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I'm sure there are many of you out there that use this card as a primary means of getting audio into the box. I've only recently started using it, and so far I thoroughly enjoy it. My main question is a pretty simple one -
When syncing the clock, with this unit is it best to use the clock input to sync to another device or is it best to sync to one of the incoming digital signals? Or do you find that it makes no difference. (My thought is probably that last one.)

Just curious.

J...

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DavidSpearritt Tue, 02/08/2005 - 12:36

Yep, I agree. I have found that clocking the AES16 from the first AES pr of the Genex GX8000 is fine when bringing in all 8 channels. I would prefer to externally clock the Genex from the AES16, but haven't bothered to get the cables sorted out. Clocking from AES streams can cause problems, in my experience, external clocking never has. Also use a DAC-1 for monitoring.

FifthCircle Tue, 02/08/2005 - 20:08

David-

What have you found to be the issues with clocking off an AES stream? Of course when dealing with multiple digital sources, an external clock can be a godsend, but for basic work, I've found AES to sync just fine (now ADAT is another issue entirely).

If I had 2 sets of converters that I had to input to the AES-16, I would likely use the one with the best clock as my clock master. Additional converters would be clocked to the clock out of the main pair and the AES-16 could clock either through a WC through, a 75 ohm BNC "T" connector, or via AES. With the transport of a digital signal, as long as they are syncing, you should be fine. Monitoring through a jitter-immune DAC will make it even less of an issue.

The AES-16 SRC also has some pretty darned good SRC as well... when clocking doesn't work, you can clock the card internally and have it SRC by a fraction of a percent your signal and it effectively removes jitter from the signal... I have yet to hear a difference between the sound with and without the SRC, but sometimes it saves me with interfacing multiple digital devices.

--Ben

DavidSpearritt Wed, 02/09/2005 - 02:05

FifthCircle wrote: David-

What have you found to be the issues with clocking off an AES stream? Of course when dealing with multiple digital sources, an external clock can be a godsend, but for basic work, I've found AES to sync just fine (now ADAT is another issue entirely).

If I had 2 sets of converters that I had to input to the AES-16, I would likely use the one with the best clock as my clock master. Additional converters would be clocked to the clock out of the main pair and the AES-16 could clock either through a WC through, a 75 ohm BNC "T" connector, or via AES. With the transport of a digital signal, as long as they are syncing, you should be fine. Monitoring through a jitter-immune DAC will make it even less of an issue.--Ben

Ben, we have found that when there are multiple sources/channels its best to externally clock from a common point ie the recorder when both recording and playing back. I seem to remember in the early days with our Prism bit splitter and the DA88, that when we clocked from AES streams things got clicky. But I agree that for simple stuff like stereo its fine, ie only one stream involved.

FifthCircle Wed, 02/09/2005 - 07:14

I'd say those issues were more a function of the Prism bit splitter and DA-88... Great technology for the day, but a pain in the butt to implement. (never mind the other hardware implementation issues that had a tendency to creep into the Prism- all of them I've used have a burst of sound when you start playback while it tries to sync the bit-split streams). TDIF is horrible for clocking as the original implementation did not carry clock on the signal. Later implementations did cary clock, but only if all connections fit the new spec. Even new Tascam gear often did not fit their own specs.

AES certainly does carry clock information and 4 AES streams from one place shouldn't be any more of an issue than a single stream from one place. (ie 8 channels off of one converter). The sync issues come in when you have multiple sources. Then, I find that either a combination of AES and WC or just WC connections make the implementation *much* easier...

--Ben