Handy Hint for Tonebender MkII builders

[Toney]

 As you probably know Q1 "expects" a certain amount of leakage to bias correctly, thus the 10k/ 100k base resistor difference on the schems in line with differing transistors.
I just spend today dicking around with one of these, build with Russian GT308. Just couldn't get it sounding right at all.
It was cold as anything this morning when i started, so I put it down to that, but nope, when it was warmer, it was still far too gated, not silky at all.
Those Russian germs are TOO leak free for this application.
Then I remembered the FZ-1 I build that also "wanted" leaky Ge's, so I applied the same M.O.
I pulled out the 100k and replaced it with a 500k pot, biased right up sounding wonderful at 250k.
I checked my build notes from the FZ-1 last year - same story ~ 250k on the base was the trick to compensate for clean Ge's.

I'm sure the designers did something similar when they auditioned the original parts.

[mac]

I have some leak-free Toshibas 2SA49,52. I put a big resistor from Vcc or C to B to bias properly at 8V or so.
The 100k shunts the tiny leakage to ground making these germs to bias near Vcc. I didn't think about making it bigger! Thx.

BTW, the reverse fx is also cool, shunting excesive leakage using a resistor from B to Gnd. I did it in some FF.

mac

[Toney]

Yes, quite right.
I'm guessing that the OC81D's were quite leaky, thus the smaller 10k base resistor at Q1.
Getting the bias right on Q1 really makes these go from mild to wild.
BTW, I also took the advice of other here and biased the Fuzz Face section (Q3's collector) by ear and ended up happiest with 6.1 volts, as opposed to the often recommended 4.5