Speakers passing unwanted tone, frequently

[squishy]

I've been noticing that my subwoofer is passing out a mid to low tone about every 10 seconds for roughly 3 seconds while both in use (sound should be being emitted) and while not in use but still on. This has been going on for a while now (a few months) and I'm really stumped as to why it's happening, or how to remedy it. It's not a really loud noise, but it's very noticeable when I'm not playing music.

I've had the speakers (same model as these but maybe an older version) for quite some time now, possibly approaching five years, and I've not experienced anything like this before.

Anyone got any ideas why it could be happening and/or how to remedy it?

[Dolus]

I would disconnect the signal inputs to the subwoofer and if it still makes the hum then the subwoofer is at fault.

If there is no hum then try different input cables to see if the hum disappears. if it does then the cables were at fault.

If no difference then disconnect all the inputs to the amp. If the hum is still there its the amp at fault. If not then reconnect one input at a time to see if the hum reappears. if it does then that is the item or it's cable that needs looking at.

It might be worth checking your speaker cables. If they are bare wire all it needs is one lose strand touching an adjacent cable to cause a hum.

[squishy]

Ok, thanks for the help, I just spent a while taking out each input one by one, and the sub was silent when all the inputs were attached apart from the DIN cable from my decoder, and as soon as I attached it, the noise was back. However, this confuses me a bit, as the noise is apparent even when the decoder is unplugged from the mains, which leads me to think that something is wrong with either the DIN cable, or the jack into which is goes on the sub..?

Thanks again

[dave87]

Does the DIN cable run past any other cables? Mains, Network etc? They shouldn't cause a problem, but you never know...

[squishy]

How'd you mean 'run past'? The DIN cable only connects the decoder to the subwoofer, if that's what you mean. The decoder runs on a separate power supply from the sub too.

[BenW]

Does the physical cable run along the floor near other cables? Dave is suggesting it could be inteference from other cables

[squishy]

Ah right, it runs with one of the rear speaker cables, and crosses the power for the decoder, and also the input from my PC to the decoder. Though as far as I know it's always been in close proximity to other cables such as these and it's not caused a problem

[Dolus]

It does sound as the DIN cable might be at fault. It might be acting as an ariel picking up hum from adjacent cables or other equipment.

Can you check the plugs on either end of the cable to see if any of the wires have become disconnected.

Trying a different cable would be another option.