Hi,

I am attempting to run the audio output from my computer's soundcard
into the auxilary input on my home stereo amplifier so I can play the
music on my computer throughout the rest of my home. The problem is
that as soon I patch the cable into the auxilary input there a wicked
hum starts up on my home stereo system that nothing I try can get rid
of. Some one told me to run a single wire between the metal casings of
the computer and amplifier so they are grounded with one another. I did
this however it didn't change much. Any ideas would be greatly
appreciated.

Thanks,
YYY

Yeahyeahyeah wrote:
Hi,

I am attempting to run the audio output from my computer's soundcard
into the auxilary input on my home stereo amplifier so I can play the
music on my computer throughout the rest of my home. The problem is
that as soon I patch the cable into the auxilary input there a wicked
hum starts up on my home stereo system that nothing I try can get rid
of. Some one told me to run a single wire between the metal casings of
the computer and amplifier so they are grounded with one another. I did
this however it didn't change much. Any ideas would be greatly
appreciated.

Thanks,
YYY
Are they plugged into the same AC circuit in your home?
If not, try an extension cord so the power comes from the same source.
If this cures it then you need to isolate the ground on the audio cable

from the 2 devices or power from the same power source.

Try putting the amp in the same room, on the same outlet, as the computer.

Also try reversing the amplifier's plug in the wall outlet. (This might not
be possible, if the amplifier has a grounded plug, or if the plug is
polarized. If it is, don't try to defeat the ground or the polarization.)

On 1 May 2006 04:10:32 -0700, "Yeahyeahyeah"
wrote:

I am attempting to run the audio output from my computer's soundcard
into the auxilary input on my home stereo amplifier so I can play the
music on my computer throughout the rest of my home. The problem is
that as soon I patch the cable into the auxilary input there a wicked
hum starts up on my home stereo system that nothing I try can get rid
of. Some one told me to run a single wire between the metal casings of
the computer and amplifier so they are grounded with one another. I did
this however it didn't change much. Any ideas would be greatly
appreciated.

Get an isolating transformer.

Yeahyeahyeah wrote:

I am attempting to run the audio output from my computer's soundcard
into the auxilary input on my home stereo amplifier so I can play the
music on my computer throughout the rest of my home. The problem is
that as soon I patch the cable into the auxilary input there a wicked
hum starts up on my home stereo system that nothing I try can get rid
of. Some one told me to run a single wire between the metal casings of
the computer and amplifier so they are grounded with one another. I did
this however it didn't change much. Any ideas would be greatly
appreciated.

Your problem is due to too many ground paths, not too few. there is a
nice discussion of ground loops in the FAQ, but the short answer is that
an audio isolation transformer will be your real solution.

Unless you have a cable TV line attached to the stereo, in which case
lifting the cable line ground is probably easier.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Getting Older and Grumpier Gear Minion wrote:

snip

If this cures it then you need to isolate the ground on the audio cable

NO !

You need to 'isolate' the *signal* ie use a 'DI box' for example.

Graham

"Yeahyeahyeah" wrote in message
ups.com...
Hi,

I am attempting to run the audio output from my computer's soundcard
into the auxilary input on my home stereo amplifier so I can play the
music on my computer throughout the rest of my home. The problem is
that as soon I patch the cable into the auxilary input there a wicked
hum starts up on my home stereo system that nothing I try can get rid
of. Some one told me to run a single wire between the metal casings of
the computer and amplifier so they are grounded with one another. I did
this however it didn't change much. Any ideas would be greatly
appreciated.

They call this a "ground loop." It's a result of different ground
potentials on 2 different pieces of equipment. The usual culprit is a cable
TV connection, which is grounded somewhere other than the place the rest of
the system in grounded. Current flows between them and the result is hum.

Try 2 things. 1. Be sure the computer and the stereo system are plugged
into the exact same outlet. 2. Disconnect the cable TV if there is one.
One or the other of those solutions almost always works.

Norm Strong

Norm Strong answer is right, it is a ground loop, that's clear but it
should'nt have anything to do with the power-socket or the earth
potential there. Since stereo-units are not grounded, and TV's as well
does'nt have a ground, so the earth of the power-socket is not
responisble for that hum. That hum causes from the ground-connectrion
between your computer and your stereo. I think, you use a longer cable
for it, right?

You have two technical ways to kill the hum.
First, place your PC next to your stereo-system and use short cables
max. 1,5mtr - the hum will leave your house without return.
Second, you replace you soundcard to one with balanced outputs and use
an line-transformer at the stereo-side. The balanced
system prevents you from any hum at all. The transformer steps down and
back to the stereo-connectors (red/whitre). This is
the professional solution and works without any problem. Thousands of
studios are working like that.

Have some fun and success
Frank, Soundland Music (Germany)