Discuss Eliminating subwoofer hum/buzz in the Home Media Centre Forum area at ElectriciansForums.net

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@Midwest
I'll definitely try this

@marconi
N-E shows 0v with mains switch on or off.
None of the appliances affect the noise at all.
Sub is on RingFC up+down.
I also tried the sub with all MCB off except for that 1 socket just to exclude any potential noise from other devices in the house - still no luck.

I will see what the tech support say

In the meantime I'll relax listen some AC⚡DC "noise"
 
I was similarly disappointed with Hum+hiss from a Hi fi loving mates new sub.
(and now fully understand why the diagram has placement of Sub -behind the listener -( and covered in a curtain !))
 
Prompted by Static Zaps #22 I pondered the physics of the low frequency sound from your sub woofer. The speed of sound in air is about 350m/s so a 50Hz sound wave has a wavelength of about 7m. This wavelength is much longer than the dimensions of your sub woofer speaker and box meaning the sound it emits is largely omni-directional. However, being comparable to the dimensions of your room there may well be the effects of constructive and destructive interference between sound bouncing off your walls, floor and ceiling. Such interference for a steady 50Hz tone will produce stationary regions/directions of peaks and nulls in sound amplitude. Where you normally sit in relation to the sub woofer may well be in a peak accentuating the 50Hz hum - you said it sounded less in the showroom. I wonder then if you might experiment with the position of your subwoofer in relation to the walls and the listener. Corners will be good reflectors so perhaps try locating the woofer away from them. Lastly, maybe put some sound absorbent material behind the sub woofer - a curtain? - so the predominant sound is from the speaker towards the listener than from reflections off near walls behind it. So, some trials. Top end Hifi buffs will be able to provide their experience on locating speakers and room acoustics.
 
I've had this on 2 subs now. Neither of which are particularly cheap. One of which I still own and it still does it.

I have a few ideas to try out, but it's not yet bothered me enough to do so.

Mine sounds very similar to yours:
  • Lighting/appliances etc etc make no difference
  • It's done it in two different houses - very similarly
  • The sub is double insulated
  • I've tried plugging all into same lead etc and it made no difference
The only thing that seems to help is if I touch the sub metal casing whilst simultaneously touching the tv metal casing (also double insulated) it gets a fair bit quieter. Unplugging the TV doesn't help! Touching something that is earthed doesn't help. I think touching the bluray player or amp at the same time may have helped a bit too but can't remember now.
 
Based on mattg4321's helpful #27 I'd try bonding the casings of all equipments together so they all share the same ambient earth potential at 50Hz.
 
@Midwest
Tech support come back today but not much of a help, basically try to plug it in somewhere else to double check and if still buzzing take it back.

Also did not post on the forum from the link but did read lots of post there about same problem and tried few solutions but din not get anywhere.

@mattg4321

Seems like excacly same issue.
Did you try to connect it to isolated transformer or some power conditioner or even shaver for testing purpose?


I may try to link the casing of the amp and sub, in my case is all build in so won't see any cables.

What's bothering me is that this is second unit (first one was from Amazon and did excacly the same thing) and this one was plug in in the store and I could not hear anything. On the other hand they may have all equipment connected through some kind of power conditioner.
 
The last one I had that did this was about a decade ago and I'm pretty sure I returned it for a replacement and it did the same thing!

I seem to remember the humming stopped on my current sub for a few months maybe a couple of years ago, then started again.

I'm pretty sure it's something to do with earth potentials as @marconi has been alluding to. I'm not sure its a 'fault' with the sub. More that its some kind of design error that makes them do this under some circumstances i.e. supply voltage/quality differences from one place to another.
 
Human hearing is easily distracted ,
( take a sound level meter with you )
.. Shop test only needs to be a little noisier
and in a wide open space !
..could compare by taking it outside..
Power supply is some of cause ...
but it will be a bit ,dangerous + expensive to run from
batteries !
 
@Midwest
Tech support come back today but not much of a help, basically try to plug it in somewhere else to double check and if still buzzing take it back.

Also did not post on the forum from the link but did read lots of post there about same problem and tried few solutions but din not get anywhere.

@mattg4321

Seems like excacly same issue.
Did you try to connect it to isolated transformer or some power conditioner or even shaver for testing purpose?


I may try to link the casing of the amp and sub, in my case is all build in so won't see any cables.

What's bothering me is that this is second unit (first one was from Amazon and did excacly the same thing) and this one was plug in in the store and I could not hear anything. On the other hand they may have all equipment connected through some kind of power conditioner.

In that case (sounds like a product design problem), I'd send it back & claim a refund. Purchase from a different manufacturer.
 
If it hums when there's nothing plugged into it (aside from power), then it's almost certainly defective - or just poor quality. Ground loops from different earthing potentials are created when you're feeding unbalanced audio signals powered from one supply into a sub powered from another. If you're just plugging it in, switching it on and hearing buzz with nothing else connected, then something's wrong!
 

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