burbeck wrote:
On Wed, 5 Jan 2005 19:29:36 -0000, "Stimpy"
wrote:

OK, I'm asking this on behalf of a friend with no ng access so be
gentle with me if this is a really stupid question!

He's got a Quad 33/303 based system and wants to connect his laptop
to it to play mp3s. He tells me that everything works fine when the
laptop is on battery power but as soon as he plugs in the power
supply, there's a loud humming audible through the stereo speakers.

It's obviously something to do with the presence of the mains power
but what can he do to stop it?

hi yes i agree its a ground loop, good cheap and simple cure is
available from maplins ground loop isolation transformer this is 2
transformers in one (stereo) comes fitted with phono plugs and sockets
on short wires these plugs will have to be changed or adapted to suit
your equipment Maplin code VW43W, cheap enough to give it a try around
£7
regards
bob

Thanks... Message passed on... He's going to give this a try. Might not be
the most elegant solution but if it does the job it'll be fine.