Soulbender Pastyface question

[smallpoxchampion]

So the pasty face is the first germanium build I've undertaken and I just wanted to make sure I've got everything correct before I install the transistors and test the circuit. I ordered the PNP "continental" package from smallbear I believe. They sent me 3 Ge transistors, 2 Mullard OC77 and an OC71. Each transistor was labeled with leakage current and what I assume is an hfe measurement. It was sent with a colour sound schematic which differs a bit from the soulbender version I've been working on. The OC77's are labeled as Q2 and Q3 and the OC71 as Q1. How should I install these according to the Soulbender version? Is it ok to install them as labeled or do I need to switch them around to fit the soulbender version?

[mgwhit]

As long as you ordered one of Small Bear's "3-Knob Tone Bender" PNP sets, you should be fine with any of the Pastyface varieties.

[Bret608]

Matt is correct; Smallbear's Q1, 2 and 3 will correspond with those same part numbers on the Soulbender layout.

I'm curious, what hfe and leakage did they list for each transistor? I built a slightly modded Sola Sound version on the Pastyface board a couple of weeks ago. Long story short, I left off the trimmer and jumpered the pads per the BOM, and ended up finding out that this circuit needs a bit more attention paid to hfe and leakage than I thought. Don't get me wrong, it's a pretty forgiving circuit; but the Soulbender does go for a lower bias voltage on the collector of Q3 than historical Tonebender MkIII versions did. I think this can give a smoother, thicker sound, maybe a bit less aggressive but I'm not sure. Also, the Soulbender trimmer/10k in R7 setup works well if your transistor for Q3 isn't leaky. The old Sola Sound, Park, etc. versions didn't have that setup at all (on the Pastyface board that would be R7 empty, no trimmer, and pad 1 and 2 in the trimmer space jumpered). But they had Q3 filled with leakier transistors that could bias up at 2 to 2.5v easily. I used non-leaky ones for sure and got 3.8v with R7 empty. With 1m in there and no trimmer I have 1.8 or so volts at Q3's collector and actually the best sound among all the tweaks I made.

[smallpoxchampion]

Matt is correct; Smallbear's Q1, 2 and 3 will correspond with those same part numbers on the Soulbender layout.

I'm curious, what hfe and leakage did they list for each transistor? I built a slightly modded Sola Sound version on the Pastyface board a couple of weeks ago. Long story short, I left off the trimmer and jumpered the pads per the BOM, and ended up finding out that this circuit needs a bit more attention paid to hfe and leakage than I thought. Don't get me wrong, it's a pretty forgiving circuit; but the Soulbender does go for a lower bias voltage on the collector of Q3 than historical Tonebender MkIII versions did. I think this can give a smoother, thicker sound, maybe a bit less aggressive but I'm not sure. Also, the Soulbender trimmer/10k in R7 setup works well if your transistor for Q3 isn't leaky. The old Sola Sound, Park, etc. versions didn't have that setup at all (on the Pastyface board that would be R7 empty, no trimmer, and pad 1 and 2 in the trimmer space jumpered). But they had Q3 filled with leakier transistors that could bias up at 2 to 2.5v easily. I used non-leaky ones for sure and got 3.8v with R7 empty. With 1m in there and no trimmer I have 1.8 or so volts at Q3's collector and actually the best sound among all the tweaks I made.

Q1 hfe- 75 L- 291
Q2 hfe 89 L- 184
Q3 hfe- 153 L- 266

[Bret608]

Thanks for sharing! I bet it will sound great. Those numbers would also work for a two-knob Tone Bender. Does the schematic Smallbear sent look a lot different than the one provided with the Pastyface?

[smallpoxchampion]

Not particularly, mainly just different value components.