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Amplifier hum: Does it need repair?

I have a Bel Canto Evo2 amp. Lately, I've been noticing a low level hum from my system which is intermittent in nature. Today, it seemed worse, and it didn't go away in a few minutes like before. I turned off the turntable and determined that the hum wasn't eliminated when I moved the preamp source selector to CD. It also wasn't affected by the volume control. I turned off my Supratek tube pre-amp and determined that the hum persisted. Then I unplugged the two Vandersten subs and still heard the hum. Finally, I took the power cord out of the power strip and plugged it diectly into the wall. The hum was still there. The only thing I haven't detached are the speaker cables. It almost sounds like the hum is coming from the amp and not is not coming out of the speakers, but I'm not sure about that. I really don't want to have to ship it back to the factory for a repair. What do you think?
mlkiz
wepratt
29 posts
 
If you determine that the hum is definitely coming from the amp or pre-amp, it might very well be a DC problem. I had this happen with a receiver and it nearly drove me nuts. Tried all sorts of tests and solutions and finally bit the bullet and bought a PS audio Humbuster which solved the problem instantly.
thorman
1,262 posts
 
Also is it possibly cable t.v connection on the same line? Just a thought!
kr4's avatar
kr4
3,424 posts
 
Before I put in a dedicated line and really solved my ground loop problems (which I had been masking with a so-called ground loop interrupter), I had intermittant hum/noise directly from the eVo6 chassis when certain halogen or fluorescent lamps were used on the same power line. It usually went away with lamp recycling.

In my other house, which had better AC all along, the eVos are just fine.

In your case, it could be DC or RF-induced noise on the AC lines.

Kal
crest
22 posts
 
I had a similar problem with a McIntosh power amp last winter. I discovered the source causing the amp hum was from a space heater I was using, and it wasn't even on the same line as the amp. See if an appliance could be the culprit.
druhot
1 posts
 
I had a problem with my CA 201 and thought it was a ground loop problem. Tried for months to figure it out. Finally sent my amp to classe and it was the control panel that needed to be replaced.
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