[LAU] loud noise out of external soundcard in the bandroom when AC-powered

Hello list,

When playing with my band in the bandroom, I'm recording the whole session
with ardour and playing the phasex resp. zynaddsubfx via a midi keyboard. To
do this, the outputs of my external soundcard (m-audio fast track pro) are
plugged into the PA. Because the sound is very much amplified, an incredible
noise can be heard when no one's playing, approximately as loud as two people
talking (yes, it's very annoying!) - however, yesterday I noticed that this
only happens when my laptop is AC-powered! If it runs on batteries, it's
completely silent and there's no noise in the background.

Now, before I start fiddling around, is this because of a poorly shielded
powersupply? Or is this problem related to the shielding of the laptop? How
can I build an effective shielding?

Greetings
Matthias
_______________________________________________
Linux-audio-user mailing list
Linux-audio-user@email-addr-hidden
http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user
Received on Mon Mar 17 16:15:07 2008