setting bias, transistor selection

[Chevy]

New to the world of fuzz... just built a Sandspur. Would like to tweak it to its best.

1) I've read that some users set the bias to a specific voltage... where do you measure the voltage and what to set it at?

2) Not knowing anything about this, I just ordered the only BC108 option at Tayda... the 108B. Now I find there are 3 gain ranges available at other vendors. Which are best for which position?

4) Can I swap in BC183's in for the 108's the exact same circuit? I don't have a Transistor gain tester... use the A, B, or C version?

5) Any suggestions on how to get most out of this pedal?

 

[jwin615]

Chuck has some good write ups in the boneyard
Here's part 1
I think part 3 covers the FF, which is what a sandspur is in heart.
I'd also recommend checking out the RG Keen write up here

 

[jwin615]

As for what transistors to use, your 108Bs will work
Different transistors do sound different, IME. Some more than others and it's also circuit/position dependant.
Also. Note that BC108 are usually EBC pinout. So IF the sandspur is layed out for EBC, you may have to reverse other transistors. I haven't built a sandspur yet but many here have. But what's "best" in a Si FF is a little subjective.

 

[giovanni]

Transistors are cheap. When in doubt, you can socket them and try a few different options.