Have I damaged my amp?

I disagree with Tarsando. Tube amps are never to be driven with no load on the outputs.

Tube amps are never to be driven with no load on the outputs.

This has been my understanding too. It's always a good policy to shut it down, give it about 30 seconds to bleed off any residual charge, and then do your changes in wiring. Never run a signal through a tube amp without a connection to a load. Opposite of what Tarsando said, I've do not associate a similar limitation with SS amps (running a signal through an SS amp with no load connected will not likely result in any risk of damage - but I would NOT do any hot-swapping regardless). Since this has been my understanding, I hope anyone with contrary information might chime in. So, with SS I'd still power down before doing any wiring changes. I would not hot-swap with a live component, SS or tube. I've seen others do it with no consequence, but I think it's a bad habit to get into.

When you say you "unplugged the Rt channel only", do you mean you unplugged the interconnect from the amp/preamp, or do you mean you pulled the speaker cable connection?

It wouldn't hurt to replace the Chinese 6SL7's with some better NOS tubes from a reliable source. That would likely improve your performance, though it may not solve the problem. Not surprising that a pencil tap yields noise though...I should think that's pretty normal for an input/driver tube. That might be a good, and inexpensive start to troubleshooting the problem.

If you swapped valves, as you indicated in your post, with no change (noise is still in the right side/amp) it would seem to eliminate a bad valve. Your description of a "rustling sound" does, however, sound like a bad tube, so I still think either testing the tubes, or swapping them with tested tubes that you know are good would be a worthwhile approach.

Marco

Thank's for the replies,

I turned the volume down and then swapped the speaker, I wasn't thinking. I'm currently using another amp because it's not enjoyable waiting for the noise to start, as I said I have tried swapping the valves one by one (with the amp off and cooled down ;) and the noise stays in the right channel which is why I'm puzzled (I wouldn't have posted if it had followed a valve). At switch off it's loud more tearing than rustling.

Iain

I don't think it's a good idea to run any amp without a load, but a tube amp with a transformer is more likely to endure it than an ss amp. That's always been my understanding of it. I know for sure that SHORTING the speaker leads blows an ss amp almost every time (unfortunately for me) but doing so with a tube amp doesn't seem to harm it. I could be wrong about the whole thing I guess....

Hmmm, if you turned the volume all the way down and pulled the speaker connection, that in and of itself would not likely damage the amp since there's no signal to the amp. Still, not a good habit to foster. Had you shorted the connections on the disconnected wire you would likely have blown a fuse (assuming they are fuse-protected). Could you have crossed the terminations and shorted the amps? That's very easy to do with a speaker wire flopping around. Regardless, short of the tubes being bad, it seems like you should take the amp to someone who has the expertise to test out individual components within the circuit. I don't think damage will always necessarily be visually evident.