Are all S/PDIF interfaces equal?

[DwaneHollands]

I'm Learning more about AD/DA convertors etc.

So from what I understand, on most audio interfaces such as 003R, MBOX2 and other brands they have S/PDIF ins and outs. They are digital outs, correct?

Which means the external device must be a convertor of some sort. Such as Black Lions Sparrow ADC. Meaning the conversion happens in the Sparrow ADC not my MBOX2. (obviously I would go from the Sparrow ADC into my S/PDIF INS. Since there is currently no Sparrow DAC)

Since it is a digital signal being sent and received by the S/PDIF ins and outs, does that mean all S/PDIF inputs and outputs are equal performance across brands? Since it doesn't rely on any conversion. The conversion happens 'out of the box' so to speak?

Also, from what I understand the DAW' can sync it's clock source through the S/PDIF channels with the external device's clock. Is that the only way to sync clocks with s/pdif?

I realise this is kind of a disjointed post. ultimately is there any difference between vendor's A's S/PDIF implementation on their soundcard/audio interface versus Vendor B's? And are the results strictly dependent on the Convertor and Clock in the 'external device' - such as the Sparrow ADC?

Thanks for Humouring me!

[wez]

oh no, i can feel a conversation on jitter about to happen.... please no, not again.

(ahem... search for jitter, clock, etc and enjoy)

[chris p]

Dwane

The BL Sparrow looks a nice little unit, doesn't it.

In principle, a digital signal has no degredation because the pulse is either there for a 1 or not for a 0, yes? In the real world, the cable can have "echoes" of the digital pulses that can turn what should be a 0 into a 1 at the receiving end, and the receiving unit needs to know EXACTLY when to look at the wire to see if its a 1 or a 0 (this is the whole issue of clocking, PLLs and jitter).

Assuming adequate quality cabling and synced clocking, these are very minor issues compared to the quality of the AD or DA conversion and the quality of the analog and digital circuitry in the boxes at both ends. In other words, SPDIF is just a protocol for getting 1s and 0s from one box to another - the real question for audio quality is what those boxes do with the digital bits once they have them. As an example, digital clocks are electrically noisy things, and having a digital clock sitting next to a mic level signal or transformer is probably not the greatest thing to do. So yes, all SPDIF is essentially the same, and thats why you can connect the devices together - but not everything with an spdif input and output will sound as good as each other.

[DwaneHollands]

ThAnks wez and chris! That's what I needed to know. Yeah wez did do some searching around. Read some stuff off lavry engineering site. Shapng the noise....choosing how to shape the noise...uggghhh thAt's getting heavy!

[excuse iPhone formatting]

[lumbago]

I have a few here - Echo Mia PCI card, Roland M1000 mixer, Roland MMP2 mic pre, Lexicon MPX500 and Focusrite Trakmaster with the digital I/O card.

Yes - junk, I know. At least I'm deaf so I don't notice. There is a barely perceptible difference between the units. In the grand scheme of things I tend to run a word clock over them - usually from the M1000 out to the other devices. Getting the word clock adjusted for daylight savings .... now there's the rub.