PC noise through internal sound card - Page 2 - diyAudio
Go Back   Home > Forums > Source & Line > PC Based

PC Based Computer music servers, crossovers, and equalization

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 29th May 2013, 12:32 AM   #11
wwenze is offline wwenze  Singapore
diyAudio Member
 
Join Date: Mar 2008
It is definitely something to do with the grounding.

I have an STX and a DX. Both cards measure nicely as they are known for in loopback mode. But if I let them measure each other, I get an SNR of only ~100dB and affected by computer activity. Same pattern (looking at the spectrum) can be seen in USB DACs and SPDIF DACs without an isolated SPDIF connection. If I use a sound card with transformer for SPDIF output to connect to an SPDIF DAC, then I get the ~120dB SNR (or somewhere there) that the DAC is capable of.

(The onboard sound also measures around that value with similar noise floor spectrum. Makes me wonder, if this noise is suppressed, onboard sound might actually be at the same level of sound cards.)

Optical out into a DAC would be your best bet at minimizing noise. Otherwise depending on the grounding configuration of the DAC/amp (or speaker) that noise may or may not show up, and you got unlucky this time. I once recommended somebody using studio monitors and USB DAC to "play cheat" and lift the ground on the speaker's power socket (along with the necessary warning that this is entirely not safe and should not be used for normal operation) and that did the trick.

P.S. I'm using Antec Truepower New

Last edited by wwenze; 29th May 2013 at 12:40 AM.
  Reply With Quote
Old 29th May 2013, 08:12 AM   #12
Kev06 is offline Kev06  England
diyAudio Member
 
Join Date: Oct 2006
Location: Derby, UK
Quote:
Originally Posted by Wombat View Post
Some easy way for noise coming thru is the front-panel connection. They are often badly or even non-shielded. Did you connect it in your case to the SC?
I've not actually used the front panel connectors - TBH I forgot it was an option. I just connect direct to the back of the card.

Thanks for the thought though,

Cheers
Kev
  Reply With Quote
Old 29th May 2013, 08:35 AM   #13
Kev06 is offline Kev06  England
diyAudio Member
 
Join Date: Oct 2006
Location: Derby, UK
Quote:
Originally Posted by wwenze View Post
It is definitely something to do with the grounding.

I have an STX and a DX. Both cards measure nicely as they are known for in loopback mode. But if I let them measure each other, I get an SNR of only ~100dB and affected by computer activity. Same pattern (looking at the spectrum) can be seen in USB DACs and SPDIF DACs without an isolated SPDIF connection. If I use a sound card with transformer for SPDIF output to connect to an SPDIF DAC, then I get the ~120dB SNR (or somewhere there) that the DAC is capable of.

(The onboard sound also measures around that value with similar noise floor spectrum. Makes me wonder, if this noise is suppressed, onboard sound might actually be at the same level of sound cards.)

Optical out into a DAC would be your best bet at minimizing noise. Otherwise depending on the grounding configuration of the DAC/amp (or speaker) that noise may or may not show up, and you got unlucky this time. I once recommended somebody using studio monitors and USB DAC to "play cheat" and lift the ground on the speaker's power socket (along with the necessary warning that this is entirely not safe and should not be used for normal operation) and that did the trick.

P.S. I'm using Antec Truepower New
Very interesting - many thanks indeed!!!

I'd assumed that (as I was clearly hearing computer activity) it wouldn't be simply a grounding issue. But from your measurements it looks like I'm probably very wrong in that assumption! It also confirms that just using the S/PDIF (or USB) may not necessarily solve the problem as I'd imagined.

Presumably the optical out would completely overcome ground loop problems? I haven't chosen or built a DAC yet so, with a bit of planning that would be a very easy solution. I seem to recall that the STX has a similar spec for both optical and coax so it should be comparable quality hopefully.

I also understand the method of isolating/floating the signal using a transformer, which would get over the need for a DAC. But I've not actually tried this in Hi-fi audio and never on a digital output. Can anyone suggest what sort of transformers should I be looking at?

Many thanks
Kev
  Reply With Quote
Old 29th May 2013, 08:47 AM   #14
diyAudio Member
 
Join Date: Feb 2013
Pulse PE 65612, or Murata DA101MC, or Newava S22083.

You should match impedance on both sides. Usually it is 75R but it seems some experst prefer 100R. And a zobel to correct the transformer.

S/PDIF Digital output
__________________
  Reply With Quote
Old 29th May 2013, 11:23 AM   #15
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
impedance matching is nothing without the cable and connectors all matching the same impedance, as well as termination at the PCB on both ends. thats the last thing to worry about.

what you describe is called blitter-noise and is caused by the graphics processors (GPU) generally, when writing 2D graphics to the screen, which is at lower frequency and this is rectified by chips internal diode junctions, as well as ripple imposed on ground by same.

its conducted primarily through the air, inductively and capacitively, so that it can also be induced on cables. its primarily common mode, but not all. use optical connection, transformer coupled spdif,or isolated USB to avoid it.

Last edited by qusp; 29th May 2013 at 11:25 AM.
  Reply With Quote
Old 29th May 2013, 12:09 PM   #16
diyAudio Member
 
Join Date: Jan 2013
Location: UK
I have a couple of PCs going atm. Main PC uses an Asus rampage gene 4, micro ATX with shielded and separate ground plane'd audio card. Really notice the difference between that and a cheap Asrock MB I had before. Both of these were on an OCZ 1KW PSU. The PSU makes a difference too, as I believe what you're hearing is also loading / ripple.

I also have a Biostar T-power X58 coupled with a Corsair 850W PSU on the other PC, and that's as ripple / noise / hiss free as I can hear; I'm listening to that rig with a homebuilt LM3886 "gainclone" driving JBL infinity 6x9s. (yeah I know. I'm upgrading bits as I go. Built it out of what I had laying around)

In short, you could try another PSU before you consign the whole thing to the bin
  Reply With Quote
Old 29th May 2013, 12:11 PM   #17
Kev06 is offline Kev06  England
diyAudio Member
 
Join Date: Oct 2006
Location: Derby, UK
Excellent - thanks very much for helping me understand this! I've learnt a new term too - 'blitter-noise' isn't one I've run across before.

There does seem to be a definate correlation between whats happening on-screen and the pitch of the noise so it matches what you say about graphics card activity really well. Its encouraging to hear that its likely to be an ambient/environmental type effect, it sounds less fundamental and potentially more solvable than direct electrical problems.

Okay then I'll either try the transformers (observing also the various line impedances) and/or the optical connection and see what happens. The optical one is sounding simpler at the moment, and I quite like it for other reasons too - without ground loop and electromagnetic issues it may be worth looking at repositioning my pre-amp (and/or new DAC) to make the digital optical path longer and so keep any other electrical/analogue cabling shorter. My TV also has an optical output, so I could make/but a DAC that can act as a sort of optical hub or pre-amp.

Thanks again,
Kev
  Reply With Quote
Old 29th May 2013, 12:14 PM   #18
Kev06 is offline Kev06  England
diyAudio Member
 
Join Date: Oct 2006
Location: Derby, UK
Quote:
Originally Posted by TheGabbleDuck View Post
I have a couple of PCs going atm. Main PC uses an Asus rampage gene 4, micro ATX with shielded and separate ground plane'd audio card. Really notice the difference between that and a cheap Asrock MB I had before. Both of these were on an OCZ 1KW PSU. The PSU makes a difference too, as I believe what you're hearing is also loading / ripple.

I also have a Biostar T-power X58 coupled with a Corsair 850W PSU on the other PC, and that's as ripple / noise / hiss free as I can hear; I'm listening to that rig with a homebuilt LM3886 "gainclone" driving JBL infinity 6x9s. (yeah I know. I'm upgrading bits as I go. Built it out of what I had laying around)

In short, you could try another PSU before you consign the whole thing to the bin
Thanks - I'll keep that in mind in case the optical/isolated approach doesn't work. IIRC my corsair SMPS is the 850w version so probably from what you say about your other PC perhaps I have something not too bad to begin with, though. More by luck than judgement in my case!

Cheers
Kev
  Reply With Quote
Old 30th May 2013, 10:55 AM   #19
diyAudio Member
 
Join Date: Jan 2013
Location: UK
Noooo! I listened to my speakers closely. I can hear noise artefacts from my 2nd PC as well now! lol! Can't hear anything from >1ft away at quiescent though.
  Reply With Quote
Old 30th May 2013, 11:05 AM   #20
marce is offline marce  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Location: Blackburn, Lancs
You will probably hear something through most speakers that close.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
How to set up an internal sound Card? AndrewT PC Based 36 24th April 2013 10:31 AM
Internal TT sound card rwm8088 PC Based 4 16th April 2010 05:25 PM
Crackling Noise in Tube Amp (only) & PC Sound Card LinuksGuru Digital Line Level 3 17th May 2009 04:45 PM
Crackling Noise in Tube Amp (only) & PC Sound Card LinuksGuru Tubes / Valves 3 17th May 2009 04:44 PM
Internal sound card change to external? EmergencyDpt Digital Line Level 4 31st August 2008 06:57 PM


New To Site? Need Help?

All times are GMT. The time now is 07:23 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2