GGG Boutique Face Build

[erick4x4]

Ok, so I just built this and a have a few questions, if someone could help me.

There is a 10k trim, and a 50k bias pot, can anyone give me a "mathematical" way to set these? I have done it by ear but am unsure.

Second, it has a countour pot, but it mostly changes volume? At the highest setting it does "thin" out the tone, and thin out the volume. At the lowest setting it is more fullrange. Is that the way it is supposed to work? If so that's fine, it has tons of volume, so no problem there.

Lastly, maybe the "boutique" option was a bad choice, but it almost sound too clear for me, I really wanted nasty thick chainsaw fuzz, but even at max gain, it is still tight enough to be like a broken up distortion. Is that right? I have heard the dunlop/dallas reissue, and it sounded much nastier (maybe its just my bias settings). Oh and I bought the matched Germ US set from small bear.

Thanks!

-Erick

[erick4x4]

Ok, so I answered one of my questions. I just listened to the '69 fuzz on fulltones website, mine sounds exactly the same, so I guess the "overall" sounds are good.

Any tips on the bias and contour?

Thanks!

[burnt fingers]

I don't think there is a mathmatical way here.  It's just what sounds best to you.  The "bias"  control is just wired as a variable resistor on the input.  It just reduces the amount of signal hitting the first tranny a little.  The "countour" is replacing the normal 470ohm resistor between the battery and the 8k2 to q2 in the original fuzz face.
One common mod on FF's was to change that 470ohm to a higher value. The higher value results in more output.  I'm sure someone can explain more technicly what it does.  Anyhow, the contour just puts a variable resistor there so you can dial it down to somewhere in the range of the original FF up to a higher value. 

Scott

[erick4x4]

Thanks.

So on the input gain ("bias"), what is the original value, was it bypassed (all the way up), or something part way?

So what does the internal trim do?

[billings]

The "original" value of the Bias pot is zero.  In the plain fuzz face the input goes straight through the input capacitor into Q1.

The internal trim is there to set bias on the second transistor.  I guess that's sort of confusing given the external Bias control, because they're completely different things, but...  there you go.  The higher that trimmer's value, the more gain Q2 has.  As for a mathematical way to set bias, i have seen most people here recommend that you tweak that trimmer until the voltage at Q2's collector reads about -4.5V or so, which gives Q2 lots of room to swing without running out of supply voltage.

I didn't do that, though, and was pretty happy with my results.  I did the roger mayer mods on mine as well as all the boutique/fuller tweak knobs, and put two ~140Hfe silicon PNP transistors in the circuit.  I ended up with a fuzz face that's saturated for about the top quarter turn on the guitar's volume knob.  I wouldn't describe it as nasty chainsaw fuzz, though - it pretty much sings.  Maybe high gain silicon will do that for you?  I couldn't say.

This FY-2 clip off of Mark Hammer's site is what comes to mind for me when I think of chainsaw fuzz, though.  Been on my build list for a while....