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Old May 22nd 18, 10:04 AM posted to microsoft.public.windowsxp.general
Paul[_32_]
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Posts: 11,873
Default O.T. Speakers static/humming

Mark Twain wrote:
I don't have headphones, a walkman
or iPod etc. to test and the speakers
are brand new Harman Kardon (after the
electrician fried all my components)

https://www.google.com/search?q=Harm...lboe9gT-etK1M:

When I logged on later everything is back
to normal. As I say, it's intermittent.

Robert


Does the Harmon Kardon have a two or three prong plug ?

Computer speakers should have a two prong plug. This
prevents ground loops from forming. The 1/8" plug has
the only ground between the two units, so there's no
ground loop.

If the audio equipment has three prongs, it *might* need
a hum-breaker, which is a form of transformer coupling
between units. These require precisely constructed
transformers for best results (some of these have
a bandwidth of 10KHz or so, not that impressive).

You can also solve hum problems, by using stuff
like TOSLink between units (optical interconnect,
red LED light flowing over plastic large aperture
dental fiber). You would have to look at the input
options on the HK speakers, to see if there's another
way to get there (a way that avoids this stuff).

I've never really owned any "spectacular" audio gear,
and 1/8" audio input is about as fancy as anything
I've had on my gear here. I didn't even have S'PDIF
to play with.

*******

I've had your problem, between my Mac G4 and the stereo
I used for other sources. And the Mac G4 was the only
one with funny radio station noises, hum and other
garbage. I never managed to fix that. While it's
possible to couple radio station signals into audio
cables, and have them rectified by the front end of
the speaker or stereo, it's hard to say why
this happens. I could use the same cable between
two different audio sources, have the problem on
one source and not the other.

Lots of devices in the room with you, use capacitors
on input and output for DC blocking. This is supposed
to prevent one device from applying a DC input to
a transistor on the input of another device, and driving
it into a non-linear area of operation. If you look
at the sound chip on the computer motherboard, it
uses capacitors on all inputs and outputs for this
reason. A defective capacitor might cause a problem,
but when it happens identically on both left and
right channel, you have to wonder whether it's
a design issue.

You could also move audio with something like Bluetooth,
but the default profile for audio isn't all that good.
And that would also add latency, which might upset lip sync
while watching movies.

Paul
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