Audio interference (ground loop?)

alex24 · 28 Mar 2010 at 02:35

Using both front and rear audio outputs from my motherboard, there is a horrible high pitched interference. If I change the audio settings from headphone to front speakers, it reduces, but is still very much present. It's totally distracting and makes listening to anything using decent headphones or speakers annoying.

It also seems to respond to mouse movement.

I've tried unplugging everything attached to the machine, USB, DVB-T aerial, video etc, but none of it makes any difference.

I'm using a Gigabyte MA78GM-S2H 780G motherboard. I have the latest audio drivers, though changing makes no difference.

I think perhaps there's some sort of ground loop going on, and I've tried to narrow it down as much as possible.

One thing I haven't tried is disconnecting the front panel audio.

Any other ideas or suggestions for getting rid of this problem?

BloodyL · 28 Mar 2010 at 02:41

I always thought the ground loop issue presents itself as a low hum (50-60hz) rather than high pitched noise.

Obvious fix #584: have you muted all incoming signals, usually Line In or Mic In can dump a load of noise in to the system.

Oh, and I think you might be better getting the thread moved into the Sound Card section of the forum.

alex24 · 28 Mar 2010 at 03:04

BloodyL said:
I always thought the ground loop issue presents itself as a low hum (50-60hz) rather than high pitched noise.

Obvious fix #584: have you muted all incoming signals, usually Line In or Mic In can dump a load of noise in to the system.

Oh, and I think you might be better getting the thread moved into the Sound Card section of the forum.

I guess they could be harmonics, my setup won't present much audible low frequency sound.

I'll try muting the signals too, forgot about that, thanks.

Also, on the contrary, most threads in GH get a much better response as a lot more people browse in here. I guess it's not exactly the right place and a bit selfish, and if a mod wants to move this they can.

EDIT: Muting all other channels, and also the muting the channel headphones are in, showed no change whatsoever.

DigitalReaper · 28 Mar 2010 at 09:36

alexhull24 said:
It also seems to respond to mouse movement.

Sounds like your sound card is picking up interference from various sources inside the PC. A seperate decent sound card _may_ help, either internal or USB.

You'll still have the problem on the front panel connector if you go the USB route though as there's no way to connect it up, but it's more likely to solve the problem IMO.

alex24 · 28 Mar 2010 at 10:49

I do think a dedicated card would resolve the issue, though I'd rather avoid having one since it would really impede airflow in the case. I only have one PCIE slot left and it would sit right between the passive gfx and cpu cooler.

I'm going to try and disconnect the front panel to see if it's picking it up there and I'll report back!

alex24 · 28 Mar 2010 at 11:20

OK, so I've removed the cable to the front panel connectors, but I'm still getting terrible interference.

Not sure where to go from here.

DigitalReaper · 28 Mar 2010 at 15:33

USB? (see my previous post)

alex24 · 28 Mar 2010 at 17:03

DigitalReaper said:
USB? (see my previous post)

I'd rather avoid buying a separate external sound card. Perhaps I'll take the opportunity to look into upgrading my sound to something that accepts a digital connection, which I don't *think* would suffer from this problem.

Do you think it's grounds for RMA if it won't go away, or is it likely to do with how my case is connected/grounded?

wonko · 28 Mar 2010 at 17:35

I had a motherboard a few years ago (an asus a7n8x deluxe) which was known for the on-board sound picking up buzzy/squealy noises which changed with CPU load and when moving the mouse etc. Very annoying it was too.

Only thing I can suggest trying is enabling spread spectrum options in the bios. A different psu might help, but if the source of the noise is the VRMs on the motherboard it might be a long-shot.

adrichardson81 · 28 Mar 2010 at 18:20

Have you tested with a different set speakers/cans?

alex24 · 28 Mar 2010 at 18:50

wonko said:
I had a motherboard a few years ago (an asus a7n8x deluxe) which was known for the on-board sound picking up buzzy/squealy noises which changed with CPU load and when moving the mouse etc. Very annoying it was too.

Only thing I can suggest trying is enabling spread spectrum options in the bios. A different psu might help, but if the source of the noise is the VRMs on the motherboard it might be a long-shot.

Good suggestion, I'll try it out. There are a few spread spectrum options in the BIOS.

adrichardson81 said:
Have you tested with a different set speakers/cans?

Yeah, it happens with my 5.1 speakers (all via 3.5mm jacks) and with my headphones (connected via 3.5mm jack). The slightly odd thing is, when I select 'headphones' on the jack sensing popup when the cable is plugged in, the problem is a lot worse than when I select 'front speaker'. This is regardless of which jack I plug into. I don't *think* it's a software issue, but this must then be a symptom relating to where on the board the interference is coming from.

skippy2421 · 28 Mar 2010 at 23:10

i've got this exact same issue at the moment however it only seems to happen with my speakers bizarrely as my headphones don't seem affected. Mine also seems to change with the mouse too. Keep us informed as to how you get on as i'd love to find a solution to this too. I've checked my cable routing and everything but i just can't solve the darn thing.