[Dick Baker]

For many years, I've piped audio between my stereo gear (which includes a
couple of DAT decks) and my PC with S/PDIF (both optical and coax) using an
M-Audio DiO Delta 2496 sound card in the PC. That card bellied up on me,
and while I figure out what to get next, I tried connecting the PC's built-
in sound card to the stereo preamp with regular audio cables--but got a
60Hz hum.

That didn't surprise me too much, although the outlets for the stereo and
PC are in the same room, on the same wall, just 6' apart, but to be safe &
sure I used a short extension cord to connect the PC's UPS to the same
outlet as the stereo--and to my surprise, got the same hum.

Now what? Is is possible for the UPS to create a different ground
potential from the outlet into which it's plugged?

--
--------------------------------------------
Dick Baker
(contact via http://goon.org/newcontact.php)

[Scott Dorsey]

Dick Baker wrote:
For many years, I've piped audio between my stereo gear (which includes a
couple of DAT decks) and my PC with S/PDIF (both optical and coax) using an
M-Audio DiO Delta 2496 sound card in the PC. That card bellied up on me,
and while I figure out what to get next, I tried connecting the PC's built-
in sound card to the stereo preamp with regular audio cables--but got a
60Hz hum.

That didn't surprise me too much, although the outlets for the stereo and
PC are in the same room, on the same wall, just 6' apart, but to be safe &
sure I used a short extension cord to connect the PC's UPS to the same
outlet as the stereo--and to my surprise, got the same hum.

Now what? Is is possible for the UPS to create a different ground
potential from the outlet into which it's plugged?

Yes, but the problem is less apt to be the UPS than a connection to a
cable TV system with a different ground.

Audio isolation transformers are your friends. But an isolation transformer
for the cable line is probably cheaper.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Arny Krueger]

"Dick Baker" wrote in message

For many years, I've piped audio between my stereo gear
(which includes a couple of DAT decks) and my PC with
S/PDIF (both optical and coax) using an M-Audio DiO Delta
2496 sound card in the PC. That card bellied up on me,
and while I figure out what to get next, I tried
connecting the PC's built- in sound card to the stereo
preamp with regular audio cables--but got a 60Hz hum.

So drop into the nearest Radio Shack and pick up their under-$20 ground
isolator.