Conrad Johnson Premium 12 - Noise when turned on

I would get a new 6550 from C-J. Not sure if you have the GE or Svetlana, they now use Svetlana though. You should be able to isolate it to which monoblock first. That narrows it down to 4 output tubes, once you figure which mono it is coming from. Take the new tube, put it in place of one of the four, and fire the amp up. If it persists, put the original tube back in it's slot. Then repeat this procedure, inserting the new tube in place of the second original tube. Then , same for steps 3, and 4 if necessary. Hopefully, it's just a tube. Nice amps BTW. Keep us posted.

Had an even simpler thought. Once you have isolated which mono, use a 6550 tube out of the amp which is OK. This way,
you won't order a tube you don't need. I would order it anyway just to have spares though. It's been a while since I had my 8A's. Normally a red light indicates a bad tube.
However, in this case it just may be a noisy one. I always loved the Premier 16 combo w/ my 8A's.

Thanks Fjn04. I will find time to do the exercise. Hopefully its just a bad tube.