Speaker box making a constant 'duh..duh..duh..duh..' noise

[Kos]

I've got one of those all in one speaker units for use with my TV, satellite etc.
Whenver I switch it on all I get is the noise described in the question title (sorry but thats the best way I can describe it!)
I can see about 4 speakers in the unit and some small, what used to be called in my day, tweeters.
I have disconnected the unit from all other untis and it still makes the noise.

[ChuckFickens]

if you have anything like a cordless phone or wireless router, or anything else that may be wireless near it try switching that off to see of the noise stops.

[Kos]

None of those I'm afraid. - phones are in another room, as is the wireless router.

[AlBags]

You may have an earth loop problem (like you can get with microphones)
Have you checked all leads or substituted any?

[Kos]

I've tried it standalone AlBags with nothing connected but the mains power and it still makes the noise when it is on. Sounds like a machine gun going off.

[ChuckFickens]

I was going to suggest trying it on a different ring main in your house for the same reasons as the above poster.

[Kos]

Thanks folks. I'll try that as it is sharing a cheapo 4-gang plug socket with other electrical devices.

[AlBags]

Yep ... Try upstains and turn the volume up a bit more!

[AlBags]

TBH .. sounds like power supply problem with speaker amp.