[wplug] sound trouble w/ laptop

DAVID G MATTHEWS dgm4+ at pitt.edu
Wed Sep 5 21:03:50 EDT 2001


There are two potential (and not mutually exclusive) sources of this
problem.  The first is that there is usually little, if any, acoustic and
electrical isolation in laptop sound cards.  This makes it prone to all
sorts of interference from the cpu and disks.  Secondly, you didn't
mention whether or not your 1/8th"-RCA adaptor has an impedance matching
resistor.  If not, then when you take a signal from the headphone out and
connect it to a line-level device, you've got to boost the output get any
kind of audible signal, and you amplify any distortion along with it.
Plus, your signal is at the wrong impedance, which only adds more noise.
You can get an adaptor that has an impedance-matching resistor built in,
and that should do something, but the bottom line is that laptop sound
cards generally aren't that great.
-dgm


On Wed, 5 Sep 2001, coldfire wrote:

> uhh, well .. the computer speakers work fine (as do headfones) .. however,
> when i plug a 1/8" to rca plug adapter into the laptop's headfone jack (no
> dedicated line out) and i run it to any other device (computer speakers,
> stereo, vcr, etc.) i can hear all of the electronic noise from the
> harddrive, the display, the cpu when it's crunching numbers, the dvd-rom,
> etc.  kind of annoying.
>
> i've seperated parts to the best of my ability and haven't been able to
> track down the cause for the noise.  any ideas?  thanks
>
>
> coldie
>
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