[Philip_T]

I just noticed this morning a strange sound coming from somewhere. After some investigation, it was a buzzing/humming sound coming from inside my Parasound 855 amp and would cycle getting louder and then quiet. The amp was not on and in standby mode. I don't use a trigger but rather manually turn it on and off from the front switch. I unplugged it before I left for work just in case. What would cause this buzzing sound? A bad power supply? I never noticed it before until it started to cycle between louder and quiter buzzing. TIA
Phil

[JackS]

Phil- Except for the intermitant increase and decrease in buzz, I wouldn't be too concerned. At present, I have a total of 5 amps and two receivers which all exhibit a little hum or buzz. If this is something that you have to consciously "attempt to hear" when no source is playing, I'd call it normal. If it's audible during a music or movie session, then you may want someone to look at it. Someone on this forum a year or two ago stated that they were successful eliminating the buzz by isolating the transformer from the case using rubber washers. This seems a little drastic if you are not being annoyed in the first place.

[Ernest Yee]

Maybe it's a groundloop of some sort. Have you added any new equipment or lighting in your house?

[Philip_T]

I doubt that I would be able to hear it while playing a source. Its only when the room is quiet that I can hear it. You know when you turn on an amp, you can hear a small buildup charge sound (for lack of a better term) then the click?, well, thats the same noise Im getting, but cycling (and no click of course). I dont think it would be a ground loop as the noise does not travel to the speakers, but, maybe a ground loop affects more than speaker buzz. I'll take a closer look at it tonight to see if there is something else I can discern. Thanks for the replies so far.
Phil

[Chu Gai]

I'd email Parasound, but from your description it does not appear to be a ground loop. Rather, I'm thinking that the power supply may need to be tightened down and/or whatever rubber spacers there are need to be replaced.

[Kirk Mango]

Phil,

I have owned my B&K equipment for 4 years and recently, after coming back from a trip and plugging my equipment back in, noticed the same thing. First it was my big Ref 7250. It would like cylce. Start out with that low normal hum any amplifier gives off if you listend closely to it, then it would get louder until it reached a peak in about 5 seconds and drop back down in volume. Never got real loud, but loud enough for me to hear just standing near the amp. Much louder then the normal hum. This would continue on a repetitive cycle every 15 or 20 seconds. I turned everything off, went downstairs to my fuse box, and popped my breaker on and off. Powered everyting back up and it was gone for 3 days. Then it started up again. This time not only with my 7250 but also my Ref 2220 which runs my mains. What is interesting here is that both amps have their own seperate circuits and seperate circuit breakers. Both amps going bad at the same time, I don't think so. On a hunch I went to Best Buy, bought two new breakers and replaced my old breakers. By the way, these are 20 amp breakers. It has been 2 weeks now and no cycling hum (knock on wood). Breakers will go after a while, just like a fuse might go, and my amps pull a lot of amperage and have been doing so at least 3 times a week for 4 years. I think my breakers where going and this was limiting the current draw to the amps. This caused my power supplies to hum and cycle as they tried to build up current draw. That is my guess anyway, I am no electrition. Let us know if this helps. Try changing the breakers.

KM

[Chu Gai]

Worth a shot and cheap to do. My son used to live in Naperville Kirk...nice place!

[Philip_T]

Kirk,
Thanks for tip. Your description sounds exactly like whats happening to my amp. Will give it a shot and try not to electricute myself in the process. :b

[Alex_P]

Pardon my rudeness, this is a lil off topic. As I read your subject title "My amp itself is humming internally", I can't stop but laugh... Humming itself internally