Burns Buzzaround noise/hiss question

Started by mordechai, May 04, 2017, 02:11:20 PM

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mordechai

I recently built two Buzzarounds.  For Q1 and Q2, I used very low leakage 2N404's (at about 70/80 HFe for one circuit, and 75/90 for the other).   I tried to match the HFe of Q3 to the gains of the Q1/Q2 combo -- so on the circuit with 70/80, I used a slightly hotter Q3 (at about 150HFe), and on the one with 75/90, I used  one at about 120HFe.

Now, of those two Q3's...one had a leakage of about .15uA, and the other had about .23uA.  I cannot remember which was which, and I've since given the pedals away to friends.  The fuzztone and gain from both were about the same and sounded great, but one of those circuits had virtually no noise/hiss when I wasn't playing. 

I'd obviously like to recreate that lower-noise one...but I can't for the life of me remember which combination gave me that nice, quiet operation.  All other values and components were the same.  Any ideas or suggestions about which combo might have been the magic one?

LightSoundGeometry

chances are if the trannies are good its your field dressing and layout. you have to do these pedals like tube amps.

PRR

The hiss of Ge transistors has very little to do with hFE.

If it hisses, try another transistor.

The first stage is usually the most critical, the last stage may not matter if you have good-factory parts (not from a reject-barrel).

Very late-production parts will tend to be lower-hiss than the early production (US 1956, Japan 1960) parts which DID have to be sorted for low/high hiss.
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mordechai

That first stage used two 2N404's from an ultra-consistent batch that has never disappointed.  The gains were good and leakage was very, very low on both.  Maybe on the quiet circuit, I just randomly lucked out with one (or both) of those first two transistors.