What is S/PDIF?

petreestow · Post by **petreestow** » Sun Jan 25, 2009 9:00 pm

I have an ART Digital MPA Preamp that I'm trying to hook up to my firepod Via S/PDIF. I'm just wondering what S/PDIF is..is it like a digial out channel of it's own? thanks guys

JGriffin · Post by **JGriffin** » Sun Jan 25, 2009 9:33 pm

S/PDIF=Sony/Philips Digital InterFace--it's a digital stereo input/output, basically.

David Piper · Post by **David Piper** » Mon Jan 26, 2009 11:18 am

SPDIF is a two channel format that carries clock with it. The confusing thing is that sometimes it's carried by a TOSLINK optical cable (the thin ones, with the little red light poking out of the end. Usually you have to remove a little cap from your gear to access the part where it goes in), and can also be carried over metal coaxial cable that ends in a single RCA style connector (like the red & white connectors you see on the back of home stereo components, except there's only one instead of two). M-Audio makes a converter box to get between the two types of connections, if you have gear you need to connect with opposite connection types.

One thing to remember about SPDIF is that the device sending the signal (ART MPA) will be doing the A/D conversion instead of your interface, and your interface will likely get clock from it too. When I connect my API A2D to my Digi 002 via SPDIF, it does all my clocking, and converts anything coming from the API pres, which is awesome. When I also need to use my DigiMax FS to get extra inputs, the Digi 002 can't have two clock sources, so the Digimax does all the clocking - which is decidedly less awesome. I'd think it's a toss-up between the ART unit and your interface providing clock, so it's no big deal for now. But worth thinking about if you add more digital gear later.

petreestow · Post by **petreestow** » Mon Jan 26, 2009 4:55 pm

thanks for your help guys. just one more question, say i'm recording vocals on both channels and i want to send them to my firepod, could i use the s/pdif to do so? would it act the same as if i were using xlr cables? is the quality better then xlr? sorry..i'm just not very clear about this yet!

inverseroom · Post by **inverseroom** » Mon Jan 26, 2009 5:01 pm

dwlb wrote:S/PDIF=Sony/Philips Digital InterFace--it's a digital stereo input/output, basically.

And here I thought it was Some Perverse Dipshit's Impulsive Folly.

farview · Post by **farview** » Mon Jan 26, 2009 6:54 pm

petreestow wrote:thanks for your help guys. just one more question, say i'm recording vocals on both channels and i want to send them to my firepod, could i use the s/pdif to do so? would it act the same as if i were using xlr cables? is the quality better then xlr? sorry..i'm just not very clear about this yet!

Spdif is digital, the XLR is analog. The only difference it could possibly make would be if the converter in your preamp is a lot better than the one in the firepod. It isn't, so it won't really make any difference which you use.

Also, depending on how the firepod works, you might be able to record 8 channels using the analog inputs AND another two using the spdif, for a total of 10 channels at once.

Mane1234 · Post by **Mane1234** » Mon Jan 26, 2009 7:23 pm

So with the Digi which has both S/PDIF and Lightpipe is there any difference between the two or are they basically the same thing and just two different methods of delivering the signal? My CD burner has both as well so I was wondering if one might be a better way to send the 2 mix by for mixdown.

farview · Post by **farview** » Mon Jan 26, 2009 7:32 pm

Spdif is two channels of digital I/O

Lightpipe is 8 channels of digital I/O

David Piper · Post by **David Piper** » Mon Jan 26, 2009 8:33 pm

S/PDIF isn't better or worse than XLR, or any other type of cable or connection. It is a method of getting audio from one piece of equipment to another. There are LOTS of things that will affect the quality of your audio before it hits the SPDIF cable, namely the source, the mic, the mic pre, and the A/D converters. Don't sweat the quality of the SPDIF connection too much.

Mane1234 · Post by **Mane1234** » Mon Jan 26, 2009 8:50 pm

I thought Lightpipe was just any cable that had the red light in it. I didn't know it was specifically 8 channels...Thanks for the info.

alex matson · Post by **alex matson** » Tue Jan 27, 2009 10:39 am

It's the last sound a pubic hair hears.

dsw · Post by **dsw** » Tue Jan 27, 2009 1:25 pm

Lightpipe was invented by Alesis for their ADAT machines, but they shared the technology and lots of companies use it now.
8 channels max out at sampling rate of 48k unless you have a device (sadly Digi doesn't allow this) that can use a protocol SMUX which gives you 4 channels of 96k.

I love the sound of that word : SMUX
fun to say

*repeats the word SMUX out loud a few times just for fun*

Justin Foley · Post by **Justin Foley** » Tue Jan 27, 2009 5:32 pm

alex matson wrote:It's the last sound a pubic hair hears.

If there's some kind of weekly award that people pass out around here, I nominate this post.

= Justin

Andy Peters · Post by **Andy Peters** » Wed Jan 28, 2009 11:29 am

Mane1234 wrote:I thought Lightpipe was just any cable that had the red light in it. I didn't know it was specifically 8 channels...Thanks for the info.

If the hardware is designed to allow it, the lightpipe interface can also carry 2-channel S/PDIF data.

The lightpipe transmitter and receiver devices are standard items. The format of the data they carry is determined by whatever feeds data to them.

-a

Jay Reynolds · Post by **Jay Reynolds** » Wed Jan 28, 2009 11:35 am

More importantly, how is it pronounced:
1. Speed-if
2. Spid-if

I'm a fan of #2. #1 sounds kinda gross to me.

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