First thing, very loud hum, too loud to be normal, especially when all the volumes are down and no guitar is plugged in. I wanted to see what the voltages were doing and I'm getting 310 at the plates of 6K6's.
Moved onto seeing where the bias was at, at 310vdc I was shooting for about 19mA. This is where it got weird. When looking at the back of the amp the bias pot on the left functioned normal, I could get a sweep of about 1mA to 17mA neither of which had any affect on the hum. I moved to the bias pot on the right, as I turned it down closer to 0mA the hum disappeared, as I raised it up approaching 19mA it begin to whistle loudly and into feedback. The other thing is that the bias pots were interactive, if I adjusted one to 15mA and then did the next one the same, when I came back to the first one, it had moved. I don't remember that being the case with other dual bias control amps I've had.
The only thing I've tried is switching the 6k6's around but it was the same thing.
Where's a good place to start? And quick question to make sure, pins 1 and 8 should be tied together like any other non cathode biased octal tube, correct?
