Question : Problem: soundcard hum

I've had this problem for many years on different computers and different Creative soundcards.

I want to run my soundcard through my stereo amp. When I plug the soundcard into the amp, there is a persistent hum from the amp speakers, even if the amp is set to another source.

There is no hum running the soundcard directly to speakers.

Both the amp and the computer are plugged into the same AC circuit, so there should not be a groundloop. Both amp and computer are properly grounded. The cable run is about 6 feet and not over any transformers or other noise source. The cables are of reasonable quality.

The hum can be ameliorated, but not eliminated by jiggling the stereo minijacks plugged into the sound card. This leads me to believe it's a connection issue between the stereo minijacks and the plugs on the soundcard.

At http://members.aol.com/whitfiel/dig_rec.htm a guy talks about solving his noise problems with "trs 1/8 inch plugs on soundcards" using "semiconducting fluid or Craig DeOx". I can find no other reference on the net to either of these mystical items. Ever hear of them?

How can this connection be improved to the point where the hum will go away? Is there some kind of plug-compatible isolation transformer for this problem? It drives me nuts! Am I the only person in the world who plugs  a soundcard into an amp? What does everyone else do about this issue?

Answer : Problem: soundcard hum

A ground loop may indeed be present if both amp and computer are grounded and they are connected through a signal cable (having a grounded shield).

/RID