Need Help on Eliminating AC Hum from Computer Audio Feed

[MrBruce]

Hello, I am not sure If anyone else has experienced this problem, but either way, hopefully someone can suggest a way to eliminate the problem.

 

Whenever my audio mixer is connected to my computer (for the automated programming) I get an AC hum in the audio feed. This is noticeable if only the ground side of the mixer is connected to the metal computer casing. Everything in the audio chain is connected to Earth ground one way or another. Either Earth ground is done by the MAINS ground or by a separate ground wire that all the audio equipment is connected to, which goes to a ground rod buried 5 feet in the ground.

 

We tried connecting the 3 conductor audio plug into a separate computer and as soon as the ground makes contact with the computers chassis the AC hum is present, same goes if said plug is plugged into the sound card. It is noticeable enough to register at least 10% on the audio meters and can be heard in the audio carrier, specially if there is no intended audio present in the audio chain.

 

Anyone have any idea how we can eliminate this AC hum?

 

Bruce.

[johny c]

Sounds like you have a ground loop hum. Try using a ground loop isolator in you audio lines

[MrBruce]

Thanks for your reply John.

 

Is this device intended to be inserted into the audio wiring coming from the computer?

 

I know I did not explain my setup very well, as I realize some people feed their programming into a computer and stream their programming on line.

 

Here the computer feeds the mixer, then the mixer feeds the audio processor and then on to the transmitter.

 

We have two turn tables and a microphone on the mixer besides the computer, so my question is should this device only be put in line with the computer to mixer feed?

 

Seems like the computer feed is the only connection that results in the hum.

 

Edited part:

 

I see Radio Shack sells these things and it appears it got some decent reviews.

 

I think your directions would be for me to put it in-line with the computer feed. The one at Radio shack comes with a 1/8" male plug, which is what my sound card requires.

 

Bruce.

[johny c]

Hi Bruce, yes use it between the pc and the mixer. Sometimes you may need to use them on your other lines as well if you still get some hum. I have them on all my inputs on the mixer. The one you found will do the same job. Sometimes you can get a hum if your transmitter is too close to your other gear.