by Y-my-R » Wed May 02, 2018 7:28 pm
First of all, of course Phil is right... if you use a master clock that has multiple bnc word clock outputs, then you don't have to worry about modifying the apogee clock card, etc., and you can just connect a word clock output from the master clock, to each device that should receive the clock signal and slave to it.
It's still possible to clock everything together without a master clock... but yes - in case of a dual d8b setup, this means that one of the apogee clock cards needs to be modified, to allow daisy chaining.
I think the reason why there's a Word Clock BNC out on the Apogee card, is when you want to use the d8b as MASTER, and clock other devices off of it. Not if you want to use that same d8b as slave, and basically pass the clock signal it receives, through to the WC out. In other words, the OUT doesn't work as a THRU. Only as an OUT when the d8b runs as MASTER.
That's at least my assumption (and sorry about the capital letters... I'm not yelling, just trying to emphasize important points).
I also think it's not thought through very well, to allow to cascade two d8b's, but don't include the necessary features (non-termindated WC input port), without using a Master Clock. Maybe the assumption on Mackie's and Apogee's side was, that if you use two $10,000 consoles, you should be able to afford a Master Clock to go with them, not sure.
A much simpler option would have been, to just NOT terminate the BNC WC ins on the Apogee cards at all. Then you can just use a regular BNC Terminator at the end of a chain, and no Terminator at Daisy Chained devices. But that's kind of always tricky, since every manufacturer does it however they want. Some terminate, some don't. Some make it switchable, others don't. It's always some degree of reading manuals to find out how the BNC connectors work, and then some trial and error.
To answer your question in your first response, though - yes, one Apogee card should be terminated, the other one should be modded to allow to turn the termination off.
My example worked a little different, but in your case, the word clock setup w/o a Master Clock would look something like this:
What you need:
2 BNC cables
1 BNC T-connector (connect to WC in on "modded" d8b)
Motu 2408: Set to Generate Word Clock (Master).
->BNC Out on 2408 connected to T-connector on BNC In on d8b w/modded Apogee clock card. Termination set to off, configure d8b to sync to External.
->On the same d8b, on the open end of the T-connector on the WC In, continue the daisy chain to the second d8b, and connect the end of the cable to the BNC In. Set that d8b to sync to external word clock as well.
In short:
2408: Word Clock Master (via BNC out)
First d8b: Word Clock Slave (via BNC In on T-connector, termination off, cable continues to next d8b)
Second d8b: Word Clock Slave (via BNC In that comes from the other d8b's T-connector, and goes into the WC in at the second d8b).
Since the second d8b terminates, as it uses the unmodded card, that end of the WC chain should be good. As for the 2408 - I "guess" that this one internally terminates as well, but if you find out that it isn't, then you'd have to get another T-connector and a BNC terminator, and connect that to the BNC Out on the 2408. (One side of the T being the terminator, the other going to the first (modded) d8b WC in).
I know this sounds complicated, but it isn't really that bad when actually doing this.
I hope this helps!