Electromagnetic Noise in Speakers

Thread Starter

JohnJohnto

Joined Jul 6, 2020
7
Hi all,

I'm looking for a bit of advice. I have just moved into a new house and am experiencing constant EMI (think that mobile phone interference) in my Yamaha NS7s. It is constant and is present once the speakers are turned on, even without any connections. I have troubleshooted a number of things:

1. The EMI is only present in my room. Plugging in the speakers in the other bedroom in the house and all other areas (living room and kitchen) has resulted in silent speakers, not the constant interference.
2. As stated above, it is not an issue related to balanced or unbalanced cables, as the noise is present even when disconnected.
3. The EMI is present from both plug sockets in the room, whether connected to an extension lead or directly in.
4. Using a long extension I could also rule out a grounding issue. Connecting to a socket is an adjacent room the EMI was not present, but came back when walking with the speaker into my room.
5. Turning off Wifi in the house and anything else I could think of made no difference at all.

So, I am at my wit's end with this. Apart from not being shielded by design, the speakers work absolutely perfectly.

I am wondering if anyone has any advice on how to get rid of this noise from the speakers. Putting tin foil around them has made little difference. For clarity, it is a small house at the end of a terrace in a city centre.

Also, the fact that this interference seems only to be in my room (I sleep here too) has made me a little worried healthwise. As far as I know, there is no proven health risks regarding EMI though.

Cheers for reading this.
 

MrChips

Joined Oct 2, 2009
23,221
Welcome to AAC!
Check to see if there is a light dimmer switch in your room or anywhere in the house.
Also look for a touch sensitive table lamp.
 

Wolframore

Joined Jan 21, 2019
2,255
Some LED lights are noisy due to their switching power supplies with poor shielding. See if turning off the lights change the noise.
 

Thread Starter

JohnJohnto

Joined Jul 6, 2020
7
Thanks for the replies. The constant EMI is present in the speakers when everything else in the room is plugged out and switched off. There are no LED light bulbs or faders either. It is an old build house. However, what confuses me is that the EMI is only present in my room, nowhere else in the house. In terms of where the room is located, it is under the attic and there is another house the other side of one wall. The cause could be in one of these areas I guess. The noise is present when mobile is turned off too. It's a very constant thing in the speakers.
 

Alec_t

Joined Sep 17, 2013
11,998
It is possible that the mains power sockets in that one room have no effective ground connection. I'd get that checked by a competent electrician.
 

Thread Starter

JohnJohnto

Joined Jul 6, 2020
7
It is possible that the mains power sockets in that one room have no effective ground connection. I'd get that checked by a competent electrician.
I had thought about that. So I got a long extension lead, brought the speaker into the bedroom next door and plugged it in there. It was silent. I then carried the speaker into my room and the interference started again. So, I deduced from that that the sockets in my room were not the issue.
 

OBW0549

Joined Mar 2, 2015
3,566
However, what confuses me is that the EMI is only present in my room, nowhere else in the house. In terms of where the room is located, it is under the attic and there is another house the other side of one wall.
So I got a long extension lead, brought the speaker into the bedroom next door and plugged it in there. It was silent. I then carried the speaker into my room and the interference started again.
The constant EMI is present in the speakers when everything else in the room is plugged out and switched off.
I would conclude from these observations that the interference is not coming from anywhere in your house, but rather from the unit on the other side of the wall.
 

Thread Starter

JohnJohnto

Joined Jul 6, 2020
7
I would conclude from these observations that the interference is not coming from anywhere in your house, but rather from the unit on the other side of the wall.
I'm thinking along those lines. I've just moved in and don't know the neighbours at all. It's very possible that there is something the other side of this wall like a fader light or LED lights or anything along those lines. It's a terraced house and there wouldn't be too much space between houses. Is it possible that something in between the walls could be causing it?

I guess if that is the case, there is nothing I can do about it. My speakers are not shielded. Would anyone have any advice on how to shield them? Tin foil made little difference. With regards to health risks, I've done a bit of reading and the consensus seems to be that any fear about health risks is just that - fear. There are no proven health risks and a lot of the concerns seem to be putting 2 and 2 together and getting 5.
 

OBW0549

Joined Mar 2, 2015
3,566
It's very possible that there is something the other side of this wall like a fader light or LED lights or anything along those lines.
That would be my guess.

Is it possible that something in between the walls could be causing it?
Possible, I suppose, but my first candidate for the culprit would be what you suggested above.

My speakers are not shielded. Would anyone have any advice on how to shield them?
I can't think of anything you could do except making sure you're using shielded cables for the speakers' audio inputs-- which you probably are.
 

Thread Starter

JohnJohnto

Joined Jul 6, 2020
7
That would be my guess.


Possible, I suppose, but my first candidate for the culprit would be what you suggested above.


I can't think of anything you could do except making sure you're using shielded cables for the speakers' audio inputs-- which you probably are.
Would Ferrite beads or anything like that on the power cables make a difference?
 

OBW0549

Joined Mar 2, 2015
3,566
Would Ferrite beads or anything like that on the power cables make a difference?
I doubt it. When you plugged in the speakers in the other bedroom, the quiet one, the noise only appeared when you carried the speakers into the "noisy" room. That suggests to me that the interference isn't being conducted through the power cables.
 

Thread Starter

JohnJohnto

Joined Jul 6, 2020
7
I doubt it. When you plugged in the speakers in the other bedroom, the quiet one, the noise only appeared when you carried the speakers into the "noisy" room. That suggests to me that the interference isn't being conducted through the power cables.
Thanks. Good point. I guess the only way to sort it is to find the source, shield the speakers in some way or get new speakers
 
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