pnp fuzzface bias

[lowstar]

hi everybody,
i recently built a pnp fuzz face that i could not get to bias right (4.5) until i used a 50k trim pot instead of 10k.
is this normal ?
i used a pair of ac122, q1~70, q2~110.

any fuzz-face-expert out there who can explain to me ?

cheers,
lowstar

[petemoore]

  RG can.
  Check out the DEBUGGING thread.

[mac]

It depends on transistor leakage and gain. I have 2sd352 that bias at 12 - 15K and 2n388 that bias lower, 5 - 8k like silicons.

download this (if you get strange results swap the decimal separator "." to "," or viceversa)
http://geocities.com/guitarfxs/exes/FuzzFaceBias.zip



mac

[lowstar]

hey, thanks ! 
the ac122 i use are not that good...that´s probably the reason...too much leakage.

cheers,
lowstar

[Stephen]

YOU also need to sound good too..

Biasing puts it in range but a higher voltage reading sometimes sounds better.....I am no means an expert this is garage ENGINEERING

[Dai H.]

thx mac, that is very neat!