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Jeff Liebermann Jeff Liebermann is offline
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Default audio buzzing after PC is turned off

On Sun, 13 Jun 2021 09:23:53 -0400, W Pulaska wrote:

Pretty simple set up. I have my phono output from my desktop Audiofile
2496 sound card driving an Altec Lansing speaker set.


OK. That would be a circa 2002 M-Audio Audiophile 2496 PCI card:
https://www.newegg.com/m-audio-audiophile-2496/p/N82E16829121120

Works fine when
everything is on, but when the desktop is turned off I am getting a
buzz/ hum from the speakers and loud enough that I power them off.


One speaker or both speakers?

Is the buzz/hum still there when you turn off the unspecified model
Altec Lansing (amplified) speakers? I'm wondering if the problem is
in the computah or in the amplified speakers?

Why is this and how to remedy? Thanks.


Instead of turning off your unspecified model PC, try unplugging the
AC power cable from the PC to insure that it's really turned off. If
the hum/buzz disappears, my guess(tm) is the WoL (wake-on-LAN) power
from the power supply is making its way somehow to the sound card.
I've fixed one similar "noisy when turned off" PC problem by replacing
the power supply. Unfortunately, I didn't bother trying to figure out
the exact cause.

Does your unspecified model PC also have a built in sound card on the
motherboard? If yes, unplug the 2496, and try running your
unspecified model Altec Lansing speakers from the motherboard sound
(green) output. If the hum/buzz goes away with motherboard sound,
then the problem might be something on the M-Audio 2496 card. To be
sure, try installing a different PCI sound card. If the replacement
PCI card doesn't buzz, then it's probably something on the M-Audio
2496 card.

Do you have a ground loop isolation audio transformer handy? Something
like one of these[1]?
https://www.amazon.com/s?k=ground+loop+isolator+3.5mm
https://www.ebay.com/sch/i.html?_nkw=ground+loop+noise+isolator+3.5mm
I'm not sure what it might mean if installing one of these fixes the
hum/buzz problem, but it would be an interesting test.

Good luck.


[1] I carry some of these in my toolbox. They mostly get used to
break the audio ground loop between the TV earphone jack and amplified
speakers.


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