I wonder if the difference isn't simply that you are running the laptop 
using the external power supply when the audio gets noisey, but that the 
laptop is consuming maximum power under this condition (i.e., it isn't be 
using any power saving or throttling strategies).

This is just another take on the problem, but it may be that there is too 
much electronic noise inside the small space of the laptop, itself, under 
full power conditions.  If this is the problem, it might be solved with an 
external USB sound "card".

John Sproule

--------- Original Messages -----------------

Date:    Mon, 16 Jun 2008 09:14:43 -0500
From:    Dennis Duke <[log in to unmask]>
Subject: Noisy Laptop Power Supply

A friend of mine just purchased a new HP laptop for the express purpose of
playing music at square dances. We discovered that the power supply is
generating noise when he tries to play the music and also when he tries to
copy music from his record collection (old 45's). What can be done other
than running the laptop from its batteries (which won't last long enough for
and evening's music)? There is no ferrite bead on the power supply lead.
Would that help? Any other ideas?

And . . .

Date:    Mon, 16 Jun 2008 14:34:32 -0700
From:    Ericson Russ <[log in to unmask]>
Subject: Re: Noisy Laptop Power Supply

I will be interested in the answer to this. I've noticed the same thing 
playing movies and the noises peg with CPU usage. When I removed the power 
supply the noise goes away.

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