[AtomBoy]

My first amp at the top of this thread had a buzz that was like a tablespoon of sand in your shoe. Take two with the isolated star ground had a buzz like a teaspoon of sand. Getting rid of the loop of wire for the bias test points has left a buzz that's like a pinch of sand. I hardly know its there unless I really pay attention between songs and I'm not distracted by the girls playing vollyball.

The buzz doesn't change with the vol pot, moving the amp arround, touching the plate, or moving the wiring in the guts. I'm ready to believe that the noise is all coming from the 6 clam unregulated wall wart.

Things I'll try next-

1) Stick a bigger cap in the power suply part of the circuit.

2) Ground the little board with the buffers to the ground terminals instead of the shared ground for the tube plate.

3) Put a plug on my Condor PS and see if it really is the PS.

4) Wrap the whole thing in foil.

One of the tubes is very microphonic and the other is not - how weird is that? I saw a post somewhere talking about microphonics being realted to ultrasonics in the circuit. I'm reading some of the old books posted on Pete Millett's site-

http://www.pmillett.com/tecnical_books_online.htm

This page is a goldmine! Basic Theory and Applications of Electron Tubes is very understandable for the rank amature like me, so maybe I'll have a clue soon. The more I learn, the more magical it all seems!

 

[rickcr42]

funny how the little things can make such an impact on the sound.


my take is that electonics is the science but audio is art and when you combine the two and get it right it is as you said magic

Pete's site is a tremendous resource and i downloaded every manual there and printed them out as they were posted.everything we do in audio has already been done and that mostly more right than modern circuits.To read the old manuals is to get a real grasp of what is possible using old techniques with modern materials.The ultimate.

glad the amp is coming around.I might suggest when you are ready for an entirely new power supply you go to the Duncan Amp site and download the PSUD,the power supply designer software and model a power supply using a CLC or CRC filter as the final filter to the Millett Hybrid then if you have any noise left it will all be tube dependant and time to cheery pick tubes and go with matched sets tested for noise levels.