Your favorite silicon transistor?

[Locrian99]

Thanks for all the suggestions. I've got a strange problem recently. I've built a decent BC108 fuzz Hfe around 250 in a Dunlop Jimi Hendrix replica -but it's a bit bassy for me. When I try to replicate it with any of the transistors in my stash in a Sunface/Conventional fuzz face type circuit. I get an ugly tail off on the sustain. It's doing my head in. The JH replica has an 82K feedback resistor - does this make a big difference. BTW I know about bias measuring a bit, I've noticed with sunface circuit Q1 is often lower volts than in the JH - should I just abandon the usual 33 K resistor for Q1? Cheers

It could be a result of the bias. For the collector of q2 replace with a trim pot and fine tune from there. Id look there first then elsewhere

 

[Chuck D. Bones]

Try reducing the 2.2uF cap at the input and/or put a 10K trimpot in series with that cap.

Which guitar / pickups are you using? These vintage-style FFs are very sensitive to what's driving them. Both a blessing and a curse.

 

[gtfields13]

Thanks for all the suggestions. I've got a strange problem recently. I've built a decent BC108 fuzz Hfe around 250 in a Dunlop Jimi Hendrix replica -but it's a bit bassy for me. When I try to replicate it with any of the transistors in my stash in a Sunface/Conventional fuzz face type circuit. I get an ugly tail off on the sustain. It's doing my head in. The JH replica has an 82K feedback resistor - does this make a big difference. BTW I know about bias measuring a bit, I've noticed with sunface circuit Q1 is often lower volts than in the JH - should I just abandon the usual 33 K resistor for Q1? Cheers

Hmm. If you are bassy but otherwise happy, you might changing capacitors instead. When I was working out my last FF, I tried out capacitors fro 0.1µF to 2.2µF at C4 (input) and and 22nf to 3.3nF on C3 (output). On my last build (with 2N2222A's) I went all the way down to 50nF on the input capacitor (copying the Fudge Round variant there).

I have always ended up much lower than 100K for my feedback resistor on Ge PNP, where it helps set bias for the more readily available low-gain transistors, but not had to change that for NPN circuits.