Twin Face whine

B

Boukman

New member
Hello and happy new year!!
I have built the Twin Face (first edition) and it works ,but with some problems.
First on the NPN side with the gain maxed i get a high pitched whine but not on the PNP side. I use the correct 1044 chip.
Second i cannot get to -4,5v on the PNP side. Do i need a bigger trimmer?
Thanks!!
 
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swelchy said:
Clear pictures of your build would be first advice... Another question is did you just plop transistors in without knowing what the HFE and leakage is for the germanium.
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The thing is that even with no germanium transistors in it makes that noise on the npn side and i tried different npn too and replaced the 1044 with another.
 
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Thanks guys!!
 

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Your build looks pretty good.. soldering looks really good too. Can you double check and make sure all your electrolytic caps are the correct polarity vs what was marked on the pcb? It's hard to tell on a few of them for me.. mainly the right side I cannot make out all the way... Whine is usually something that comes up all the time with 1044's.... I wouldn't be surprised if it was a charge pump issue... swapping one from same batch might be an issue too.. do you have any 1054 charge pump on hand to try?
 
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You are biasing with the selector switched for the transistors in use, right? The non selected transistors will show +/- 9V and not be affected by the trimmer.

As to the noise, I also notice some noise on mine, but only when volume and gain are at max.
 
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I don't think anything is faulty.

If this is what I have heard on my board, I think it's a known issue with the Fuzz Face circuit. I found some discussion by one of the high-quality references (i.e. ElectroSmash or RGKeen) but don't remember who discussed this. It specifically has to do with the Fuzz pot going all the way to zero at max, causing (maybe - I don't recall precisely the circuit issue) too little feedback and runaway amplification. I think maybe Silicon is more prone to the issue.

You can fix this by putting a small resistor in-line with C3 or C5 (depending upon the side). I built a twin-face last November using higher gain for NPN (and other mods around the capacitors to modify the filters). While I deliberately want the circuit to go a little bit out of control right at the limit, I still put a 22Ω resistor inline with C5 to tame extreme squeal.

IMG_9155.jpeg
 
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