Topic: Correct Word Clock Connection

Hello to all RME members,

When I recently joined the forum I was kindly helped by members and administrators who answered my questions before I bought a FF 800. Thank you all for your help. It allowed me to buy a FF 800 and I am a very happy chappy indeed.

I understand these FF 800s have an awesome clock and so I want to get that clock signal to all my digital gear in the correct way using word clock.

I am saving for another FF 800 and that will give me four pieces of digital gear which I hope to connect with a word clock chain.

So my gear will be:

FF 800 master
FF 800 slave
Digidesign 003 rack  ( Avid told me that the WC input on the 003 rack is 75 ohm terminated)
Focusrite Octopre LE ( Focusrite publish that the Octopre LE Word Clock input is also 75 ohm terminated)

I have read the FF 800 instruction manual and I think I understand about 75 ohm termination.
It is the physical cabling of the above units that I would like assistance with please?

Can I propose four different situations to allow members to just reply with a number choice.

1)  DAISY CHAIN WITH NO  "T"  ADAPTORS
    WC out of the FF 800 master into the WC in of the FF 800 slave.
    WC out of the FF 800 slave into the WC in of the 003 rack
    WC out of the 003 rack into WC in of the Octopre
I see problems with this set up because of the 003 rack inside the WC chain. It is 75 ohm internally terminated so it may degrade the WC output signal. Avid told me that when the 003 rack is slaved to an external WC signal its WC output is regenerated. I imagine that when the 003 regenerates the sync signal at its WC output that it may not be in phase with the input???

2) DAISY CHAIN WITH T ADAPTORS
    WC out of the FF 800 master into the WC in of the FF 800 slave
    ( The FF 800 instruction manual suggests it is actually better to use the WC output of the FF 800 slave when it is inside a WC chain because the signal is perfectly regenerated at the WC output so my next connection does not use a T adaptor)
    WC out of the FF 800 slave into a T adaptor on the WC input of the 003 rack
    Connect the free wing of 003 WC input adaptor to the the WC input of the Octopre which is already 75 ohm terminated internally.

My concern with this method is that the T adpator at the WC input of the 003 rack is plugged into the 75 ohm termination of the 003 WC input. Maybe that extra resistance interacts badly in the WC chain.??

3) SPLITTING WC OUTPUTS
   WC output of the FF 800 master into the WC input of the FF 800 slave
   Connect a T adaptor to the WC output of the FF 800 slave
   Connect one wing of the FF 800 WC output adaptor into the WC input of the 003 rack
    and connect the other wing to the WC input of the Octopre.

This method will split the output of a WC signal and I dont know if that is electrically OK? However, it has the advantage of placing both the Octopre and the 003 rack at the end of the word clock chain. In this case the WC chain will have two ends and dont know if that is OK.

4) FF 800 SLAVE REGENERATION OF 003 WC
    WC output of the FF 800 master into a T adaptor plugged into the WC input of the 003 rack
    Free wing of the adaptor at the WC input of the 003 to the WC input of the FF 800 slave
    WC output of the FF 800 slave connected to the WC input of the Octopre ( hopefully the FF 800 slave will regenerate whatever bad things the 003 rack may have done to the sync signal.)
I think I like this method best but I am worried that the clock passing to that internal termination of the 003 rack.

You will notice that I am not thinking of using a WC distribution box like Apogees Big Ben because I have read too many reports that WC distribution amplifiers can create problems of their own and of course a daisy chain of WC is infinitely cheaper...
I look forward to hearing from you with your number choices or any advice you may have.
I feel like my FF 800 purchase has opened the door to a World of intelligent friends who love music as I do.

Kind Regards to all and thanks to Matthias and company for making such incredible gear,

Jim

Re: Correct Word Clock Connection

Hey there Jim,

I feel for you man. No-one answers your question and you even made it easy for us by giving us the number option for a reply but obviously no-one knows the answer. Why else would you be ignored.

I wish I knew the answer to your question becaue I now worry that my system is set up incorrectly.
I'm not even using WC at all... just the ADAT but I hear that it is better to use WC in larger systems but your post makes me realise I dont know how to set up a WC chain properly either.
Surely someone in the forum knows.
Maybe the RME crew will make a recommendation about how to set up a WC chain in the best way.

Good Luck man....hope you get the answer soon..for my sake too.
eLeV8

Re: Correct Word Clock Connection

Hey Jim,
I just did a google and saw an article from Dan Lavry saying that he is not a fan of word clock distribution amplifiers. He says the best method is to use a WC chain with the T bar appraoach.

Still dont know what order to plug everything in...
eLeV8

Re: Correct Word Clock Connection

There is no single answer.  Dan Lavry says use Tees for distribution - and I believe RME is on board with that (I tend to use that method myself).  SSL specifically states NEVER to use Tees and to ALWAYS use a DA with 1 isolated output per device.

So choose based on who you trust more - or what actually works with the least investment  (I like Tees myself assuming your gear is unterminated) cool

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