It's a stock Crack with Speedball build except that I've put in a Sylvania 7236 Tube.
There was subtle hiss prior to replacing the 6080 with the 7236, but now it is a greater than before. Volume doesn't change the hiss except when the amp is warming up there is crackling at very high volumes.
Interestingly when I replaced the 6080 with the 7236 there was zero hiss, but it came back after a few hours.
I can't find any bad solder joints as I've resoldered every single one.
I know the tube takes 100s of hours to form a cathode. Could that be the reason for the hiss or is the circuitry in the amp a concern.
Since it is only on the right channel it worries me. It's not outrageous, but when I put my headphones on you can tell its there.
Tapping the 7236 tube gives no feedback in the sound, however, tapping the 12AU7 does.
