[Magsy]

I'm talking about the PCI 0404 which has KS.

That Teradak looks naff. There is only one good solution via USB and that is the Hi-Face.

Re-reading the thread it appears you are basing your issue of 'noise' on analogue outputs via your onboard sound card; stop right there and try a real output device.

 

[leeperry]

oh no, I'm not...I was getting a very loud groundloop hum over a Prodigy HD2 Advance PCI soundcard w/ RCA over an external Burson HA-160 headamp, and also from the onboard..basically my computer ground is hopeless, the hum was changing depending on the graphic card activity.

I also get random ticking on my uber-sensitive headphones, whatever directly connected to a PCI soundcard or a USB audio device...just like this guy explained he got over firewire: FireWire 4-wire cable to break "ground loop" - mLAN Forums

Building a PSU for an external firewire soundcard - diyAudio
Quote:

The firewire optical isolator is basically optical isolation for firewire device. So there is no ground loop flowing between your soundcard and the PC (PC ground is extremely dirty).

ok, interesting! so KS on XP is automatically bitmatched too? the hiface is...but the teralink doesn't do KS on XP, and I need it for Reclock and ASIO4ALL

and I still dunno whether the hiface has a transf. on the coax..

 

[Magsy]

I still think you are barking up the wrong tree. Onboard is not even worth talking about the the HD2 is not the greatest. With digital out you are not going to get analogue issues such as hum, it is digital signal. Jitter or dropout maybe...

I have a PC with three 15k scsi drives, two 10k sata drives, a high end scsi raid card with its own 600mhz cpu, 4 gb ram, two Emu 0404's, a tv tuner and a cpu that is overclocked to twice its original frequency paired with a big gpu. Analogue or digital, coax or optical I don't have any issue. I have used all the kit in my sig with it at one time or another in the last five years and all performs noise free. I have a $5 four gang socket plugged into the wall and the kit on that.

I also have a 12v SLA powered 'PC' that has nothing but a copy of Win XPE, Foobar and an Emu 0404; to me it sounds no different to my main rig.

Rather than trying to work around the issue, if it is that bad then it needs to be fixed not hidden.

The Hi-Face has a transformer : M2TECH Hiface USB->SPDIF 24/192Khz asynch - diyAudio

Also if you have a card that does ASIO then I don't see why you need anything else, you don't need ASIO4ALL (fake ASIO) on a pro card that supports it natively.

 

[leeperry]

indeed, but I need KS for Reclock on XP anyway...and I like ASIO4ALL, it's a very smart KS wrapper...it's always nice to have options, because for instance the ASIO drivers for the 0404USB are quite buggy as they were not coded as virtual devices...and after each reboot you have to reselect them in foobar, very annoying!

well, there is indeed some soundcards that have a very efficient ground shielding like the Asus STX and the Auzen Bravura...and they use different grounds for the audio path and the chassis ground, so indeed I don't get any groundloops on these

the bad part is that the drivers for these two cards are completely worthless...the Asus have a fixed sample rate that isn't automatically bitmatched whatsoever(KS/ASIO/WASAPI), and the Bravura runs the usual X-Fear drivers crapola..and on this card they've even removed the "audio creation" mode so no bitmatched playback whatsoever, and no ASIO/KS on XP

you can see here that even the foobar guys think that the Asus drivers are worthless: foobar2000: Change Log
Quote:

Added a workaround for horribly broken Asus Xonar drivers.

indeed the hiface looks money! but if the 0404PCI has a transf. and does bitmatched KS on XP...we might indeed have a deal

OTOH, my DAC runs a DAC9001 chip that does 50ps clock recovery

thing is, my computer is connected to an outlet that's not grounded...and I was getting noisy ground on both PCI and USB cards(that ran on their own wallwart), and you can see in the two links I posted above that another guy had the exact same problems over firewire cables...so why not coax groundlooping? but you're right, I'll try it! OTOH, optical will fix the issue for 100% sure.

I also run a grossly overclocked quad CPU..I've left the Spread Spectrum enabled, but still.

 

[ericj]

I seriously doubt that whether or not the connector used for coax is really 75-ohm or not makes any measurable difference for spdif.

Were i in the OP's shoes, I'd get a nice potted pulse transformer and an isolated RCA from mouser, desolder the exsting output on the sound card, glue down the transformer so it has it's legs in the air, and install the isolated jack on the existing bracket in place of the old jack.

 

[leeperry]

@ericj: apparently a glass optical cable is out of specs..and I don't really like the idea of being milked for an out of spec cable

I've just bought a 2m Audioquest VDM-XR top end coax cable for $20 shipped on ebay, it's their top end cable...it should be fine: AudioQuest VDM-XR

the OP card only does optical anyway..if I buy another CMI8768 card w/ coax, you're saying that I could install transfos myself?? and I would really get the same ground loop isolation as w/ optical?

@Magsy: do you run XP SP3? would you mind running a simple test to check whether KS/ASIO are automatically bitmatched on the 0404PCI please?

 

[ericj]

There's no reason you can't get coaxial from the board you've got now.

I've seen several boards where the signal from the codec just makes a Y and goes to both the optical header and the coax connector. Not all parts can drive both at the same time.

coaxial and optical carry the exact same signal, usually from the same leg of the spdif transmitter.

A look at the datasheets will tell you if you need to use an inverter as a driver for the coax port or not.

I don't remember saying anything about glass fiber cables. I don't see any reason they wouldn't work if properly terminated. 'course, i also don't see how, on lengths of less than a kilometer, they'd work any better.

 

[leeperry]

oh ok, well I got the datasheet for the DSP, I'll look into it!

so how would I go about adding transfos between the S/PDIF transmitter pins and the RCA plug? one on the ground, and we'd be in business?

well the Audioquest coax cable I've bought is 75Ω and high quality, so I'll go coax if any possible..need to find a 75Ω female RCA connector now, if it even exists

and I guess the wires I'd solder from the connector to the board would also pick up interferences(being within the computer case)..

 

[ericj]

A lot of people will tell you that 75-ohm RCA doesn't exist. I'm the guy saying it doesn't matter. Use a BNC if you must, but, I don't get the love for BNC here - every radio operator I know hates those things. The contact area is small, and fragile, and prone to oxidization.

There's a thread here somewhere about adding coaxial output to an m-audio transit. Good place to look for ideas on how to do this hack.

 

[leeperry]

hah..well, this guy did some nice modding on his 0404PCI: E-Mu 0404 mods

if KS is automatically bitmatched on XP, I might bite

OTOH, this board only has one 24.576MHz crystal, so 44.1 would most likely suffer..

 

[Magsy]

It usually changes from 44.1 to 48 and back but the other rates require the card to be set to a different profile. You can create shortcuts and it is not really any pain. It is a semi-pro interface so the software is nothing like Creative's usual fare.

I'm not really advocating the 0404, while there is nothing wrong with it I'd buy the Hi-Face if I were you.

epanorama.net/S/PDIF Interface

 

[leeperry]

do you run XP SP3? well I haven't found any other cheap soundcard running a transfo. on coax tbh...

could you run this simple test please?
-set the soundcard fixed sample to 48
-play a 48kHz in WMP over DS
-simultaneously, w/o closing WMP...open a 44.1kHz file in foobar over KS and ASIO.

a wild guess would be that KS will play, but ASIO will give you an error msg stating that it can't set the hardware sample rate

 

[ericj]

Quote:

Originally Posted by leeperry /img/forum/go_quote.gif OTOH, this board only has one 24.576MHz crystal, so 44.1 would most likely suffer..

Your assumptions here are total nonsense.

PLL clock synthesis has been the norm for 20+ years. They really can get 44.1khz spot on using a reference crystal that is not precisely divisible by 44.1khz.

'course, I think all clock upgraders (in sources younger than 20 years or so) are barking mad. And I won't be impressed until i start seeing crystals in ovens on these clock upgrades. Seriously, y'all talk like it's the bees knees, but nobody in that whole field seems to have paid any attention to what's been done about the problem of clock accuracy in, say, radio signal generation, where it actually matters rather a lot.

How do you account for thermal variance in your uber-clock? come on, how? If there's a chip of quartz in there anywhere at all, it's going to behave differently depending on temperature.

 

[leeperry]

well, all I can see is that Envy24 DSP and the M2Tech HiFace both carry 2 discrete clocks that are multiples of 48 and 44.1kHz...why would they have bother doing so if the Envy24 DSP could have gotten away w/ a single clock? it would have made their OEM customers happier.

also the CMI8788 only has one 24.576Mhz clock...its datasheet talks about a max jitter of 500ps.

first Asus released the Xonar STX using the CMI8788, then a few months later they added a CS2000 clock conditioner on top of its clock on the ST...and boasted on their website about much tighter jitter..I would even dare saying that the difference is VERY much audible between the 2 cards on headphones.

then some ppl swapped the clock for a killer 1ppm clock from Audio-GD, and said that stereo imaging went up through the roof!

anyway, I've found a CMI8738 board that has native coax...and it's dirt cheap, I like the sound of that...but I can't see a transfo. though

well, jitter is a recently discovered problem...as Burson says: http://www.bursonaudio.com/burson_clock.htm
Quote:

Jitter Error has only been identified as a deficiency in the last couple of years

 

[leeperry]

this would also be a good candidate for toslink AND coax: AUDIOTRAK MAYA 5.1 MK-II POS Sound Card 5.1-Channel - eBay

2 discrete clocks:

bit-perfect/automatically bitmatched KS/WASAPI, 24/96 S/PDIF(and it does support PCM24, not just 16/32), and it forbids SRC too

BTW, it's got a big cap right behind the S/PDIF output...could it be there for the galvanic isolation of coax(that goes through a break out cable)?