2. amps-preamps
  3. 1196443036

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.
jpstereo

Showing 1 response by jtimothya

jtimothya
612 posts
 
I agree with Newbee's response - tubes can turn microphonic after they get some time on them - its not unusual for microphony to show up after a few weeks of initial use. Might be worthwhile to have a few extras on hand anyway, so getting some replacements to try will let you swap them around to locate which tube or tubes are the culprits.

Fwiw, tube dampers can ameliorate microphonics and give quieter output. Herbie's Audio Lab dampers are the best I've tried.

Tim
More to discover