PC peripherals adding noise to amplified audio

[BobCharlie]

I'm running a MSI 990FXA-GD80 board with a decent audio card. Sound is outputted via S/PDIF Digital Audio Coax Cable to a digital to analog converter, which enters an external EQ and then an external amplifier.

I first noticed some line noise years ago which was traced back to an older, wired laser optical mouse. Unplugging that mouse made the signal noise went away. I eventually opted for a modern wireless Logitec micro mouse that uses a different laser system (not the red laser, it might be infrared or something as no visible light is emitted).

Anyways, if listening through external speakers, I can't hear anything unwanted. However, with headphones connected, there's a constant blipping sound (it very quiet but obvious on dead silent audio tracks like silence in a movie) that's semi irregular. On rare occasions it stops, only start back up a second later and it's very annoying.

I've tried unplugging the modem, unplugging the blue tooth adapter for the mouse, physically turning mouse off, unplugging the key board, and nothing is working. Sometimes while using the mouse, the sound will seemingly "attach" itself to what the mouse is doing. Like say clicking a sentence and dragging mouse cursor to highlight it, the sound will be affected.

I'm fairly patient, but the sound is getting annoying and ruining the headphone experience and I'm not sure how to stop it? I'm thinking a ground issue? Ideas?

 

[TbsToy]

That sounds like noise is being introduced somewhere in your analog chain, not the PC. Maybe the audio jack.
As a test do you pick up noise when connecting directly to the mobo out for the headphones?
W.P.

 

[BobCharlie]

LOL, ^ you are on the ball my friend. I actually just tried this, and it's extremely quiet i.e. no back ground noise or unwanted interference bleeding through to the headphones.

I could leave it like this, but even with the several enhancements via win7, it's lacking some punch.

What would you suggest if I want to keep using an external amplifier?

 

[TbsToy]

Tough call. Something in the analog chain is the issue. Digital is noise free, analog isn't. 1s and 0s ya know. You have to isolate the component that is introducing the noise and without an oscilloscope that is difficult other than swapping out individual components til you find the offender.
What I do is run Wasapi in the OS to a compatable player like Foobar or Cyberlink to a HDMI out of the Graphics card to a A/V receiver to a big JBL 5.1 system with Eq management. Don't know if this helps or not.
Maybe more questions?
W.P.

The Sennheiser HD 600s play flawlessly through the A/V reciever headphone jack, (Yamaha Aventege), with great clarity and plenty of volume. Ditto for the JBL's

Analog ain't all it is professed to be by the tuber marketing types.
Digital is here to stay.

 

[BobCharlie]

OK, unplugged the amp's RCA's from the digital/analog converter, noise went away. Plugged back in, then unhooked the digital coax input to converter, sound went away again, ruling out converter (thankfully). Thinking the digital coax might have poor shielding, I switched to a heavy-duty GE digital coax with thick shielding that had never been used before, and the sound persisted, but was a tad less pronounced but still there. Disappointed but not ready to give up, went ahead and switched to the optical PC out instead, and dead silence!!


Running off the amp again and headphones sound as quiet as they did connected directly to the 3.5mm jack on PC front. I can't even detect ANY sound via the amp now on audio silence unless I turn volume up above 60%, which even there it's still less than the noise introduced from the coax. No hum, no hiss, nothing at normal to moderate levels. Super excited. And here I thought the digital coax was better. There sill might be a ground issue or noisy AC, or something sending interference out the coax couldn't get away from, but amazingly the optical out is completely blocking it.


Thanks for pointing me in the right direction TbsToy! The actual digital coax was the last thing I'd have expected to be faulty (or PC out is faulty) as I was thinking it was either a ground issue or or due to all the wires. I seriously can't emphasize how much noise was removed from the audio path now. Absolutely quiet! Can finally enjoy my new headphones and listen to music or watch movies w/o that awful distraction. Thanks again!

 

[TbsToy]

Great! Digital coax is really analog. Fiber optics, pure digital, worked. A happy camper now.
W.P.