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.
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Showing 1 response by dc007

Possibly a micophonic driver tube. Gently tap on the top of the driver tubes when it is playing and that should cause the offender to make a little more ringing. I doubt it is one of the EL34's. Not very familiar with the Klimo's