Tube Question--Slight Ringing coming from one side


I am running a pair of Klimo Monoblock amps, EL34 based. I baised them about 2 months ago, pretty much everything has remained the same except I had to move them closer together and closer to my turntable. Within the past 2 weeks, I have noticed out of the left monoblock a slight ringing (not really a ringing, but kind of like the sound of a refrigerator at idle) not at idle, but when the volume is turned up to a conversational listening level. it increases as the volume is raised

I have never experienced this before in this amp or any tube amp I've owned in 20 years. I thought of using a tube damper on the el34, but this is not addressing what may be a problem. Could it be the tubes are ageing? I was able to bias them exactly at factory specs 2 months ago.
justlisten

Showing 2 responses by atmasphere

The complaint is a description of a microphonic preamplier tube, occuring before the volume control in the signal path. The amp has nothing to do with it.
EL34s can make a 'jingly' sound that emenates directly from the tubes- in fact from the filaments.

If the output of the amplifier were shorted or open, the tubes would also make a jingly sound that would be associated with the power demands of the music they are trying to amplifiy. This is why they would get louder when you turn up the volume.

Its not a good idea to run the amplfier this way! Make sure it has a proper load.