Using a computer with a stereo system - mains interference?

[admin_exported]

I've just linked my laptop up to my stereo (Quad 33 preamp, tuner input) via a jack-to-DIN lead. The sound is perfect when the laptop is running on battery power, but on mains power there is an unacceptable level of crackling when it's plugged into the two closest sockets to the stereo (a third socket, across the room, produces minimal crackle provided the plug is pushed in hard). It doesn't seem to matter whether the sockets have any other load on them, and the interference is the same regardless of which input is selected on the amp or the level the volume control is turned up to.

I've never experienced this problem when playing my computer through my DAB-CD radio. Incidentally I'm not using a DAC, and the computer's mains transformer/charger has an earthed supply.

Any thoughts gratefully received!

 

[John Duncan]

Yep, my laptop power supply makes an awful racket. Using an external DAC or soundcard to take the audio away from the badly-screened laptop power supply will help, or alternatively look at streaming audiousing an airport express, squeezebox or similar.

 

[Anonymous]

John, many thanks. I've found fix I remembered from years ago, which is to remove the earth pin from a multiplug and plug the computer in through that (a mains filter might do the same job). Might also try a DAC though I'm thinking of upgrading to a Quad 99CDP2 before too long, which has a DAC built in.

Stan