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Topic:
Is it normal for speakers to lightly hum?
This thread has 11 replies. Displaying all posts.
Post 1 made on Monday September 16, 2013 at 17:28
kcorona
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I have speakers in zone 2 and a denon avr-2311ci. Sonance speakers are hooked up to the zone 2. Even when zone 2 is turned off on the denon, when the volume on the wall control for the speaker is turned up, it hums slightly. Do you know why that is? In order to shut it off I have to turn down the volume on the wall controls in each room.

Any help would be appreciated!
Post 2 made on Wednesday September 18, 2013 at 09:02
TRCGroup
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Does it still do it when the Denon is unplugged?

If so, the the cause is most likely that your speaker wire is running to close to an electrical line inside your walls.

If not, then it may be a problem with the Denon or your speaker selector, (which you didn't mention that you have).
"You can't fix stupid."
Post 3 made on Thursday October 3, 2013 at 02:17
Ernie Gilman
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On September 16, 2013 at 17:28, kcorona said...
I have speakers in zone 2 and a denon avr-2311ci. Sonance speakers are hooked up to the zone 2. Even when zone 2 is turned off on the denon, when the volume on the wall control for the speaker is turned up, it hums slightly.

Define hum. Most of us think of hum in electronics as a constant tone of only one frequency. If I hum a tune, then I present changing frequencies in rhythm (all right, just close to in rhythm).

Does the hum come from the volume control or from the speakers? I mean, put your ears near both -- which is humming?

Do you know why that is? In order to shut it off I have to turn down the volume on the wall controls in each room.

Depends on the type of hum.

If it's a constant single tone, then that's likely 60 Hz hum which
a) should be present when Zone 2 is turned on, but you might not be able to hear it then if the music is louder than the hum; and
b) should disappear when you turn the volume down then, too.

This one is not likely to be your problem, but I'm just mentioning it: If it's basically music but only the lowest tones of it, that could happen if Zone 2 was on and playing LOUD but the speaker volume controls were turned all the way down. It would come from the volume control itself. This is cured by turning down the Zone 2 volume at the receiver.
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 4 made on Friday November 22, 2013 at 00:12
Tom Ciaramitaro
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What if the hum is 120Hz? Does that change everything?
"People almost invariably arrive at their beliefs not on the basis of proof but on the basis of what they find attractive." - Blaise Pascal
Post 5 made on Thursday November 28, 2013 at 02:37
Ernie Gilman
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Please come back and talk to us!
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 6 made on Sunday December 22, 2013 at 12:45
cctv_hamster
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It sounds like your speaker volume control in the wall is picking up mains radiated hum through close proximity wiring.
Post 7 made on Friday February 21, 2014 at 21:10
Ernie Gilman
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On November 22, 2013 at 00:12, Tom Ciaramitaro said...
What if the hum is 120Hz? Does that change everything?

My description of hum versus buzz was a non-technical way of dealing with sine waves versus other wave shapes. If you try to make the sound mmmmmmmmm and keep your mouth closed, that's hum. If you try to make the sound eeeeeeeeeee with your cheeks pulled back, that's more like buzz.

I think of hum as being a sine wave -- there's 60 Hz and nothing [much] else. If you rectify 60 Hz, you get 120 Hz, but it's no longer a sine wave. Instead it's two half-sine waves in the time of one 60 Hz sine wave. The sharp transition of voltage change at zero volts adds LOADS of overtones to the waveform, and thus it can't be hum; it's now buzz.

You can also have 60 Hz buzz if you distort the waveform. The waveform of voltage across a neon bulb will be 60 Hz buzz; 60 Hz audio run through an amp until the amp clips gives you buzz, too.

The original problem sounds impossible, by the way. I'm reminded of the guy who had small speakers for a few years, then bought a subwoofer. He called a bit later to complained that it hummed.  I had him try some things while he was on the phone and it hummed, no matter what, including being unplugged from the wall and from the system.  I went to his house and determined that since he had bought the subwoofer he was carefully listening for low frequency sounds and he was now noticing, all the time, the refrigerator in the kitchen on the other side of the wall from his small speakers.  He was focused on low frequency sounds and suddenly heard something he had ignored for at least five years.  We have to be careful what we think we hear.

When I explained it to him, it was sort of a "what are you going to believe, me or your own two perfectly good ears?" moment.
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 8 made on Monday March 3, 2014 at 08:32
Daniel Tonks
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I've been fooled by low sounds before. Most recently I thought the air conditioner outside my bedroom was erratically creating a low frequency hum that I could only hear when I sat in a certain spot near the window.

Well, it turned out to be the add-on hard drive for bedroom DVR, which was inside a wooden cabinet and drumming its normally inaudible spin vibration throughout the cabinet - and yet could only be heard if you were in a very small cone directly in front. Added a bit of padding between the two, and no more problem.
Post 9 made on Friday March 7, 2014 at 16:06
Ernie Gilman
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These things are very nice for people to know about, as it makes them look really really sharp when it comes up again, not to mention helping us get over thinking we're going crazy.
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 10 made on Wednesday March 12, 2014 at 22:45
Herman Trivilino
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On March 3, 2014 at 08:32, Daniel Tonks said...
- and yet could only be heard if you were in a very small cone directly in front.

So much for that claim that low frequency sounds are non-directional!
Origin: Big Bang
Post 11 made on Thursday March 13, 2014 at 03:09
Daniel Tonks
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On March 12, 2014 at 22:45, Herman Trivilino said...
So much for that claim that low frequency sounds are non-directional!

The noise itself was generally non-directional, but the ability to hear it in the first place definitely was directional. I remember wandering around the room, trying to pinpoint where it was coming from and finding that very difficult - not because it was everywhere, but because it could only be heard in such a limited area... and when I could hear it, I couldn't tell where it was actually coming from!

The directionality probably had to do with there only being a single wooden door in front of the drive, but a ton of cabinet to the left, at least 5 layers of wood on top, and a wall to the right. Kind of gave me a "cone of annoyance".
 
Post 12 made on Sunday March 23, 2014 at 20:49
Herman Trivilino
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Low frequency sounds, say down around 100 Hz or so, will have a wavelength of about 3 meters or so. Standing waves in the room could easily create a "cone" of a width somewhere around that length, give or take an order of magnitude.

This is why some home theater layouts use two subs. It cuts the chances in half that you'll have these annoying nodes.
Origin: Big Bang


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