S/PDIF confusion and questions :)

[fgimian]

Hello folks, just signed up to these forums

I just bought a TI Desktop last week and have been getting quite confused with the way S/PDIF and its clock works. I really really would appreciate anyone's help on this one. I've also posted this on Gearslutz but I realised after posting that this place would be a lot more suitable

So as mentioned, I have a Virus Ti Desktop (love this thing!!) and am connecting one set of outputs and one set of inputs for no-latency monitoring and processing audio through the Virus respectively.

So here is my configuration:

Access Virus USB -> PC USB input
Access Virus TI S/PDIF out -> Echo Layla3G S/PDIF in
Echo Layla3G S/PDIF out -> Access Virus TI S/PDIF in

I have disabled the feedback loop and S/PDIF lights up in my Layla3G console as a possible clock source.

So at this point, I really should have 2 options (please correct me if I'm wrong)...
1) Use the Layla3G clock (Internal) and set the Virus TI to expect a clock signal on its S/PDIF in.
2) Use the Virus TI's clock (S/PDIF)

So I attempted 1) but got heavy crackles and pops after about 1 minute of usage. 2) on the other hand worked 100% perfectly. Of course, the biggest issue with 2) is that everytime I turn off my Virus, I must switch back to the Internal clock and vice versa, which is really annoying.

I read on a few posts that when using USB, S/PDIF can not sync from a soundcard because the USB interface has its own sync. Does anyone know anything about that?

Just to confuse matters furthur, if I set my Audio Clock to Internal on the TI and set the Clock Source to Internal on the Layla3G console, it works perfectly! But this just doesn't make sense since they would now be using independent clocks and thus should be off sync, shouldn't they?

Anyway, I then started wondering why 1) wasn't working. In theory, it really should, Layla's S/PDIF out should be sending a clock signal to the Virus TI's S/PDIF in and the TI should sync from it.

So I thought, ok, let's take the Virus TI out of the equation and confirm that the Layla is actually generating a usable S/PDIF clock signal. Thus I plugged in the following:

Echo Layla3G S/PDIF out -> Echo Layla3G S/PDIF in

I disabled the feedback loop and once again, saw S/PDIF light up in my Layla3G console as a possible clock source.

At this point, I still had my clock source set to Internal, here's a screenshot:



Ok, all looking good and music was playing back ok at this point. So now, I figured I'd switch the clock source to S/PDIF to confirm the clock was being generated correctly, here's a screenshot of what happened when I switched the clock source to S/PDIF:



Now this freaked me out for 2 reasons....

1) What on earth is the signal on Analog in 7&8? There is nothing plugged into it! Listening to this signal, I had something pretty similar to white nouse.
2) When I played back a tune, the sample rate was insanely fast, regardless of whether I had my sample rate locked in the console

So at this point, I was going a little bonkers and decided that I needed help.

I have written to Access Music and this is the response I got:

if you don't send audio clock to the Virus TI via SPDIF (so establish also a SPDIF connection to the TI), then it is normal that you're getting sync issues, that's why it only works with the TI being the clock master on your system if you don't connect the SPDIF Out of the Layla card with the TIs SPDIF In.

I made it clear that I had the signal coming into S/PDIF in of my TI and the guy responded but added nothing additional to this comment above.

I wrote to Echo Audio and got this:

- No, are you using a shielded 75 Ohms RCA cable ( video quality)?
- Make sure your Layla3G Echo console is set to SPDIF clock ( SPDIF in)

I don't fully understand why I should have to use the S/PDIF clock though, according to everything I've read, this should work with Echo's internal clock.

I since sent them another mail about the wierdness shown in the screenshots above, but haven't heard back yet.

If anyone can help me at all, I truly would appreciate it. I really think I must be missing something, or going a little nuts

Thanks so much for reading
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[mitchiemasha]

complications.

must be your sound card if nothing is connected to it. the feedback loop you have created even though you have disabled it must create some kind of conflict to audio in 7&8. could be a software bug that they havent come accros yet.

plus setting it to clock source spdif in when its receiving spdif from itself means that it isnt transmiting the clock source at its own spdif out put. now there is no clock source at all. I realy need a better way to explain what I jst said. to be honest am jst guesing.

what virus said abt the spdif I would of expected.

[fgimian]

Originally Posted by mitchiemasha

complications.

must be your sound card if nothing is connected to it. the feedback loop you have created even though you have disabled it must create some kind of conflict to audio in 7&8. could be a software bug that they havent come accros yet.

plus setting it to clock source spdif in when its receiving spdif from itself means that it isnt transmiting the clock source at its own spdif out put. now there is no clock source at all. I realy need a better way to explain what I jst said. to be honest am jst guesing.

what virus said abt the spdif I would of expected.

Thanks for all your help, essentially that feedback loop is not such a concern I guess, as long as I can get the Virus TI in sync and working with the Layla3G's internal clock (so I don't have to constantly re-adjust settings). After many more tests with changing clock settings:

1) Layla3G (Internal) / Access Virus TI (Auto) + USB plugged in: Causes pops and clicks
2) Layla3G (Internal) / Access Virus TI (Auto) + USB NOT plugged in: Works
3) Layla3G (S/PDIF) / Access Virus TI (Auto) + USB plugged in: Works
4) Layla3G (Internal) / Access Virus TI (Internal) + USB plugged in: Works

So right now I'm going with option 4) since it means I never have to change settings when I turn my Virus on or off. I'm not REALLY sure WHY it works though, in theory it shouldn't work since the they are each using their own clocks.

Also when looking at 1) and 2), I think this problem has something to do with sync being sent over USB. I have no idea how this works and the manual is very brief on it too

From the manual (page 159):

Audio Clock
Source
Specifies the source of audio clock used for synchronization.
> Auto: The default setting. Audio clock via USB or S/PDIF is automatically recognized, otherwise the internal one is used.
> Internal: Only use the internally generated audio clock.

If you can explain any of this behavior, it would be so so helpful to me

Thanks so much
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