Speakers "humming"

therecklessone

This is really annoying...

I've noticed a low frequency humming noise coming from a couple of speakers in my room. My stereo speakers, and the set attached to my computer are both at it, even when they are switched off (but still plugged in).

Its been suggested to me it could be an earthing problem.

Any thoughts?

silverside

yes sounds like bad earth. I had a similar problem coming from an NTL cable into my hifi whenever it was connected to the tv. Try making an extra earth by connecting one piece of cable into the earth pin of a 3 -pin plug, leave the others unconnected, and attach the earth to some metal part of whatevers humming.

WARNING do this at your own risk (not that theres any risk if you do it right).

robbie1876

Most likely it is an earthing problem alright. You say you have a couple of sets of speakers in your room. Are the computer speakers and the stereo amp connected to different power sockets in the room? You probably have the stereo and the computer connected somehow, to feed the computer sound through the stereo speakers? Can you try disconnecting this lead and see if the problem goes away?

If it does go away after you do this, the next thing to try is to get all the audio and PC stuff onto the same extension plug from the same socket. It is possible that the earth problem is being caused by running the different pieces of equipment off different spurs from the fusebox, which can cause problems.

Also, do you have a TV tuner in your PC, or do you have a TV hooked up to your stereo? If so, try disconnecting the aerial lead and see does the problem go away. Cable TV is a major source of earth problems, but can easily be sorted with an earth isolator.

Let me know if any of this is any good to you!

Robbie

therecklessone

Thanks for the suggestions folks.

I had a brainwave earlier that it might be caused by poor quality 4-way extension plugs, so tried plugging the stereo into the actual plug socket. Still noise.

However, it was when I got closer to the stereo to check that I realised the noise is coming from the stereo itself. Its a Sony Hi-Fi (Model CMT-CP505MD), and there doesn't appear to be any noise coming from the speakers themselves, just the Hi-Fi.

Now that I've realised that, I'm tempted to think that there wasn't any noise coming from the PC speakers, but I was just hearing things in my rather annoyed state...:D

Anyway, can I just assume that the stereo will continue to p*ss me off? Is it "supposed" to make this noise?



Robbie, the stereo and computer aren't connected in any way. I've got a 5.1 set-up throught the PCs soundcard. The stereo has two speakers of its own.

PC + Subwoofer from 5.1 set-up are attached to one 4-way extension.

Stereo attached to another.

Both extensions are plugged into a double wall socket.

Ta.

robbie1876

Bizzare. The noise is coming from the hi-fi itself? It's obviously loud enough to annoy you, so there must be something seriously wrong with it. Does the hi-fi function ok, as normal? And does the sound come through the hi-fi speakers at all?

Sometimes the power transformer within the unit can hum, perhaps this is the problem. Leave the hi-fi on for a while then feel around the back where the mains lead goes in. Is it excessively hot?

It now sounds like it's not a mains earthing problem if you've eliminated those other things. Can you double check the PC speakers to see if that hum is there too? If it is, try unplugging the hi-fi from the mains and then listen again to the PC speakers.

We'll get you sorted eventually!!

Robbie

therecklessone

Right, I'm *nearly* sure there's no unusual noise out of the PC. I've already tried the stereo switched off and I couldn't pick up any sound from the PC

Hi-Fi works fine, I've not had any performance problems with it. This "noise" is really noticeable at night (when there's no background noise to mask it), so as I'm trying to drift of to sleep I can hear it. Now I'm like a dog with a bone once something like this becomes obvious, so its getting on my nerves. Simple answer would be to unplug the thing every night I suppose.

Hi-Fi has been on about an hour now, virtually no heat from the back where the mains goes in.


And thanks for your persistence.

John R

Many electronic devices can have an audible hum, I have come across several of them, and I mean equipment without fans or other moving parts. My ntl box has a distinct buzz/hum when on but not standby, an old satellite reciever did the same but in reverse; noise in standby, quiet when on!

robbie1876

John R is right, some devices have noisy transformers and there's not much you can do about it. In your case however, it sounds like this is a fault which has developed over time and is now really getting on your nerves. I would be fairly sure at this stage that your step down transformer in the hi-fi has developed a fault, and that replacing the transformer would be the only way to sort it out.

If its under guarantee, get it back to the retailer straight away, if not, there's a place called the Hi-Fi hospital on Capel St (not sure if the shop is still there though) that fixes this sort of stuff. Get an estimate first.

Or else just unplug it at night if the noise is not a problem during the day!!

Robbie