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Questions regarding the original vintage FuzzFace pedals

2/22/2005 1:55 PM
Questions regarding the original vintage FuzzFace pedals
On the original vintage FuzzFace pedals, was the output capacitor a 0.1uF or a 0.01uF?  
I know that the NKT275s are really good but what about the AC128 transistors? If you get some good N.O.S. AC128s, are they as good as the NKT275 transistors? Do they sound any different than the NKT275?  
Last but not least, when they started making the FuzzFace pedals with silicon transistors, did they use the BC108C or was it the BC109C? Maybe they used both?
2/22/2005 2:59 PM
I have used NOS AC128 - sound great IF properly biased. Biasing is the key to all different transistor selections in FF circuits. Even among same part numbers - I have found VERY different results with 40 different pairs of AC-128's in the same test circuit - you need a scope and sine generator to get an accurate picture of bias/operational diffences - canot allways rely on your ears. In my experience, all suggested germanium equivalents can sound right if properly biased with trimpots in circuit - takes some fidgeting. Silicon of course sound "harsher because of different clipping and diode drop charachteristics.  
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2/22/2005 3:30 PM
Dai Hirokawa
Re: Questions regarding the original vintage FuzzFace pe
they apparently varied, so you might just go with the value that sounds good. The Arbiter resissue looked like it had two 0.015uFs in parallel(and different output volume pot value too), which would make it 0.03uF for the output coupler.
2/23/2005 1:14 PM
Re: Questions regarding the original vintage FuzzFace pedals
Thanks for your reply, I'm in New Brunswick BTW.
Ian Anderson
hey Rodrigo, how would I go about correctly biasing a transistor in the Fuzz Face circuit? - I made one years ago and have just relied on swapping in transistors till it sounded good.  
Cheers... Ian
4/7/2005 12:06 PM
skreddy Re: Questions regarding the original vintage FuzzFace pe
What I do is build it with a 100k trim pot on the collector of Q1 instead of the stock 33k resistor. Twiddle the knob until the voltage that appears on the collector of Q2 is 4.5 volts. Or you can use the calculator at to determine the fixed resistor values instead of a trim pot.
4/8/2005 9:03 PM
Boogo Re: Questions regarding the original vintage FuzzFace pedals
Rodrigo, I've got a nice scope, no sine generator yet. How do you bias using the scope? What am I looking for?
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