[lag0a]

Hi
 
I am wondering if anyone has tried using a PCI-Express to PCI riser card adapter with an external 4 pin power connector for their PCI sound card to isolate the PCI sound card's power from the motherboard. If so, what were your result? Did it improve sound quality using an external power supply?

 

[leeperry]

these boards don't pass 12V, so most serious soundcards won't work. The Prodigy HD2 analog output didn't work, only the toslink did(the DSP feeeds 5V, the opamps voltage regulators 12V).

 

[lag0a]

I thought it would work with any pci card with 100% functionality. Only the toslink part of your sound card worked? Did it improve the sound quality with an external power supply? I only need the coaxial output of the sound card to work so would the adaptor card work for me?

 

[leeperry]

FWIU, PCI board are not supposed to use 12V...most serious soundcards do need it to feed their opamps(most DSP chips need 5V), so those adapter boards don't provide 12V. Can't tell about any SQ improvement, as the SQ over toslink is rather poor IME.

 

[lag0a]

I see what you mean now. I did a little research and it seems my auzentech x-meridian sound card (first generation) uses an +/- 8V dual power supply. Some PCI express to PCI adapter cards with a 4 pin molex doesn't specific 12v but I found one that does. This adapter card specifies 3.3V/1A, 3.3V/100mA, 5V/5A and 12V/500mA but to receive 5v and 12v you need to connect the 4 pin molex to a power supply.

 

[leeperry]

Oh yeah, I used a cheap one...some of them are very pricey, they might indeed provide 12V. But then the additional latency/jitter(due to the bridge) and the price of the adapter, minus the resale of the existing PCI soundcard make it a deal breaker IMHO.

 

[lag0a]

That is the main problem. The latency/jitter in the adapter card with windows plug and play drivers but external power supply vs straight from the motherboard and motherboard power.
Hmm. If the auzentech x-meridian uses +/- 8v dual power supply, does it mean it gets its power from the 5v and 3.3v part of the computer power supply? Does it even need 12v?

 

[leeperry]

It's most likely using the same voltage regulators as the Prodigy HD2, they have a 3V overhead...so you feed unregulated 12V, you get regulated 9V. If I were you, I'd sell that PCI board and get something PCI-E native....this kind of adapter board is nothing more than a kludge IME.

 

[ramicio]

Don't we realize electricity travels at the speed of light?  A few inches of copper isn't going to introduce perceptible latency.  Jitter is between a receiver chip and a DAC.  Jitter is a DAC phenomenon, it has NOTHING to do with sound data being sent to a sound card or over a USB cable.

 

[leeperry]

Those boards use a PCI > PCI-E bridge, jitter will occur...and the boards that pass 12V are pricey FWIR. Plus, you can't securely screw the soundcard into the PC case anymore, so it's hanging there....even low profile boards can't be screwed in.

 

[ramicio]

No jitter.

 

[leeperry]

some companies sell PCI-E jitter attenuators: http://www.datasheetdir.com/874005AG-04LFT+PCI
 
and that's the PEX812(one of the most widely used PCI-E bridge) confidential datasheet: http://www.google.com/url?q=http://wenku.baidu.com/view/4a1d1fb069dc5022aaea00e2.html&sa=U&ei=NFsvTZfTCojMhAfyypHnCg&ved=0CBAQFjAC&usg=AFQjCNFoYOqq0p6WdQEbzGY3hmliwZ98FA
 
"This provides an option for a low-jitter clock"
 
but I forgot, 0's are 0's and 1's are 1's

 

[ramicio]

Jitter in a PCI bus will not affect sound.  The audio data being sent to a sound card isn't right to a DAC chip.  The jitter occurs between whatever the sound renderer chip is and the DAC, not the bus and the DAC.  When everything remains digital 0's are 0's and 1's are 1's.