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Hi,
Was troubleshooting 60 Hz hum coming through both speakers, though not audible at listening position, and music sounding pretty good. Have a vacuum tube linestage (Vacuum State FVP5, BEL power amps, Genesis Tech IM-8300's. All components were plugged into an Exactpower EP15A. After swapping out preamp tubes, re-routing interconnects -- no improvement. Finally disconnected the power amps from the Exactpower and plugged directly into wall. Hum now GONE, and the transformers of the preamp and power amps are now MUCH quieter.
I've been using the Exactpower for quite some time, and the increase in hum level is recent. Any ideas/suggestions? (My turntable is also plugged into the Exactpower, which should result in better speed stability, but...)
Thanks,
Harvey
Follow Ups:
Ground loops caused hum with my regenerator. I only had pre amp level devices plugged into it. (P-300) I lifted its grounds first which solved the hum issue then ended up lifting the two power amp grounds not plugged into it which resulted in more sound improvement although the hum was gone after lifting the regenerator ground.
People smarter than me have said safety grounds can act like a noise antenna and I agree. No safety lectures please.
ET
Hi ET,
Unfortunately, my reported success was premature.
Hum still present.
Tried replacing preamp tubes, but that did not get rid of the hum.
Finally replaced the tube preamp with a Spectral DMC-10 that I have -- hum gone. Any ideas/suggestions why the tube preamp would be associated with hum from both channels? -- it was quiet until a few days ago.
Thanks,
Harvey
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