[lug] audio interference question

[Matt James]

In my experience, computer audio (not just laptop) has always been quite
noisy from a recording standpoint because of all the EMI running around
inside the box.  The only way I've got 100% away from this is to go to a USB
or Firewire audio I/O.  Now, I've always done this on a Mac or a Windows PC
so I'm not sure about linux compatibility, but you might want to consider
something like this:

http://www.guitarcenter.com/PreSonus-AudioBox-USB-2X2-USB-Recording-System-243007-i1388074.gc

Best of luck, I've spent many many hours trying to chase down noise sources
in a scenario like this.

Matt

On Thu, Jan 29, 2009 at 8:35 PM, karl horlen <horlenkarl at yahoo.com> wrote:

> i plugged the stereo out of my laptop into a really nice power amp /
> speaker combo i normally use for recording.
>
> when the laptop is NOT plugged in (running purely on battery), the sound is
> pristine... exactly what i'm looking for.  fwiw, i made sure i've muted the
> microphone to eliminate any extraneous sound.  if i don't do that, you can
> hear whitenoise when no music is playing.. probably picking up internal
> drive and fan noise..
>
> here's the catch.. the minute i PLUG the laptop in to POWER IT (non
> battery), i get a an annoying but constant static / hum / interference
> sound.  it does NOT go away, even if i totally mute the sound on the laptop.
>  so it's electrical in nature.
>
> i've tried plugging the laptop in all of the outlets that are within reach
> of the power amp.  buzz / hum / static is still there.. it sounds like a
> motor or something and or possibly even acting as an antenna...
>
> the odd thing is i've got another pc and 3 other audio gadgets that are
> hooked up to this same power amp and none of them have this this same
> issue.. pristine sound.  so i can't think it's a grounding problem in the
> house or circuit.  only the laptop plugged into the wall outlet generates
> the hum.
>
> i tried unplugging all other devices on the power strip, nothing helps.
>
> - is there anything i can do to make this work with power?
> - any test to eliminate the problem (though my tests are already telling me
> fairly clearly that the laptop (psu or brick?) itself is the source of the
> problem)?
> - are laptops or their psu / bricks known to not be grounded or shielded
> very well?
>
> thanks to anyone that can unlock the mystery.  i'd like to make the laptop
> i have rarely ever used become my full time mp3 / media player.
>
>
>
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