fuzz transistor biasing instructions

[kefestvog]

i'm working on my first fuzz project and i need instructions on how to properly select the proper resistor values to bias the transistors.  I know that this is probably somewhere in the archive but i'm not finding it.  could someone either explain it to me or point me to the post that has the instructions.  these will have to be pretty thorough instructions as i'm very very new to this.  i'm looking for as detailed instructions such as voltages for the C, B, & E of the transistors.  Also am i correct in thinking that the resistors going to the base of the transistor is the bias resistor? (i told you i was new to this).  also, if you bias the transistors can you use transistors that don't fall into the 70-100hfe range?  if so will they still sound as good as the transistors in that range?  so many questions, help!

[petemoore]

Sounds a little like you're doing a Fuzz Face...?
 If so, you'll want at least a trimpot replacing Q2 collector resistor.
 You'll also want to read "Geo' Technology of the Fuzz Face"
 Yes the 'right' transistors make all the difference in a FF...
 Of course till we know if it's a FF, whether is NPN Neg Gnd or PNP Pos Gnd or something else, I simply direct you to general Fuzz Face articles.

[kefestvog]

I am planning to build the Fuzz Face.  i'm planning to start out with a Germanium PNP (Pos Ground) so that's what I'm most interested in right now.  So that's what I'm wondering about for biasing.  But am also planning a silicon version in the future.  I have a collection of BC108s, 109, and 183s for the future project.

[Joe Davisson]

Use the Fuzz-Face calculator!
http://www.diystompboxes.com/analogalchemy/emh/emh.html

I haven't got the germaniums 100% yet. It should get close, but R1 has to be adjusted so the collector of Q2 is near 4.5v. I'm pretty sure Si/Si will always be exact, but mixing Si/Ge may not be, especially if Q1 is Ge. Used in conjunction with a breadboard, the calculator allows you to test out a bunch of transistor/gain control combinations in less time.

[kefestvog]

thanks,

that was exactly what i was looking for.