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That noise floor of on-board audio

post #1 of 14
2/9/13 at 8:10pm
Thread Starter 

Dash it all, now I hear the little pops and whirs my computer makes when using the headphone out.  My wallet is starting to cry, on the inside.

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post #2 of 14
2/10/13 at 1:11am
Quote:
Originally Posted by TheNewCanMan View Post

Dash it all, now I hear the little pops and whirs my computer makes when using the headphone out.  My wallet is starting to cry, on the inside.

You're suffering from signal to noise ratio tipping in favour of noise.

Increase the volume on your player to 0db and use the windows volume control to adjust what you hear. If you still need to tweak, control panel will help and remove all enhancements.

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post #3 of 14
2/12/13 at 8:40am
Quote:
Originally Posted by TheNewCanMan View Post

Dash it all, now I hear the little pops and whirs my computer makes when using the headphone out.  My wallet is starting to cry, on the inside.

Mute all inputs, line-in, mic, etc, and try another output, hear or frontal. 

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post #4 of 14
2/12/13 at 8:48am
Does it happen at the same time you are copying files and such?

I found using a properly grounded socket for power helps.

Also, on my desktop system I have an output board on the front of the system, these are very noisy outputs compared to the outputs in the back of the motherboard.

I used a half-decent cable (not one of those $1000+ ones, but perhaps not the $1 one either, just something isolated?) for years with no problems (cheap thin cable = noise, front connectors = noise)

Ofc you can get a USB DAC or something and pretty much forget about it :-)
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post #5 of 14
2/12/13 at 9:20am
Thread Starter 
I have a dgx coming from amazon, we'll see if that helps. I am using the front headphone port for ease of use, but that's going to change from now on. I'll look to see what is or isn't muted and mute everything unnecessary. I do hope to upgrade to an external dac, but that may have to wait a few months.
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post #6 of 14
2/12/13 at 9:24am
Quote:
Originally Posted by TheNewCanMan View Post

I have a dgx coming from amazon, we'll see if that helps. I am using the front headphone port for ease of use, but that's going to change from now on. I'll look to see what is or isn't muted and mute everything unnecessary. I do hope to upgrade to an external dac, but that may have to wait a few months.


Can you try the rear port instead?  I have horrible EFI noise coming through my front port due to the poor quality wires running to them (all cases seem to have really cheap standard wiring with no shielding at all).

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post #7 of 14
2/12/13 at 9:34am
Thread Starter 
yeah, I am going to try that out until the sound card arrives, and then I will plug in to that.
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post #8 of 14
2/12/13 at 10:16am
Quote:
Originally Posted by liquidzoo View Post

Can you try the rear port instead?  I have horrible EFI noise coming through my front port due to the poor quality wires running to them (all cases seem to have really cheap standard wiring with no shielding at all).
No, you had noise because audio ground was connected to the case in your front panel.

Cables don't pick up enough noise to affect headphones. And PCB traces going to rear ports aren't shielded either.
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post #9 of 14
2/13/13 at 5:26am
Quote:
Originally Posted by mich41 View Post


No, you had noise because audio ground was connected to the case in your front panel.

Cables don't pick up enough noise to affect headphones. And PCB traces going to rear ports aren't shielded either.

 

Where ever to connect the audio ground ?  AFAIK,  the mobo ground is always connected to the case, too.

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post #10 of 14
2/13/13 at 2:29pm
ATX cables and mobo ground traces have some small, but nonzero, resistance. Because they carry lots of current returning from various devices to PSU, some small voltage (few millivolts) develops between case and mobo ground and even between different points on mobo ground. To make things worse, this voltage constantly changes with varying power consumption of devices.

When audio ground wire is connected to the case, it starts carrying part of this return current and some small voltage develops across it. Now headphones see different "ground voltage" than soundcard, but signal level remains unchanged, so signal level relative to ground seen by headphones becomes wrong by few millivolts. The exact magnitude of this error constantly changes, producing a new wave "seen" only by the headphones. This wave is the noise you hear.
Edited by mich41 - 2/13/13 at 2:30pm
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post #11 of 14
2/13/13 at 11:23pm
Quote:
Originally Posted by nagual View Post

Where ever to connect the audio ground ?  AFAIK,  the mobo ground is always connected to the case, too.

 

The front panel cable should have a ground wire (pin 2, AGND) that comes from the sound card. The front panel PCB needs to be modified so that the audio jacks are connected to the ground wire of the front panel cable, and no other ground (I do not know why it is not made that way in the first place), and of course not to the case. This can take a few cuts and some soldering to fix completely. While EMI is less of a problem than ground loops, you do also want to keep some distance between the front panel cable and any high current (e.g. power) cables.


Edited by stv014 - 2/13/13 at 11:26pm
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post #12 of 14
2/13/13 at 11:33pm
Quote:
Originally Posted by liquidzoo View Post

 

Can you try the rear port instead?  I have horrible EFI noise coming through my front port due to the poor quality wires running to them (all cases seem to have really cheap standard wiring with no shielding at all).

 

The rear jack may work better, but unfortunately it may be a line output, which is useless for driving headphones.

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post #13 of 14
2/14/13 at 4:50am
Rear usually has both line out and front out/headphone out for recent chips?
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post #14 of 14
2/14/13 at 5:08am
On my MSI 760GM-E51 mobo with Realtek ALC889 HDA codec the rear green jack has slightly less subbass (too small DC decoupling caps, I guess) but it still sound fine for anything non-dubstep smily_headphones1.gif

Other rear jacks are crap, though.
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