2
Diyguitarpedals.com.au
PCB Spacing
The Big Knob PCB is spaced for 1590B sized enclosures or larger
Pot Spacing
The Big Knob’s pcb mounted potentiometers are spaced for Alpha 16mm potentiometers.
Modifications
Following is a couple of worthwhile modifications that I discovered expermenting with the Big Knob
Transistors
This ones obvious. Q1 and Q2 form the gain stages of this silicon fuzz. Increasing and decreasing the gains of these
transistors will effect the tonal character of the fuzz. In my experimentation a lot of NPN’s sounded good, I personally
perferred the S9013’s though (available on my store) as they are relatively low gain. To intention mismatch gains (like a
lot of fuzzes have), a 2n3904 in Q1 and a higher gain transistor in Q2 may increase sustain of the effect. The original
circuit used BC107 and BC108 for Q1 and Q2 respectively, these can still be sourced. Q3 is the recovery stage of the big
muff and wont have much effect on tone shaping.
Germanium Transistor Mod
As this circuit is very similar in topology to the classic circuit of the fuzz face germanium transistors can be used in place
of silicons. Note that you will need NPN germanium transistors (PNP’s will not work). I have tried low gain NPN’s (60
and 80 hfe) and they sound very good. See the sound demo of the Big Knob for an example.