SPDIF or, in this case, SPDIV

[mutilatedlip]

I've never really read up on the subject, but being as a few of my devices have digital outputs (MPC/Virus etc.) and I have a couple of SPDIF inputs on my soundcards, I'm now considering starting to use them.

However, I'm fully ignorant in this deparment of sync'ing issues etc.

I've always recorded in 24/48, so would I need to sync anything, or do anything apart from ensuring that they were all switched to the same sample rate?

I apologise for my stupid questioning.

Give me a MIDI lead and I'll be fine. Give me a SPDIF lead, and I'm looking down the end of it for the little laser.

[saxman]

I expected it would be difficult to connect my E-MU 1212M to my Roland VS-880EX via SPDIF. It was surprisingly easy.
The main thing to remember is that there is a master clock source. This is the master digital clock and it either comes from your soundcard or the device you are connecting to. On your soundcard you should have an option to set the master clock to either an internal source ( usually 44.1Khz or 48Khz ) or an external source.
To record from my 1212M to my Roland with an optical cable I plug a cable in to the optical-out on the 1212M and the other end in to the optical-in on the Roland. Then, on the Roland I change the Digital Clock Source to be "external" and the 1212M to have clock source as "internal" - this causes the Roland to lock itself in to the master clock source coming from the 1212M.
To record from the Roland to the 1212M it is a similar process but of course I plug in to the optical-out on the Roland and the optical-in on the 1212M.

So, just look for the master clock settings on your soundcard and other devices. You want only one device to be the master - set one to have an internal clock and the other to sync to an external clock and your devices should be locked together and talking to each other. One thing to remember is that SPDIF connections "want" to lock on to each other - all you have to do is decide which is master. Simple, I hope

[sureno]

yes i too am a Div when it comes to this, never used them and to be honest avoided doing so simply because i thought they would be complicated in syncing etc. well thanks saxman i now know otherwise

[mutilatedlip]

Me too - always avoided it. So basically, it's the same principle as MIDI.

What intrigues me is the fact that it's two channels of audio down a single cable. What is this devilry?

I guess it'll just appear as two channels in my DAW?

Thank you, by the way.

[sureno]

Originally Posted by mutilatedlip

Me too - always avoided it. So basically, it's the same principle as MIDI.

What intrigues me is the fact that it's two channels of audio down a single cable. What is this devilry?

I guess it'll just appear as two channels in my DAW?

Thank you, by the way.

i think it can be 8 channels even? im not sure though or am i getting that confused with ADAT?

[mutilatedlip]

That's ADAT. I'm fly with the ADAT

The next step would be selecting the highest quality clock source, as it's contained in the signal, am I right?

So would it be the clock source from the Virus Ti, Emu, or Mackie?

What am I looking for?

[sureno]

Originally Posted by mutilatedlip

That's ADAT. I'm fly with the ADAT

The next step would be selecting the highest quality clock source, as it's contained in the signal, am I right?

So would it be the clock source from the Virus Ti, Emu, or Mackie?

What am I looking for?

i hate all this side of things but got to learn it at some point

[mutilatedlip]

I agree. Technology is great, but it must've been amazing just starting the old 16 tracks back in the day and recording the sweet spots.

All this fannying around with cabling etc. Dear God!

[saxman]

Originally Posted by mutilatedlip

What intrigues me is the fact that it's two channels of audio down a single cable. What is this devilry?

Well, in the analogue world you'd be used to seeing your phono plugs and jack plugs etc and you'd be used to seeing one cable per channel. That's because trying to have more than one signal go down the one analogue cable would just not be too pretty - you'd have to have circuitry to mix them together at one end and split them apart at the other end - hoping your channels come out nice and clean after all that.

In the digital world the signal is completely different. Your analogue music signal HAS to go through a converter to convert it in to a digital signal and it therefore becomes a whole load of 1s and 0s 010100000101010101111010101
Now, with your two ends of the SPDIF locked together they get in to a nice little digital conversation with each other. For example "Hi! I'm SPDIF on the soundcard and I'm running a clock at 44.1Khz - anyone want to lock togetherwith me?" "Hi, I'm an SPDIF on an MPC and I've picked up you 44.1Khz clock and locked on to it" "Hi, MPC SPDIF, nice to meet you, thanks for locking on" "Here goes soundcard SPDIF, I've got some stereo music to send you. here's a little bit of left channel, here's a little bit of right channel,
here's a little bit of left channel, here's a little bit of right channel, here's a little bit of left channel, here's a little bit of right channel, etc, etc" "thanks MPC SPDIF - I've got a lot of decoding to do to get those little bits of digital info back in to stereo music, but hey, I'm really good at it coz I'm a professional soundcard."

Of course that is just my imagined summary of what goes on but it is kind of like that. As far as what it looks like in the digital world, well, it is just a whole shed load of 1s and 0s on and and on and on.

Not just 2 stereo signals get sent down one cable in that way - surround sound 5.1 and 7.1 can be sent in the same way. What can not be done though is surround sound in the new high definition and lossless formats for BluRay and HD DVDs - that is where the one cable devilry just runs out of time for switching between the channels to send so much data.

[mutilatedlip]

Oh man, I was freaked out by my perceived devilry of the stereo signal in one cable.

Now you confirm that they actually talk to each other in weird little voices and call each other by name, I'm officially freaked out.

[FrankGIK]

My studio is run on an ADAT backbone, but I send a 2-buss mix via S/PDIF to my MasterLink. In my case you have to decide how you want to clock everything...I could clock via ADAT, wordclock or S/PDIF. My systems clocks best from ADAT, but I can still send any signal to any of the outputs simultaneously.

This is NOT the case with many interfaces. In many cases, if you're clocking via S/PDIF, that is the only active set of outputs available...the interface can't keep active S/PDIF and firewire I/O's open at the same time. Check your manual to be sure.

Frank

[ecc83]

Come on chaps, two audio channel down one lead the work of Old Nick!

Have you never seen a DIN audio cable? And how many very high bandwidth channel do you get down a single UHF tv lead?

I did some tests a couple of years ago with S/PDIF. It is pretty rugged stuff if you remember it is rather low frequency RF and you cannot take the same liberties with it as I did with UHF. All connections must be soldered or very well crimped.

I ran the output of a minidisc recorder thru' a opt' to coax converter*via 2mtrs of audio RCA to 30mtrs! of TV lowloss on a drum (worse case) out via another audio grade RCA lead into a Trust S/C S/PDIF input. No trouble at all.

I then inserted a 75Ohm 12db attenuator in the line, still glorious sound!

I have my two desktop pc's looped via coax and can thus shunt realtime signals to and fro ( of course I CAN just copy the file over since they are netted but the loop was done first an we has gotten used.)

Lastly can I make yet ANOTHER plea for some enterprising firm to produce a HQ analogue line in to S/PDIF conveter? Just two TRS's in and coax out would do!

*Wine into water to make but at £15 a pop at Maps', not worth the trouble.

Dave.

[FrankGIK]

Dave, I'm a pretty well-traveled American, fairly heavily non-Westernized. You're the only Brit I know who still loses me in the British-isms.

What does, "the work of Old Nick" mean?

Frank

[TrevCircleStudios]

Dave, I'm a pretty well-traveled American, fairly heavily non-Westernized. You're the only Brit I know who still loses me in the British-isms.

Don't worry Frank. He loses us too! (I think the reference to old nick could be to the devil himself but who knows...)

[ecc83]

"Old Nick" is indeed an EPITHET for the devil.

Now I looked up "epithet" on wiki.....nope, don't understand it!

BTW, the OP that thought 2 signals down one wire showed diabolical intervention might be scared WITLESS to learn that stereo FM radio can carry THREE distict signals on ONE radio wave!

In fact stereo radio is only a further application of the MS mic principle, a technique you must be familiar with Trev' And stop siding with the colonials! However Anglophile they might be!

Dave.