Most likely the EF86's are microphonic, not necessarily dying. Its not unusual for tubes that sound OK at first get noisy shortly thereafter, depending on their initial qualities and how hard they are driven in the curcuit. You may need to focus on getting some 'low noise' tubes. Research the needs in your pre-amp for low noise tubes and if it has a reputation for needing low noise EF86's buy accordingly. I agree its not likely that the power tubes are going bad, and I doubt that its the rectifiers either.
Tube hiss - any idea what's causing it?
I own an Eastern Electric M520 integrated amp that I am very fond of. However, recently I have noticed that there is a great deal of rather disturbing hiss eminating from my Omega XRS speakers once I power the unit up. The hiss does not increase when the volume is turned up. It's always there and very noticable during quiet passages. It's definitely a hiss and not a hum.
I checked the tubes and noticed that when I touch or slightly jiggle the front EF86 tubes, the hiss gets louder/softer when they are moved. Could it be that these tubes are going already? I do not have many hours on them. Maybe 100 at best. Should I consider replacing them or perhaps checking the other tubes too - perhaps the 5 AR4 rectifier tubes? I doubt it's the power tubes.
Do you have any thoughts/recommendations for me at this point. I am not sure how to proceed. As always, thanks for your time.
I checked the tubes and noticed that when I touch or slightly jiggle the front EF86 tubes, the hiss gets louder/softer when they are moved. Could it be that these tubes are going already? I do not have many hours on them. Maybe 100 at best. Should I consider replacing them or perhaps checking the other tubes too - perhaps the 5 AR4 rectifier tubes? I doubt it's the power tubes.
Do you have any thoughts/recommendations for me at this point. I am not sure how to proceed. As always, thanks for your time.