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will a low 60Hz harmonic hum wear out my speakers?

Hi everyone,
I have what is most likely a noob question: I have a nice sounding system consisting of a digital source (newly acquired Oppo BDP 95), a Quad 99 and Quad 909 pre-amp/amp set and Usher tower speakers. The amp generates a continuous, low hum audible in the tweeters. It is only audible with the ear next to the driver, and not an issue in listening. I like to keep everything always on, which is the recommendation I got from Quad and makes sense (it also sounds a lot better to my ears then when turned on fresh and cold). All would be good, but I wonder: in time, will that constant hum wear out or age my tweeters? It is after all the equivalent of constantly playing them but at a very, very low volume. Is this a real concern, or am I being paranoid here?
The issue of what causes the hum and how to get rid of it has been discussed and explored at length without a solution. It is probably the fact that the Quad does not have much in the way of insulation and signal cleaning (built that way) and no amount of power conditioning (I tried) or outlet-plugged signal cleaners etc etc (tried them all) gets rid of it.
Thank you in advance for any advice.
roc_doc
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roc_doc OP
55 posts
 
Ojgalli,
I tried a different amp in the same set-up and no, there was no buzz at all. I also disconnected everything upstream and the buzz was there with only the amp connected to the speakers.
So, yes, given that the connections into the amp change this BUT it is something that clearly originates in the amp, we conclude that... ??
roc_doc OP
55 posts
 
Elizabeth,
I am sure SOMETHING would be audible if you try hard enough. In my work, we often say that all you need to do to find an abnormality is to make your diagnostic test more and more sensitive, you will find something...
But as stated before, since this is more easily audible than I am completely comfortable with (1 foot away if the room is quiet) I was concerned with what it may do to the speakers.
Again, not that I don't enjoy my over-intellectual paranoia, but if this is indeed common and not a cause for damage over the long run, I'm fine with it, I'll adopt the buzz as a pet... But if it can be done away with, I would prefer it...
almarg's avatar
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almarg
9,670 posts
 
11-02-11: Stringreen
Have you tried orienting plugs 180 degrees? If you use 3 wire plugs get a cheater from Home Depot, cut/saw off the grounding plug and try turning (one at a time) the plugs of the stereo. If you come across the culprit, change the wires going into the plug behind the wall and get rid of the just bought "cheater".
No, do not do any of these things, most especially the last suggestion, which would create a serious electrocution risk if a component in which ac neutral and chassis were connected together is ever plugged into that outlet. Some vintage components were designed that way. With any component that condition could arise due to an internal insulation fault, a wiring error, or a part failure.

And reversing the hot and neutral inputs to any component, either with a cheater or within the outlet, will cause the component's power switch and main fuse or breaker to act on the ac neutral ac wire, rather than on the ac hot wire, which could cause possible internal fault conditions to result in a fire hazard, a shock hazard, and a hazard to the component.

Regards,
-- Al
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almarg
9,670 posts
 
Assessing the level of hum or buzz when the amp inputs are disconnected from the preamp will only be meaningful if it is done with shorting plugs (or something equivalent) connected to the amp inputs. Without shorting plugs the amp may simply be picking up interference out of the air and confusing the results of your experiments. The other amp may have behaved differently simply because of differences in input impedance or other parameters.

As for the original question, the amount of power going into the speakers that would result in the sound level you are describing is miniscule, and will not hurt anything either in the short term or the long term.

Regards,

-- Al
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