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Fuzz Face trimpots and mods

9/30/2002 12:00 PM
Matt Fuzz Face trimpots and mods
What do the two trimpots inside a Fuzz Face reissue do? One is right next to the switch and the other is on the opposite edge of the board. Is the most common mod for these to swap out the transistors to a pair that have the "correct" gain? I don't know much about fuzzes. It's super fat but there is some high-end wierdness that's going on. Maybe that's normal? Even though the tone is very fat, it actually sounds better when using the neck pickup. That sort of surprised me. Any help appreciated. Thanks.  
PS - Nothing is in front of the fuzz; just guitar with vintage style humbuckers into the FF then into the amp.  
9/30/2002 4:20 PM
Joe Gagan

I tried to mod one of these newer style FF reissues. This type you speak of came out in around 99 or 2000. They did some weird stuff to try to stabilize the circuit, and in my opinion, it is hard to make these sound good. I got *slightly* better tone by putting in silicon/ge combo [ q1 and q2 respectively], but there didn't seem to be an easy way to hack in a trimpot to dial the Q2 bias.  
I am sure there is a way, I just didn't feel like spending any more time on it when I could build a whole fF board in less time than messing with it.  
I would suggest putting a new board in there.  
Wire up my EZface circuit and stick it in there.  
easy build diagram:
9/30/2002 5:58 PM
Thanks Joe. I was hoping that the two trimpots in there now WERE to bias the two transistors but I guess not. I was able to make it sputter/cough/cut-out with certain settings (but I don't want that, I want it as smooth as possible). There does appear to be more in there than the basic FF circuit but I can't see the component side of the board. Glad I got it cheap! Thanks again.  
PS - just out of curiosity, what are the two trimpots for?  
9/30/2002 7:01 PM
Joe Gagan

I can't remember what they were for exactly, but I remember they weren't useful for setting the Q2 bias. I think one might be for Q1's bias, which is weird.
10/12/2002 9:01 PM
From my web site:  
The current Dunlop Fuzz Face reissue has the switch mounted to the board, and several changes to the circuit. See below for a picture of the previous version from 1993 - mid 2000. There are two trim pots on the new model, but not in the same part of the circuit where Fulltone and others put them. There is one in place of the 100K resistor that goes between transistor 1 input and transistor 2 (actually a 56K in series with a 100K trim pot, so if you set it half way you get the normal 100K). The other is in place of the 33K resistor going from transistor 1 to zero volts. Again they use a 100K trim pot, in series with a 10K resistor, so you can dial in 33K if desired. There is an added cap to ground on the input. There is an added cap and resistor on the 1st transistor which normally just goes to +9V. There is also an RT-1 (thermistor?) device to ground on the direct connection between the 2 transistors on the signal path. The Fuzz control capacitor on the wiper of the pot is now referenced to 0V instead of 9v. So  
Regards, mike ~^v^~ aNaLoG.MaN ~^v^~ vintage guitar effects  
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