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buzzing from speakers

Recently picked up some used gear to assemble a decent, little condo system.

Recently noticed buzzing coming from the speakers when no music is being played. Thought it was speaker cable picking up hum from all the other cables strewn behind the wall unit, but after testing, that is not the case.

I'm concerned that the static electricity in my apartment may have damaged my amp somehow. I notice that almost every time i touch my equipment, i get a mild shock (because of the dry air in my condo coupled w/ carpet).

Could this have somehow damaged my amp /created this audible hum? I never noticed the hum in the past when i first picked up the amp, so i'm not sure if the problem has been there then entire time or if it's new.

Any thoughts?
loose
kijanki's avatar
kijanki
4,432 posts
 
You don't need to open case to create static damage. Even with properly grounded equipment it might happen if voltage is high and it is repeated many times. You'll find testimony of that here on Audiogon forum. I am able to destroy prototypes of industrial electronics zapping them few hundred times with 10-20kV zapper to heavy metal case that is grounded directly to copper ground rod (not the flimsy inductive 3th prong). It is not issue of "IF" but rather "WHEN". Situation of repeated static discharge is unacceptable.

It gets much worse if you touch something else than case - like metal knob sitting on the metal shaft of the volume pot and not touching case (small gap). Or even better zap speaker wire (and I assume that grounding is non-inductive and perfect).

If you read more about static damage - one of the first thing advised is humidity control. You'll find many posts of people who damaged their computers by strong discharge to a case.

Stay amused!
vinyladdict
164 posts
 
"Stay amused!" ... oh, I am ...
loose OP
239 posts
 
well, since my initial post, I've disconnected the cable box, which made no difference. Following that, i disconnected speaker cables (and actually introduced others that I had lying around), attempted to isolate the speaker cable as best i could, yet the buzzing remains.

It's non-intrustive when music is playing and not noticeable, even without music playing, from the seating area.

I was told by a service technician whom i trust that static is not likely to cause any damage to an amp, however I'm still somewhat concerned only because I hadn't noticed it beforehand (although i never actually LISTENED for it when I first set up all the used gear).

Beyond that, another audio store owner suggested that many somewhat 'esoteric' amps have some background noise to them and that the amp may be working within its parameters (it's a Sugden A48b running Rega Ara speakers. Source is a Rotel rcd971).

Another point I failed to mention is that the amp has been modded by one Dan Santoni (I don't know if this means anything to anyone) who is apparently quite reputable.

For the moment, I'm simply going to live with it, as everything will be upgraded eventually anyway, starting with the CD player, i think...

Which brings me to a new thread ...see the Digital section .... 'Weak Link'
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