jrose92081

When you put the new el34's in did you attempt a bias? You may want to have that done in case the amp rating was to high or low. All tubes are slightly different.

The big power tubes or the little preamp tubes? Both matched tubes should be consistent with each other. One brighter or dimmer usually means you have a tube going bad. That would explain your bad noise. I would take it to a authorized service tech for line 6 and have him change the tubes. If they are the little tubes (preamp) you can change them yourself but I would watch a how to video on YouTube first for safety reasons.

I have the same issue it seems. I was playing straight into the amp (without HD500) and as I was turning up the volume I got a loss in power and a bad hum. I reset the amp and turned it back on, same issue but noticed a pop when i took it out of standby. Now the amp has very little power and is very dirty. Even voicing 1 is really dirty even with the drive at 1 in full power mode. Class A seems to have a louder hum. I had the tubes changed and the amp biased and same results. I even re-installed the firmware. I love this amp and the fact that it is a paper weight breaks my heart. I have it narrowed down to the processing board or the transformer. Any help would be much appreciated.