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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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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
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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
roc_doc OP
55 posts
 
Thanks Al,
I was not going to attempt anything cavalier wiring-wise myself, I have neither the know-how nor the courage...
Indeed, if the answer to the original question regarding damage is no, then I am a lot less concerned. My worry was not about the electronics and the amount of power being sucked in, but actually (and likely simplistically) about mechanical wearing off of the driver membranes, given the constant movement to make that noise. Does that make any sense?
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almarg
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My worry was not about the electronics and the amount of power being sucked in, but actually (and likely simplistically) about mechanical wearing off of the driver membranes, given the constant movement to make that noise.
Yes, that was understood. The very low volume, and the correspondingly miniscule amount of power going into the speakers, are indicative that the amount of movement is vastly less than the tweeter is designed to handle, given the reasonable sensitivity of your speakers (87db/1W/1m). I don't see any cause for concern.

Regards,
-- Al
unsound
7,314 posts
 
Perhaps tightening the tranny (or everything else for that matter) to the chasis of the amp might help?
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