lightpipe sync question

[bit]

I've just bought a RME HDSP9652 card, and the lightpipe thing is a
little new to me. Is the sync reference going both ways in the
pipe? I'm gonna have one AlesisAI3 AD/DA (8 outs and ins) and one
FOSTEX ADAT AD box (8 inputs and lightpipe out) and an old ADAT
player for monitoring the FOSTEX inputs. They were sold out for
AI3's. This is just a temporary solution while I'm doing a
recording next weekend. I don't wanna go down the road with
internal Totalmix routing for monitoring or using Saw-Live mode for
it just yet. It's too new to me and are not gonna take my attention
away from the music on this project. Well the bottom line of my
question is this: Does the Fostex have to be master while it's not
having a lightpipe input?

Cincerely
Bjorn

[Yura]

: Does the Fostex have to be master while it's not
having a lightpipe input?

Cincerely
Bjorn

No, it doesn't. And others don't too

[ghowardjr]

If I understand your question correctly, then the answer is as follows:

Light pipe clock is not carried bi-directionally. It only comes from the sending unit. If there is not a word clock input on the Fostex and/or a light-pipe input that it can clock to, it MUST be the master. The AI-3 has both adat ins and outs so that's not a problem. You will make the RME card slave to the ADAT input from the Fostex.

Hope this helps,
Gary

[Bob L]

I would plug light pipes to each converter on the ins and outs and use the RME as master... that way the RME card always follows the rate from SAWStudio.

Each converter box should be set to slave from the optical.

Simple and guarenteed to work. Spend the money on the extra light pipes and always connect both in and out to the converters.

Bob L

[bit]

Thanks for the quick replies.

Ok, I think I got a little wiser here. The Fostex device that I'm getting monday is called AC2496. It only has lightpipe out,no in (only analogue), but it does have word-clock it seems. I bought it second hand today and the only reference I have is a pretty blury picture on this site: http://www.fostexinternational.com/docs/products/ac2496.shtml
Bob, is it really a big deal if the RME ain't the master. In my experience, using word clock is not the best way to go. The only experience I have with this is syncing two Laylas, and they really drifted using word or super clock. Spdif OTOH was steady as a rock. Besides I need a very long cable for that.

Cincerely
Bjorn

[Bob L]

As long as you get one stable clock source and everything follows... great... but if the RME is not the master and you open a project at 48k following a project at 44.1k you are subject to accidently not notice that you are playing things at the wrong speed... you will have to manually adjust your clock source to match the session rate... sounds simple enough, but I have seen many people mess up projects from that one simple mistake that slips through the cracks during the heat of sessions.

If you record and stamp files at one rate while the clock source is at another rate... it gets very tough to fix the mistake later down the road when you discover it. :)

So stay at one rate or be very aware at the start of each session to align the session rate and clock rate manually.

Bob L

[bit]

Thanks a lot Bob. You are fast.

Bjorn

[ghowardjr]

Here's a better picture. Looks like you only have 2 choices, make the fostex unit the master or slave it to the word clock from the RME (as master) and slave the AI-3 with two lightpipe cables.

Best of luck,
Gary

http://www.fostexinternational.com/images/product_img/press/AC2496_Slant_Wide.jpg