Grimm Audio CC1, Руководство пользователя

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sync, but fortunately it is going out of fashion. LTC is probably the least stable time
reference around.
Enter digital audio. The audio track now needs to be synchronised to the picture.
Word sync has a better time resolution than video sync, but still the most common
practice is locking the audio clock to the video clock. Even modern digital video pro-
duction practice tends to lock audio to an analogue video signal. This is unfortunate
because low jitter is not exactly a design spec for a video sync generator.
The CC1 cannot slave to video sync directly. In order to avoid direct crosstalk be-
tween the black-burst generator or receiver and the audio clock, we have omitted
video sync functionality. Our best advise is to use the CC1 as the audio master
and slave all video to the audio word sync. If you nevertheless do need to slave the
audio system to video sync you can either buy our VCC ‘Video to Word Clock’ con-
verter or use any other generic video to word clock converter. Connect the retreived
word clock to the CC1’s word clock input and have the CC1 clean up the sync and
distribute clock to the audio devices as usual. The extraordinary stability of the
CC1’s PLL will make sure the result comes as close as possible to making the audio
chain master.
Hints
• Select decent quality 75 Ohm coax cables and certainly do not skimp on the qual-
ity of the connectors.
• Make cables no longer than necessary.
• Cables add propagation delay. It is exceedingly rare for differences in clock phase
to affect the interoperability of connected audio equipment, but if it happens, using
equal length cables throughout helps.
• Disconnect unused gear.
• Ideally do not leave the word clock input connected when the CC1 is master.
Although unlikely (the CC1 has a relay to actively disconnect the input when not in
use), there is a possibility of cross-talk from the input clock to the outputs. Like-
wise, do not leave an AES3 cable attached if not needed.