Silicon Tone Bender MKI

[mac]

Transistors hfe and internal capacitance make a lot of difference.
I have some 2N2369 that are very fuzzy, but others from Motorola sound different. 
BD237/175/139 and TIP31/41 have high internal capacitance.
MPSA42 and 2SC1213 are my workhorses for old 60s fuzzes experiments --> hfe: 100-150, cheap, available.

I won't use any Si above hfe:150 like 2N3904 (*) because of bias and too much gain for my taste. But if super gain is what you like try BC550C or 2N5088 (adjust R5 and R8+R9)

(*) maybe a high gain at Q1 ??

mac

[Steben]

I won't use any Si above hfe:150 like 2N3904 (*) because of bias and too much gain for my taste. But if super gain is what you like try BC550C or 2N5088 (adjust R5 and R8+R9)

As I said, that would make for wooly fuzzy IMHO.
Lowering the hFE (esp on Q3) works let's say a bit like rolling back the volume on a Fuzz Face  .

[duck_arse]

I'm not in this thread yet. well, now I am. I've breadered mac's version, using med power drivers AY-6115 's w/ hFE's 68/50/62, and I get more bursting nasty tizz decay oscillation than I care for. I've been trying to bypass the collector resistors [100nF across the 2k2 works, but affects the top end], as well as the 100pF B-C caps. I'll have another go tomoz w/ the added 4k7's and see if they help.

also not much impressed by the attack/fuzz pot range - might set that at maxx and use interstage level control instead.

[Steben]

I'm not in this thread yet. well, now I am. I've breadered mac's version, using med power drivers AY-6115 's w/ hFE's 68/50/62, and I get more bursting nasty tizz decay oscillation than I care for. I've been trying to bypass the collector resistors [100nF across the 2k2 works, but affects the top end], as well as the 100pF B-C caps. I'll have another go tomoz w/ the added 4k7's and see if they help.

also not much impressed by the attack/fuzz pot range - might set that at maxx and use interstage level control instead.

Did you ever make germ mkI?

[duck_arse]

yes, indeedy, some many years ago, with japanese transistors. I remember nothing at all about the tone.

as for my current bb, the in and out stopper resistors on Q2 [2k2 at base, 1k at collector] along w/ the 100pF pair and 6n8 across the 2k2 collector resistor has tamed mostly all of the fringe-ing oscillation junk. Q3 adjusted to the quiet zone helps. overall, I'm not sure this is the circuit I'm looking for.

[duck_arse]

well, transistors, who'd a thunk it? it seems my selected transistors are far too hissy for the first stage config, tho they are fine in other circuits. odd results with low noise transistors being very much more hissy than low hFE parts.

I tried a pnp TT800 power/driver at Q1, it was as silent as I could get. will build a Heath 28 instead.

[bmsiddall]

Do you like it now?

[duck_arse]

the silicon TB mkI is an ok sounding thing, if you sort your transistors for hissy fit. but - I couldn't get it to produce any variation in tone with my tested transistors and the fuzz pot setup as standard, or as a collector-base bias vario. so not worth my building as is, with the very limited palette of parts I have in mind for a particular build style.