PC audio noise

Luck100

I've got a pair of studio monitors connected to my desktop PC. I'm getting a varying level of screeching/electronic noise coming out of the speakers - loud enough to be quite noticeable when I don't have any music playing. The noise is clearly related to stuff happening inside the computer - it changes in sync with mouse movements and starting/stopping certain software. It gets quite a bit louder running some 3-d graphics applications.

I've tried using the motherboard sound output as well as a USB dac (Behringer UCA202). The USB dac is better but the noise is still there. I don't get any noise at all when I try running the speakers with a portable music player.

Anybody have any suggestons? Would a different USB dac be any better? I have optical output on my motherboard sound card, but optically-driven outboard dacs seem to be rare these days. The speakers are active bi-amped, so I assume the noise must be entering via a ground loop when I use the USB dac.

Luck100

Bump.

Would be interested in hearing from anyone running PC -> DAC -> powered speakers. Problems or no problems.

art

Run a fiio DAC and a Line6 (for different purposes) from the PC, (and also have a discrete sound card and also have onboard audio as it happens!!). I would output to different headphones and to powered speakers: no problems anywhere. Onboard audio can easily pick up interference so that wouldn't be a surprise but the DAC should isolate it so that's a bit odd alright - do you hear it with headphones plugged into the DAC?

Luck100

No noise/interference with headphones plugged into motherboard audio or external DAC.

I tried cutting the ground loop circuit path by running the speakers with the grounding pin disconnected (using a plug adapter for the power plug). That completely got rid of the noise, so I'm convinced the problem is a ground loop between the powered speakers and the PC. Obviously it's not safe to run always the speakers without grounding, so I'm going to try an audio transformer box between the dac outputs and the monitor inputs. They're supposed to safely cut the ground loop circuit.

What are your powered speakers (brand/model)? Perhaps they have some kind of input isolation that prevents ground loops. It's also possible my PC generates more electronic interference as it's primarily a gaming machine, so there's a lot of high-wattage parts in there.

Luck100

A quick update: I installed a behringer hd400 and it's eliminated all the noise when I use my external dac. The hd400 sits between the line outputs of the dac and the line inputs of the powered speakers.

art

I apologise, I meant to come back earlier and update because what I had said about my setup was wrong, I have two sets of speakers and missed saying that there is an audio switch box after the DAC in the chain - completely forgot about that until I sat down to do some recording on Sunday. Anyhow, good you've got it sorted now!