rec.arts.movies.production.sound

On Aug 13, 8:41 pm, MitchB4610 wrote:
> On Aug 13, 6:56 pm, Blas wrote:
>
> > Should I decide to include a BNC cabling feed (as part of this
> > "breakaway" cable I'm gonna have created), it wouldn't be solid core,
> > as all the pairs are braid wire. Will that have a negative affect on
> > the purpose of the BNC? I know it doesn't carry video signal, but syn/
> > timecode. Am I confusing issues here? Someone I talked to said BNC
> > carries a 4 or 5 volt current. Should that be the case, wouldn't that
> > cause issues with the audio runs?
>
> Blas, A "BNC" connector -- per se -- doesn't "carry" anthying --- it
> is a connector type. Just like XLR doesn't carry anything -- it's a
> connector type. The only reason (that i can think of) for a sound
> mixer to have a "channel" in their umbilical (breakaway) that
> terminates with a BNC connector -- is to tap TC off camera. TC is
> audio, data transmitted in bursts of tones, in much the same way
> fax machines transfer data over telephone lines. You've heard the
> howls and screams of fax machines trying to connect with each other --
> same kind of thing. The folks telling you that "BNC" carries a 4 to 5
> volt current over a solid core cable are talking about video. YOU DO
> NOT WANT THIS IN CLOSE PROXIMITY TO YOUR AUDIO PATH -- . IN YOUR
> BREAKAWAY CABLE.
> But as I said before -- If you are wishing to sync your HD-P2 to a
> free run TC source -- you don't need this. Jam sync it. No "BNC"
> cable needed.
> Mitch

This last sentence is incorrect and possibly dangerous information.
You can jam-sync an HDP2 recorder's TC generator to an external
source, but the internal clock of the recorder is far too inaccurate
to hold acceptable sync for longer than a few minutes--15 min tops I'd
say. The P2 will record very accurate TC but it needs to be either
clocked from an acccurate external source via word clock or via TC.
I've used the P2 on film sound jobs with a Denecke SB2 external TC
generator feeding the P2's TC in (and being its clock source) as well
as jamming the slates from it. I've done MANY video jobs with it
using either hard-wired or wireless TC from the video camera or deck
(which can allow you to run in record-run TC mode, as specified by
almost all prod co.'s in my area). The TC aspect of the P2 works fine
in this way--but it is not like a Sound Devices etc recorder which has
a very accurate clock of its own. I can guarantee you that if you do
a straight jam+disconnect of the TC w/ the P2 and a video camera or TC
slate that you will have out ot sync audio in post unless you rejam
every 15 min or so.

Philip Perkins CAS