Tube power amplifier low static on one channel

Filter cap.

Ah will have it checked.  If the filter cap is good next item?

jh

Try swapping the power tubes

Ok great idea. I did some research and the sound a bad filter cap makes is a hum. I don't have a hum it is a changing low level static. 

Will do the power tubes and update the post.

jh

It could be two other things - 

- Dirty or loose tube sockets. Inspect, tighten and clean the contacts in the tube sockets

- If you have digital electronics adjacent, such as a router, WiFi modem, satellite, etc, that could be causing the static out of just one channel. Make sure anything of that sort is at least 3-5ft away from tube electronics.

Don't trust your memory, make notes

All cables and connectors are good? IOW, make sure you are not hearing the random result of a poor connection elsewhere.

Switch L/R inputs 1st, that way, if the noise moves, it is coming from a different piece of equipment prior to the amp

Switch speaker wires, noise moves, it is that connected side, noise doesn't move it's perhaps in the speaker's crossover

How old is the unit?

If the noise does not move with the tubes (swap one at a time, keep track of original locations) it's time to check the entire unit, not just find one thing.

Another reason a simple tube tester is good to have. 

Power tubes get biased, how does your unit handle that?

Found it!

It was one power tube which I isolated by switching channels and following the static. The power tubes are new stock so I didn't think it could be them but it was.  Thanks for the help.

jh

 Glad you found the issue. FWIW I had a new pair of Gold Lion KT -77’s with about 15-20 hours on them. I started getting noise and before I could act boom ! The brand new tube let go and blew out the capacitors in the respective channel. You just never know.