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
Thousands of audiophiles leave the whole system on 24/7
Many of them have an audible hum when you stick the ear right up to the speakers.
NONE of them are writing about how there speakers
"wore out"
I hope this is an answer.
It'll wear you out first....I would check for a grounding issue..it should not be audible.
Also, a 60hz hum should not be audible from your tweeters
Thank you everyone.
Elizabeth, yes, if it is so common I am a lot less worried.
Stingreen, obviously it IS wearing me out :)
Winoguy, I don't think it's 60Hz, it sounds a lot higher, but I'm wondering about a harmonic? It could be something else, of course.
One interesting thing about this, after lifting power cord grounds, trying all the power clears I could find, changing speaker cables etc etc ETC, is that it is very responsive to the kind of interconnects hooked between the pre-amp and the amp. In fact, the buzz is a lot louder if the amp is on with no interconnects hooked up to it, and quiets down some when I connect something to it. It can also be made louder by BAD interconnects. So, I should probably keep exploring (and spending, oy…) the interconnect issue.
Thanks everyone for chiming in. The immediate issue really is, if sonically I'm OK living with this, will it damage stuff downstream (ie the speakers)? If indeed it does not, there is much less urgency to this.
Shielded IC's might also help...
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I owned the Quad 99 and 909 also. You should have the quad link hooked up and the interconnects hooked up at the same time if you don't already. However, it is not uncommon to have a little sound,his hum etc,coming from the tweeter with your ear up close to it so nothing to worry about.
You probably have already considered these, but just in case you haven't; are you sure you have an odd number of grounded connections? Have you arranged your cables to avoid parallel contact? Do you have adequate distance between components, especially the amp?
Thanks folks
Yes, better shielding on the ICs is definitely something I am considering.
Unsound, what do you mean by having an odd number of grounded connections? Can you explain?
Thanks!
An even number of ground connections is more likely to hum.
.

OK, I'll bite. In 25+ years I've never heard that. Care to elaborate or point to some back up info? Are you talking grounds between components, grounds from component to earth ground, or ??

As to the original post, just quit putting your ear up to the tweeter and everything will be fine.

.
Herman, component to earth ground.
hi,
Thanks all again. Geared4me, that is an interesting thought - I did talk to the Quad folks about this, and they actually said NOT to do that - they said there is a risk that the amp would get overloaded. It was one of the solutions I entertained, and I tried it briefly. While the buzz did not disappear it seemed to get lower. Are you using both the quad link and interconnects without a problem, I gather?
Make sure all your stuff is plugged into the same household circuit. Sometimes by plugging something in from across the room from a plug wired from another circuit of the house will cause this. 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".
There's something Roc said that ought to be a clue, "the buzz is a lot louder if the amp is on with no interconnects hooked up." A ground loop should go away, not get worse when the amp isn't connected to the pre—no connection, no loop. And, a 60 cycle hum should be audible from the other drivers too.

Have you tried another amp? Does it produce the same buzz?
Also: Electronics produce a small but often audible (if you stick your ear right up to the speaker!) noise due to 'quantum noise' in electronics.
ALL electroncis produuce this sort of noise. It may be filtered out, it may be inaudible to some folks or in some combinations, but no matter what, electronics produce this noise artifact. period.
Feel free to argue the point. LOL!
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... ??
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...
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
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
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?
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
Perhaps tightening the tranny (or everything else for that matter) to the chasis of the amp might help?
I bought my pair from Walter at Underwood Hifi and he suggested it so I contacted Quad and they said it would work just fine because the link would pass the control for on/off and the amp would default to the rca input when a signal is detected. This same information was also stated in a review that I can't seem to find right now
Al....I've been doing plug reversal for about 40 years with never having an "incident" as you suggest.
Geared4me, I saw the same review - I think it was the Stereotimes. It is very possible that Quad will automatically give you a response that is in line with their legal liabilities etc having to do with tested safety configurations. I would tend to trust Walter - he knows what he's talking about. I will try that again, but last time it did not abolish the buzz, sadly.
It seems that several folks are suggesting not to worry about said buzz, so I'll live with it if it doesn't go away.
Quick update: I remember why I didn't do the Quadlink and interconnects at the same time - makes the buzz a lot louder!
Damn it, now it's like an annoying puzzle. There is definitely something here that has something to do with the connections and insulation at the input-output area, no?
Does it mean anything that the left channel has a louder buzz, and the speaker connection to it is closer to the interconnect (and quadlink) connection area on the amp?
Stringreen, FWIW, my Threshold manual specifically warns against doing what your suggesting.