[lug] audio interference question

[Matt James]

>
>
> I suspect that the problem will still be there. If so, it's not a
> ground loop. In such a case the problem is (somewhere) in the power
> supply of the laptop, not being enough "clean" for audio purposes. If
> that would be the case, you might have some luck changing the power
> brick, but don't take it for granted.
>
>
This is what I was getting at in my initial response.  In my experience,
laptops don't have a "ground" or if they do, it doesn't go all the way to
the laptop.  In that case, it's hard to get a ground loop problem.
(Although I have seen plenty of that in a regular ole PC.)  I'm guessing
there is something noisy in the brick and/or the internal power supply that
just doesn't get used when it's on battery.  So back to my original
suggestion of getting an external I/O device that does the A/D outside of
the noisy environment.  I actually poked around and found a less expensive
device for $30.  Sure beats spending $100 on a new brick only to have the
same problem.  I guess it depends on what you're trying to accomplish.

MJ
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