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Im generating some noise in one of my builds somewhere in the phase inverter. Its a LTPI, and Im using two halves of two different tubes( probably not the best idea, but both 12AT7s same model and what not). I pulled one tube and the noise was gone and the volume was VERY quiet(only audible when maxed out). I pulled the other tube and the noise has reappeared and the volume is where it should be considering one half of the signal is missing. I think Im right on this, but just so Im clear the tube that removed the noise and eliminated most of the volume is the 'bad' circut, right?
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Ok using this post for another question. On the subject of locating hiss, noise and hum. Pulling the phase inverter tube removed hiss and noise, and only produced a slight hum(power tubes biased very hot). Inserted the phase inverter tube and pulled the preamp tube, and a good amount of hum(different from power tube hum it seems) and a fair amount of noise and hiss came back. This means the noise and some hum is being generated between the PI and the input tube, or the PI and the power tubes?
Installing the input tube adds no additional noise, but turning the volume does add significant hiss even at low levels. The amp is very neatly laid out with quality components including a Sylvania 5751, so I dont have a clue whats cuasing that hiss. Any thoughts?
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