Notes on Fuzz

Biasing: http://www.physics.mcgill.ca/~grant/Stuff/fuzzface.txt

http://www.theohartman.com/fuzz_faq.htm#Q:%20What%20is%20Bias%20and%20why%20isn't%20Bias%20Control%20a%20standard%20feature?:

the bias of the transistors of the fuzz circuit establish headroom (and thus its complement, breakup) in much the same way bias does on a tube amplifier. In both cases, the bias, or operating point, can be set permanently with a resistor soldered into the circuit board, or adjustably, with a trim-pot or knob. The original Fuzz Face established bias with the permanent/resistor method. It is worth noting that since every resistor has a tolerance (we use the same 5% carbon-composition resistors used in the original circuit), and no two Germanium transistors are alike, that you cannot mass produce Fuzz Faces with this bias method because each unit must have its transistors selected to bias correctly with the components on-board. HARTMAN Vintage Germanium Fuzz are built by fixing resistor values and selecting the transistor values. Again, not the only way it can be done, just the way we happen to do it.

If the Ge transistors selected are stable, in range, and pedal gets used in "normal" conditions, bias only decreases the amount of fuzz available. It does not significantly alter the character of the fuzz in quite the same way it does on the BC108 Silicon models (which is why it IS a standard feature on those). It's a "less-is-more" thing: one less component to fail, one less knob whose setting you have to worry about, one less gimmick.