Weird problem biasing a Fuzz Face clone

[Hazrus]

Hi all, first post! 

I have just built a Si NPN fuzz face clone, copying Dragonfly's vero layout in the gallery (thanks dragonfly!) with a few changes:
2k fuzz pot
10k bias pot
470 ohm resistor instead of 330 ohm.
2N222 transistors

Everything works well, volume works, fuzz pot works, etc. The only problem I have is that I can't get the bias down to 4.5V on Q2 collector. I turn the resistance on the pot up full and get a minimum of 5.9V.

Anyone got any ideas why this should be? I am using a 10K pot instead of the 8k2 bias resistor.

Dragonfly's vero layout can be found here:
http://www.aronnelson.com/gallery/main.php/v/DRAGONFLY-LAYOUTS_0/album18/album144/SILICON_FF_VERO_001.gif.html

edit: voltages are:
Q1:
C: 1.36
B: 0.6
E: 0

Q2:
C: 5.9 (minimum) to battery voltage (9.5V)
B: 1.36
E: 0.76

Thanks!

[Solidhex]

Yo

  Its most likely the 2k fuzz pot throwing everything off. Either switch that to a 1k or get a 25k bias pot instead of the 10k.

--Brad

[sengo]

For some odd reason on my Fuzz Face clone I had to use a much larger than typical pot to bias Q2 correctly. I ended up using a 250K pot before it would bias correctly. I don't *think* this makes the fuzz sound different than how it is suppose to, although I'll admit mine does not sound exactly how I expected it would, but I have some very bassy pickups on my guitar, and I modified mine with a large input cap a la Hendrix.

Nick

[Hazrus]

Thanks guys! I'll put a bigger pot in there or put the 1k as the fuzz pot and see what happens.

[Hazrus]

Tried it tonight and works great. With a 1k fuzz pot I can get the bias on Q2 collector down to about 1.4V. As usual, DIY stompboxes have the answers