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Do power supplies make a difference when using coax from sound card?

71.221.87.7
Posted on July 23, 2012 at 04:19:34
progression
Audiophile

Posts: 30
Location: Coast of Oregon
Joined: August 23, 2006
 I have been looking at the excellent ripple measurements of some select Seasonic products. When using the coax only out of my Xonar ST or STX sound card, will I hear a difference if I am using a nicer Seasonic Gold series Power Supply or will a cheaper one sound just the same? I do not want to pay up if the sound quality is not "clearly" heard. I have quite a resolving system so very minute changes play roles, but I've just been curious how a nicer PS would make the sound better than a "fine enough-aka Seasonic Bronze series say" power supply.

Thanks for recommendations and all input on this one.

 

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Well, posted on July 23, 2012 at 07:29:09
Gordon Rankin
Manufacturer

Posts: 2701
Joined: June 9, 2000
 Prog,

There are really 2 problems you face. One is since this is the driving end the amount of noise in the computer supply is going to effect the jitter on the reference clocks and all the associated drivers. The amount of ground noise and switching noise from a computer can be really devestating to a sound systems.

Secondly if you are not galvantically isolated from the computer then your analog rig will take on all that computer noise from the ground connection.

Thanks
Gordon
J. Gordon Rankin

 

RE: Do power supplies make a difference when using coax from sound card?, posted on July 23, 2012 at 08:03:19
fmak
Audiophile

Posts: 9177
Joined: June 1, 2002
 Of course!

 

ASUS (at least Essence ST)) gives you the ability to use power SEPARATE alltogether ..., posted on July 23, 2012 at 09:24:19
carcass93
Audiophile

Posts: 5490
Location: NJ
Joined: September 20, 2006
 ... from computer PSU.

For best sound quality, you absolutely have to use quality linear regulated power supply, just for the sound card. Attaching Molex connector to such power supply is the easiest 10 minute DIY project.

 

Yes and no..., posted on July 23, 2012 at 12:15:11
Presto
Audiophile

Posts: 5112
Location: Canada
Joined: November 10, 2004
 The molex connector powers part of the card, yes (probably DACs, audio codec, op amps, etc.) but the PCI/PCI-e data I/O is still powered from the computer AFAIK. Not saying it's not worth doing, it just means that part of the card is powered by one supply and part by another. I would be concerned, too, with having a floating voltage between the two ground planes of the PC supply and the linear supply.

What voltages are you running to the card? 12VDC/5VDC?
Which supply did you get?

I have always wanted to do something like this.

Cheers,
Presto

 

For me it was D2X, with "floppy-style" connector., posted on July 23, 2012 at 13:01:29
carcass93
Audiophile

Posts: 5490
Location: NJ
Joined: September 20, 2006
 I'm pretty sure that the following applies to the newer ones too:

You're right about basic IO functions working off MB power anyway (LEDs too, BTW). The separate power line has to have +5V if you're only using SPDIF, and both +5V/+12V if using analog.

If it's not connected, SPDIF out works off MB power, and I'm pretty sure analog out would not work at all. If it IS connected, then SPDIF and DAC circuitry works off that additional power.

You can clearly hear relay click fraction of second after external power is turned on. Very easy to test for sound quality between two modes.

I used variable-output bench power supply - gives you an advantage of lowering/increasing voltage a little, to test an effect on sound. Don't remember now what setting worked best though.

 

RE: Well, posted on July 23, 2012 at 14:14:55
progression
Audiophile

Posts: 30
Location: Coast of Oregon
Joined: August 23, 2006
 So are you suggesting that anything inside a computer is going to be faulty due to noise UNLESS one deals with it all OR goes to say, a galvanically isolated USB async converter? I'm trying to understand what you are saying here about all the noise problems and the best solution to get around them if that involves not using a sound card all-together?

Thanks

 

RE: For me it was D2X, with "floppy-style" connector., posted on July 23, 2012 at 14:20:34
progression
Audiophile

Posts: 30
Location: Coast of Oregon
Joined: August 23, 2006
 1) What kinda of diy or can you even make one for me or show me details on a well done PS for the 5V section of the card?

2) If the 12V's then only deals with relaying the info (i.e. information from motherboard/pc to card), would it even still make sense to have a superior 12V supply on the computer itself or would that become unimportant or irrelevant so long as the computer is working just fine?

I can see how a solid 12V's would be necessary for use of the analog portion, but being that I will use only the digital section, seems I can get away with a decent enough PS for 12V's, then power the 5V's with whatever you recommend especially if it's diy=shouldn't cost much of anything.

 

RE: Well, posted on July 24, 2012 at 07:03:57
Gordon Rankin
Manufacturer

Posts: 2701
Joined: June 9, 2000
 Prog,

I have developed basically 8 motherboards since 1990. Of those several were used for high volume production. Therefore I had to test these boards and see how they preformed and what kind of noise to expect.

Now the biggest problem is not the power supply but how cheap these companies are. I designed one motherboard that was built into about 1.8M PC's. When I designed that I had 2 cost accounts strapped to my desk and I battled with them over the littlest of things.

The noise on the back plane of any computer is crap. So then you take something like PCI and convert it to high speed serial interface like PCIe and it get's worse. The ground noise is terrible on this stuff.

So basically what I am saying is keeping things outside is much better. Maybe you can find a board that is galvanically isolated and is powered externally and that would be your best bet.

There are tons of USB to SPDIF boards out there. Really if you go USB why bother with SPDIF at all, it sucks it never worked really well and if you can do USB DAC that is designed well, then it will out perform any SPDIF counterpart.

Thanks
Gordon
J. Gordon Rankin

 

RE: For me it was D2X, with "floppy-style" connector., posted on July 24, 2012 at 08:44:31
Presto
Audiophile

Posts: 5112
Location: Canada
Joined: November 10, 2004
 I was going to ask about a relay. Not sure if that would be for on/off bump supression or if it routes power based on the molex power supply connection. Ineteresting. Yes, I did read in your D2X manual that you *need* to have the molex connected for the card to work. My old X-fi also had the molex but IIRC, I ran with the molex disconnected most of the time and the card worked. I will have to revisit this... haha. Too bad there are no sockets on the X-fi to roll op-amps. The ones they use are cheesy.

Yes, I looked at "DIY"ing various PCI soundcards by analysing the PCI interface only to find the extent to which the computer power inundates these cards. If the card does NOT have the molex connector to supply power to specific (isolated) card components, the redesign effort would be so extensive that it would be better to spend ones time doing their preferred trade and craft and spend the money on an outboard solution.

It's sure fun, though, when you squeeze sound out of PCI solutions that are far better than they are supposed to be.

Cheers,
Presto

 

RE: Well, posted on July 24, 2012 at 15:57:37
telackey
Audiophile

Posts: 229
Location: Oklahoma
Joined: January 15, 2006
 Unrelated, but do you like toslink better or worse than spdif?

I know (or I think I know) that the protocol is similar, accounting for the obvious changes at the physical layer. I was not sure if your complaint about spdif is about that physical layer--which toslink would fix, though it might do something else wrong--or some other issue they would share.

 

RE: Well, posted on July 24, 2012 at 16:02:22
telackey
Audiophile

Posts: 229
Location: Oklahoma
Joined: January 15, 2006
 To clarify, I am not talking about converting USB to SPDIF or Toslink. That does seem kind of strange unless you had a specific requirement for it.

I am asking more generally.

 

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