ADAT at 96 kHz

[Eralde]

Hi!

I have a MOTU 8pre interface and looking for something to extend it to full 16x12 mode. I found Focusrite OctoPre mk2 Dynamic device which has 2 input ADAT connectors and 2 ADAT's for output - same as 8pre. But in the device's manual the wordclock sync is used when all 4 of them are working (24/96 mode). Since 8pre does not have a wordclock connector, I can't use 8pre + octopre as manual suggests me to.

There are 2 questions about such setup:

1. Will clock sync via ADAT only without wordclock in 24/96 mode?
(to my knowledge the answer is NO, which is very sad situation...)
2. Which device is preferable to be the master?
(I've heard that 8pre's clock generator is far from the best.)

Thanks in advance!

[mhschmieder]

I have the OctoPre mk II without dynamics and without ADAT in (just ADAT out), so am trying to "mix in" your information to create the big picture.

In S/MUX Mode, channels 1-4 go through one ADAT at 88.2 or 96 kHz, and channels 5-8 go through the other. On the OctoPre mk II, I can set either it or the RME Fireface 800 as the master clock, but if the OctoPre mk II is not the master clock, it needs to receive Word Clock via BNC cable.

I don't think in this case that duplex mode affects the possibilities of word clocking.

Going the other direction, given your Dynamics version of the OctoPre mk II and its ability to receive ADAT from your interface (in this case, MOTU vs. RME), have you checked whether the OctoPre mk II Dynamics can receive word clock via ADAT if there is no data being sent from the MOTU unit? Is it possible to route a mix loop-back via the ADAT from the MOTU such that it sends clock signal?

I don't know which of the two units has the better word clock, but often at the consumer level it's the newer device, when there's a three to four year gap, as the differences between vendors don't usually transcend the general onward march of progress across the industry.

[Eralde]

Thanks for the fast answer!

In S/MUX Mode, channels 1-4 go through one ADAT at 88.2 or 96 kHz, and channels 5-8 go through the other. On the OctoPre mk II, I can set either it or the RME Fireface 800 as the master clock, but if the OctoPre mk II is not the master clock, it needs to receive Word Clock via BNC cable.

I don't think in this case that duplex mode affects the possibilities of word clocking.

I haven't already bought an OktoPre device, just considering it as an expansion. But from your experience I got that my scheme should work with OctoPre as master & 8pre as a slave.

Going the other direction, given your Dynamics version of the OctoPre mk II and its ability to receive ADAT from your interface (in this case, MOTU vs. RME), have you checked whether the OctoPre mk II Dynamics can receive word clock via ADAT if there is no data being sent from the MOTU unit? Is it possible to route a mix loop-back via the ADAT from the MOTU such that it sends clock signal?

The point of using ADAT inputs on OctoPre is to get more outputs, because 8pre only has master/headphones. But, yes, mk2 Dynamic have "ADAT clock source" option - the one which not Dynamic revision of the device does not have (according to manual), so I think that this will work.

My question was caused by a thought that S/MUX technology leaves no place for clock sync. I couldn't find a straight answer on whether S/MUX over optical ADAT sends sync or not. But now I know that it is.

I don't know which of the two units has the better word clock, but often at the consumer level it's the newer device, when there's a three to four year gap, as the differences between vendors don't usually transcend the general onward march of progress across the industry.

To my knowledge both devices have no big difference in age (I have no info about previous revisions of 8pre, but I suppose there were some, mine is latest, bought it 2 months ago).

Thank you very much for your answer

[1nput0utput]

1. Will clock sync via ADAT only without wordclock in 24/96 mode?
(to my knowledge the answer is NO, which is very sad situation...)
Yes, an 88.2 kHz or 96 kHz ADAT stream carries a clock signal just like a 44.1 kHz or 48 kHz stream.

2. Which device is preferable to be the master?
(I've heard that 8pre's clock generator is far from the best.)

It probably doesn't matter. But if you want to see whether it makes an audible difference, test it both ways. I would expect that there will be no noticeable difference as long as the two devices are configured properly.

[mandobilly64]

I have the older Octopre and an 828 Mk3 and use the Octopre as the master via Adat. I have actually gone back to recording at 24/48 because of the DSP drain on the Cuemix FX eq/compression is way less than recording at 24/96, but I was using it this way before at that rate and still do when recording LP's.

Peace,
Billy