need help with final debugging on dallas style silicon fuzz [please!]

[bobster]

hi guys-
sorry to trouble you with yet another fuzz enquiry. i have a question on a problem im having with a home build dallas arbiter style silicon fuzz using two bc109c at 508hfe each.

im getting a nasty crackly and fizzy sound when effect is on at full level when i turn up guitar vol pot to max....down at about 8 and below on guitar pot it 'cleans up' great-

i have tried 2 x 100pf caps over both transistors collector and base , also a o.oo2 cap over input jack to ground and a 50k pre gain pot but problem is still there. i only ever turn fuzz pot high enough to before oscillation starts and also have a trim pot for bias and get 4.5 volts on collector of tranny 2.   i have also tried two lower gain transistors but they dont make much difference either
                             so.........im stumped !!

i dont want to give up on this little dude as its soundin real good and powerful otherwise so any suggestions as to where i can look next in the circuit to smooth this out would be most appreciated     [ btw , i have one or two nice germanium diodes lying around , could i use these in any way to help? ]
cheers - bob

[tcobretti]

Have you tried a different guitar?

[bobster]

yup , all guitars act the same....

i have 2.2uf input cap , would it help to lower this ?

its nearly there but the fizziness is spoiling things for now           

anyone have any other tips? ive tried the search facility but dont come up with any more than ive done already-
cheers - bob

[bobster]

hi guys-
sorry to trouble you with yet another fuzz enquiry. i have a question on a problem im having with a home build dallas arbiter style silicon fuzz using two bc109c at 508hfe each.

im getting a nasty crackly and fizzy sound / artifact when effect is on at full level when i turn up guitar vol pot to max....down at about 8 and below on guitar pot it 'cleans up' great-

i have tried 2 x 100pf caps over both transistors collector and base , also a o.oo2 cap over input jack to ground and a 50k pre gain pot but problem is still there. i only ever turn fuzz pot high enough to before oscillation starts and also have a trim pot for bias and get 4.5 volts on collector of tranny 2.   i have also tried two lower gain transistors but they dont make much difference either
                             so.........im stumped !!

i dont want to give up on this little dude as its soundin real good and powerful otherwise so any suggestions as to where i can look next in the circuit to smooth this out would be most appreciated     [ btw , i have one or two nice germanium diodes lying around , could i use these in any way to help? ]
cheers - bob

[warioblast]

Right now I have a silicon fuzz face on my breadboard, loaded with bc108c,  just one 150pf capacitor across Q2 base & collector did the trick for me.

What layout are you using ? Eric Miller from Euthymia Electronics recommended in an old thread to make the connections between the bias resistor of Q2, the 330 ohm resistor and the ouput cap as short as possible.