Basically the Marshall Supa Fuzz is a Sola Sound Tone Bender MKII, but with some different capacitor values and it uses Mullard OC75s for all three transistors.  It sounds killer, and cleans up really nicely using the volume control on the guitar.  When you hear the fuzz, it's hard to imagine the clean sound, the fuzz is supa...  This is really something that MKII Tone Benders are known for.

Like all Tone Benders using germanium transistors, there can be a bit of a process involved in selecting and/or biasing transistors.  There's quite a lot of opinions out there on various forums - if you have the chance, get it on a breadboard first and try a few different combinations.  Doesn't take long, and it removes all the guess work prior to soldering.  Apart from that, once you get it on a breadboard and hear it for yourself and notice how it responds to your guitar, the opinions of people on forums disappear.  You like what you hear, not what you read.

If you're suffering low volume, but like the sound, the standard Fuzz Face volume mods will work.

MARSHALL SUPA FUZZ - POINT TO POINT LAYOUT

 

MARSHALL SUPA FUZZ - SCHEMATIC

MARSHALL SUPA FUZZ - VISUAL ANALYSER

Signal: 440hz sine wave, approx 130mv TRMS

GAIN 100

 

STRAIGHT OFF Q3 COLLECTOR