are 0.1u instead of 1u, which makes it less bassy, and a change on the tone section (the resistor to ground is 39k instead of 100k, wich makes it more mid-scooped, but not as much as the Ram's Head.
Also, in the second transistor, the resistor to +9V is 10k instead of 15k.
Third edition drawn by Tonepad
Transistors, NPN 2N5088
Almost for sure, the missing resistor (Ra) is 100k. This is also the GGG version, though it changes capacitors from 1u to 0.1u.
Traced by MBC
Closer to the russian versions. Not as dark sounding.
Project in pisotones.com
Civil War Russian Traced by me
Green Russian drawn by Tonepad
Current russian reissue
Traced by MBC
Differences with the green russian are insignificant, just three resistor values. The one that sets the minimum sustain passes from 1k in the green russian to 10k in the black reissue. The 20k resistor in the tonestack is now 22k, and the resistor to ground in the last trannie was 2k and now is 2k7.
Project at pisotones.com
Drawn with Duncan Munro's
"ToneStack Calculator". Tone control at 12 o'clock.