BNC distributor box?

Discussion in 'Location Recording' started by Exsultavit, Apr 22, 2006.

  1. Exsultavit

    Exsultavit Active Member


    I'm currently using my workhorse Apogee PSX-100 as a master clock for my Alesis HD24- using the BNC clock out of the Apogee and feeding the 'word' in on the HD, effectively removing the HD24s internal clock and replacing it with the Apogee's.

    In an upcoming project, I'll be using two HD24s- NOT as a 48 track 'synced' unit, but as seperate machines- with one running as a safety. I'd like both units to clock to the Apogee, though.

    The thing is this: The Apogee only has one BNC 'word' output. Is there a splitter of some kind that will allow me to use the single BNC out of the Apogee as master for both units?

  2. ptr

    ptr Active Member

    Sonifex in the UK has just such a box. Havent used this wordclock splitter tho, but I have several of their XLR splitters.. An they're quite sturdy!

    I'm sure that there are other makes as well..

  3. DavidSpearritt

    DavidSpearritt Well-Known Member

    We used to use just plain old BNC T pieces. It worked at the tiime, is it not recommended practice now?
  4. Zilla

    Zilla Active Member

    W/C output circuits are designed to transmit their signal into a 75ohm impedance. This means that both the cable and the termination in the receiving device's input should be 75 ohms.

    If you take your apogee's w/c out and strap it across two w/c inputs, the parallel impedance will be only 37.5ohms. This may cause interfering reflections or sag in the square wave clock signal creating dubious timing quality. And the more devices you mult, the further off the impedance will be.

    The correct way to mult w/c with BNC "T" connectors is when the inputs can be made unterminated, and you use a 75ohm BNC terminator only at the last device in the chain, like this....

    WC OUT>-------T------T------T-[BNC 75term]

    Plenty of people have mult'd their w/c without observing proper termination, and everything still functioned. But the performance will most likely not have been as good as it could have.
  5. Exsultavit

    Exsultavit Active Member

    Hmmm... clearly, I must find out if the WC inputs can be set up unterminated on the HD24. The other way is with one of those Sonifex boxes, but that is certainly not the cheapest way.

    More soon!

  6. Thomas W. Bethel

    Thomas W. Bethel Well-Known Member

    I am pretty sure you can use a Video DA for the task and those are very easy to find. 75 ohm input and multiple 75 ohm outputs.
  7. Zilla

    Zilla Active Member

    If you are going to spend any kind of money on this, I would suggest going full pony: buy a dedicated clock generator with multiple outputs. This will get better sonic results as well as being less of a kludge in set-up. Nanosync or Big Ben come to mind.
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