Sunflower Fuzz - Low, Gated Output, bias trim not working

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PangeaDestructor

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Such a simple build, I even got my Ge transistors as a selected pair (from Barry at guitarpcb). They are PNP, the pinout is correct, charge pump is from Tayda, everything looks right to me, the vrefs are correct. However, the bias trimpot does nothing (changes q2's range by about -/+ 0.2v), the output is low and gated - no sustain at all - with an audio probe I get a pretty substantial volume drop at the tail end of each component (e.g., signal is full volume entering c1 and barely audible leaving the capacitor, same with r4). Pics attached, including the charge pump voltage, any help appreciated!
 

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Just want to chime in that I have built a crap ton of these on this exact pcb w/ zero issues with the pcbs... 99.9% it is user error or bad components. If you guys are shooting from the hip with germaniums bought from a vendor and don't have the tools to measure the HFE and leakage correctly you are likely getting lucky if a build works... You really need to confirm with either a breadboard RG keen method or have a tool like the DCA 55 or DCA75 pro to measure them well... There's a lot going on with a simple circuit like this and germaniums.... one thing out of spec affects the entire circuit.
 
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Just to add on to what swelchy said, this is one of those circuits that is best to breadboard first to make sure your transistors are going to work in it or socket both the transistors so that you can plug and play different ones until it works.
 
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FWIW I have this circuit on my breadboard, and with Russan MP21E. What I have found is that R1 (in the Sunflower Fuzz build docs, R4 in a standard Fuzz Face circuit) has a much bigger impact upon trimming the Q2 C bias than the bias trim pots above R3. I put a 100K trimpot at R1 and trimmed down to get Q2 C to -4.5V, and then adjusted the other bias circuits to get my Q1C / Q2B to 0.7 V.

With the lower gain MP21 transistor, I found R1 at around 68K makes it possible to move Q2C around the -4.5V target much better. I bet if you make this change, you will find your MP26A's sound much better.

I recommend looking at Electro Smash's Fuzz Face analysis for a really clear diagram showing what "normal" voltages should be at various points.

Lastly, the knowledge that R1 should be adjusted to address lower gain transistors is not my idea. I picked this up from Chuck D. Bones analysis of biasing transistors in this circuit
 
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