Word clock set-up for UAD Apollo 8 / Neve DPD / Focusrite Octopre

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Word clock set-up for UAD Apollo 8 / Neve DPD / Focusrite Octopre

Post by skipper01 »

Hi everyone, can you help me out?
I wish to extend the inputs available to me on my UAD Apollo 8 interface.
My wish is to use a Focusrite Sapphire Octopre via ADAT optical (not here yet) plus use the better convertors in the Neve 1073 DPD connected via Spdif IN on the Apollo to max out all connectivity.
I am concerned/confused a bit by possible issues with clocking/Word clock.
To date, the 1073 DPD seems to work fine literally with just a AES/EBU XLR OUT to phono 'bodge lead' to the Spdif input on the Apollo.
I did try out the BNC Word clock OUT on the Apollo to the Word clock IN on the 1073 DPD and implemented the in built 75ohm switch on the 1073.
The light on the front of the 1073 indicated sync via word clock. The sound seemed fine and solid before and I didnt hear any difference with the clocking connected.
I'm going to be adding a Focusrite Octopre very soon for the ADAT (via optical). Should i anticipate any issues if i just connect the Optical out on this to the optical in of the Apollo?
Is this where clocking might be an issue with numerous devices connected though?
If so, would the correct connectivity be ie Word clock OUT of the Apollo to Word clock IN of the Octopre via a BNC T connection to then also feed the Word clock in on the 1073 DPD that has the 75ohm built in termination?
Without sounding daft and pre-empting - what benefit will i get from a Word clock as (to my ears) it all sounds fine?
Many thanks in advance for any replies/help
skipper01
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Re: Word clock set-up for UAD Apollo 8 / Neve DPD / Focusrite Octopre

Post by Hugh Robjohns »

The rule is there can only be one clock master, and everything else has to be synchronised to that.

Often the options are dictated by the connectivity of the different devices -- some will have word clock inputs and some won't.

If you want to keep the apollo as the master and send word clock from that to the other two preamp/converters via a t-piece, that is fine. Just remember to configure both units to use the external clock, and make sure only the last device in the wordclock chain has a 75 ohm termination.

If digital inputs aren't synchronised you'll get clicks as samples are lost. Whether the clicks are audible depends on the nature of the signal.
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Hugh Robjohns
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Re: Word clock set-up for UAD Apollo 8 / Neve DPD / Focusrite Octopre

Post by skipper01 »

Ok, many thanks for this info Hugh.
I think the Apollo as the Master makes sense (with the sync set to internal within console software) to spit out it’s word clock as I’d rather only switch on the power to the neve 1073 DPD when required (rather than that being the master).
I’ll wire as described and as I first thought.
skipper01
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Posts: 183 Joined: Thu May 15, 2003 12:00 am Location: Bristol UK
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