[PointyFox]

Does anyone know how to reduce noise over the PCI bus or get audio out of a computer without it being contaminated by GPU/HDD EMI?  Here's how it sounds:
 
Sound card/RCA (with significant amplification): hummmmm
Sound card/front panel:  HUMMMM crack HUMMMMM bzzt
Ipod plugged into USB:  BZZZZZZZZZZT CLICK CLICK CLICK CLICK WHIRRRRRR CLICK CLICK CLICK WHIRRRRRR
Ipod running on battery (with significant amplification):   .  .  .
EMU 0202 DAC plugged into USB:  BZZZZZZZZZZT CLICK CLICK CLICK CLICK WHIRRRRRR CLICK CLICK CLICK WHIRRRRRR
 
I tried a ground loop isolator, but that doesn't do anything to the noise over the audio signal.

 

[swmtnbiker]

Do you have an el cheapo Chinese power supply in your system? If so then replacing it with a decent PSU might be a good way to go. You might want to take a look at your case fans too.

 

[PointyFox]

 
Quote:

Do you have an el cheapo Chinese power supply in your system? If so then replacing it with a decent PSU might be a good way to go. You might want to take a look at your case fans too.

 
Sí, es hecho en China. I have a "Dell XPS 630 / 630i 750W Power Supply - DW002 / H750E-01".

 
Why would I want to look at my case fans?

 

[swmtnbiker]

Good old proprietary Dell. Your PSU options are very limited. As for the case fans, cheap/old ones with defective motors can sometimes bleed EFI.

 

[PointyFox]

I'm sure it's HDD/GPU EMI.  I hear HDD clicks/seeking, and moving the mouse/screens/flash animations make distinct noises.

 

[swmtnbiker]

A problem that systemic is not good. You even get it with an external USB DAC? I'd almost be afraid to strap something on my head that's connected to that PC. The PSU still seems like a good suspect to me since everything is connected to it.

 

[zoso947]

It's almost certainly a power supply problem, knowing Dell one of the caps is probably blown.  That PSU does have standard ATX mounting holes though, so you should be able to replace it.

 

[Uncle Erik]

PC Power & Cooling (www.pcpower.com) has replacement PSUs specifically for Dell units. I've been using their PSUs for awhile and have been very happy with them.

 

[leeperry]

Is your wall outlet grounded? anyway, you need to source a USB Isolator if compatible w/ your audio interface...you're experiencing the computer dirty ground making it to your audio ground, which should be null.

 

[Arctia]

I'd be wary of buying any newer pc power and cooling power supplies. They were bought by OCZ and all original employees got fired. OCZ, needless to say, does not have a stellar record when it comes to power supplies.

 

[Uncle Erik]

I'd be wary of buying any newer pc power and cooling power supplies. They were bought by OCZ and all original employees got fired. OCZ, needless to say, does not have a stellar record when it comes to power supplies.

Thanks for the tip - I had no idea. I'm glad that the PCP&C supply I picked up about five years ago is still going strong.

Who is building a good supply today? Getting into audio took me out of the computer market. One of the boxes is a 2.0GHz Athlon64, single core. It runs well, but am thinking about putting something newer in there.

 

[sonci]

what do you mean by significant amplification",
if you have a heavy power amplifer, then its normal that when you crank up you hear the hum, even with the best soundcards,
if its at listenable levels then check the hardware..
 
Quote:

Does anyone know how to reduce noise over the PCI bus or get audio out of a computer without it being contaminated by GPU/HDD EMI?  Here's how it sounds:
 
Sound card/RCA (with significant amplification): hummmmm
Sound card/front panel:  HUMMMM crack HUMMMMM bzzt
Ipod plugged into USB:  BZZZZZZZZZZT CLICK CLICK CLICK CLICK WHIRRRRRR CLICK CLICK CLICK WHIRRRRRR
Ipod running on battery (with significant amplification):   .  .  .
EMU 0202 DAC plugged into USB:  BZZZZZZZZZZT CLICK CLICK CLICK CLICK WHIRRRRRR CLICK CLICK CLICK WHIRRRRRR
 

I tried a ground loop isolator, but that doesn't do anything to the noise over the audio signal.

 

[Trapper32]

I found this to be an interesting site  http://cicsmemoryplayer.com/  They seem to think the Antec EarthWatt is a good psu.  Think I will be building something along these lines soon. 

 

[jla]

Quote:

I'd be wary of buying any newer pc power and cooling power supplies. They were bought by OCZ and all original employees got fired. OCZ, needless to say, does not have a stellar record when it comes to power supplies.

I've used an OCZ StealthXStream PSU for a year with no problems...

 

[PointyFox]

Quote:

what do you mean by significant amplification",
if you have a heavy power amplifer, then its normal that when you crank up you hear the hum, even with the best soundcards,
if its at listenable levels then check the hardware..
 

 

Enough that if I plugged an iPod in on max volume, it would destroy my headphones.  I'm a perfectionist 

.   It's definitely not a defective PSU, as I've tried 3 others in the same model.