Buzzing noise

[Kev]

Can anyone help please.When I play my laptop or mp3 player through the sound system at a venue I do, I get a loud buzzing noise.If I take the mains power supply out and use the laptop or mp3 on their batteries the buzzing disappears.
This has been happening for weeks now but I have only just tried taking the plugs out.
I could use both just on their batteries but some weeks I do about 4 hours with my laptop ( I don't use my mp3 when doing more than a couple of hours).

[Bernie]

That sure sounds like a grounding problem. I once encountered this with my audio gear and computer and the solution was simply to run a wire from the metal casing of my DAT machine to something that was grounded in the room.

[canadiantire]

Q1. Was the problem there before or has is started doing the buzz suddenly?

• If the problem appeared over the time, there might be a bad ground connection somewhere.

Q2. Is the Laptop plugged in the same power receptacle as the sound system?

• If not, try to do so.

The Laptop power adapter could also be defective or there may be a break in continuity of the ground connection to the laptop.

• Make sure that the wall receptacle is properly wired.I admit that this is not an easy one but I know that some hardware stores carry an inexpensive test plug to confirm the integrity of the receptacle connections (i.e.: live wire, neutral wire and ground wire).

• Try the same setup at a different location and see if the problem goes away.

If after all these checks you can't find the source of the buzz, there is a device called an audio isolation transformer that is specially designed to eliminate this kind of trouble called a "ground loop".

I can be found in specialized audio shops or car audio stores (chances are that your local car audio carry it as a stock item).

It is usually inexpensive.

Be careful, if the audio isolation transformer is from a bad quality, you will fix the buzzing noise but you may experience loss of high frequencies.

This device is to be installed between the laptop cable and the RCA connectors of the amplifier (see attached image).

full size here:

Keep us posted on your troubleshooting!