High quality nonos PC based DAC

[peufeu]

Yes, this soundcard is very good. It has no bells and whistles (not even a mixer volume control), but it works beautifully and is perfectly adapted to my purpose.

And, with the 8 outputs, I'll implement a digital crossover soon.

Now, the format.

I had this CD723 and made my DAC to work with it. I put the master clock in the DAC and fed it to the CD player (adequate buffer, transformer, coax), then fed the SPDIF from the CDP to my DAC. This is synchronous reclocking.

However I discovered that CD723 was not bit-accurate -- ie it's unusable for hi-fi. And I wanted to use this soundcard... what to do ?

Simple man, plug the CD723's spdif out into the computer, and everything is synchronized !

DAC feeds its clock to the CDP
CDP feeds its SPDIF to the computer
Computer feeds its SPDIF to the DAC.
All is synchronous.

Normally I would have used a SPDIF encoder (CS8412's twin, I don't know the reference) fed with the DAC clock and null data to build a bogus SPDIF signal and sync the computer on it. But when I realized the CD723 would do this job, and I didn't need to solder anything, laziness took over.

For your application, I'd advise to use a SPDIF encoder (the reverse of CS8412) fed with all-zero data and clocked with the master clock in the DAC. Use a multiple of Fs of course.
This will give you a bogus SPDIF signal which will contain the clock and no data. Sync the computer on that and you're done.

And it doesn't involve butchering the soundcard.

You can transformer-couple everything to isolate the PC from the DAC (strongly advised).

[Nielsio]

Nice work, people.

I've also done somewhat the same:
http://www.diyaudio.com/forums/showt...572#post272572

However, I've also included a digital equalizer between computer digital out and DAC (both spdif).

If you like open-source / free / good stuff, then go for Ogg vorbis instead of WMA.

[peufeu]

Why use a Behringer when you can do the same with the PC for free ?

[fedde]

Interesting thread! I have been thinking about these things for the past months too! I was still looking for a solution to make the PC a slave for clocking. This S/P-DIF based synchronisation is a nice idea! I hope that the CS chips are still available for that!

Fedde

[Nielsio]

Originally posted by peufeu
Why use a Behringer when you can do the same with the PC for free ?

Well, it's not that easy with the PC (on the contrary). Also time-delay is an issue if you want to do it right.

[peufeu]

Ah, yes, a PC will always have a higher latency than a DSP box. That's a very big problem for home cinema (any delay between image and speech is problematic), but not for music.

As for interesting active crossover software, try BruteFIR. But you have to design your own impulse-responses, which is a bit messy if you are not into signal processing...

[peufeu]

Ah, yes, I forgot :

Use that SPDIF soundcard to rip unrippable CDs, too..

[fedde]

Originally posted by peufeu
Ah, yes, a PC will always have a higher latency than a DSP box. That's a very big problem for home cinema (any delay between image and speech is problematic), but not for music.

Well it is... for example when you use software samplers like Gigastudio. BTW: the support of GSIF is included on the RME cards, that's a plus!

The latency of EQ on a PC will likely be lower than on an external EQ. An external EQ will need to buffer data (another time) in order to filter it.

In the end, the PC will be a more flexible solution for EQ (and the clocking problem is solved easier without extra external equipment).

Fedde

[peufeu]

OK, what I wanted to say is :

Latency is not a problem when playing pre-recorded music.

All other cases (especially live musicians)... latency is a problem.

On RME cards, you can buy an extra "wordclock input" module, so you wouldn't even need to use a SPDIF encoder to sync your card... elegant.

[fedde]

Originally posted by peufeu
On RME cards, you can buy an extra "wordclock input" module, so you wouldn't even need to use a SPDIF encoder to sync your card... elegant.

I saw that feature on the page, and I already wondered if I could use it for that. Thanx for the information! The hammer series is also interesting, but that's is more expensive. Anyway, I need Midi...

Fedde