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Gear / Technical Help => Recording Gear => Topic started by: tim in jersey on September 19, 2017, 08:13:03 AM

Title: SD 7xx wierd quirk
Post by: tim in jersey on September 19, 2017, 08:13:03 AM
So I had a show 1.5 weeks ago where I used my 744t and took an AES/EBU output from the  SBD  which was outputting 44.1/16 bit. I would have preferred a 24 bit signal, but beggars can't be choosers.

Ran my 744t deck again this past weekend using strictly analog inputs on all 4 channels, and when I loaded up the files in my DAW I was surprised to see all 4 channels were set to 44.1/16 bit.

Guess the digi-input supersedes any sampling/bit rate settings on the deck and needs to be manually reset after the fact.

Just a word of caution...

Title: Re: SD 7xx wierd quirk
Post by: nak700s on September 19, 2017, 12:11:04 PM
Didn't you have to set the rate for the initial board patch?  Is it possible it was already set at that rate (maybe you reset or something)?  I know when I record from one show to the next, as long as I don't mess with those settings, they stay as they were...and I patch out of boards all the time, but through the line ins.
Title: Re: SD 7xx wierd quirk
Post by: tim in jersey on September 20, 2017, 10:07:04 PM
Didn't you have to set the rate for the initial board patch?  Is it possible it was already set at that rate (maybe you reset or something)?  I know when I record from one show to the next, as long as I don't mess with those settings, they stay as they were...and I patch out of boards all the time, but through the line ins.

I have to test further. I have a V3 with an AES/EBU out. But it seems like the AES mucked with my settings. I've only ever grabbed analog SBD patches with this unit but I'm fairly certain that it clocks to whatever the AES/EBU is outputting. I have to read the manual a little more, test, and maybe send an email to Sound Devices.

I do know this: when I was connected to the console the 744 showed a message that said "LOCKED". Fortunately I didn't bomb the recording, but I found this to be interesting.

I'll report back when I know more.
Title: Re: SD 7xx wierd quirk
Post by: nak700s on September 22, 2017, 02:32:21 PM

I do know this: when I was connected to the console the 744 showed a message that said "LOCKED". Fortunately I didn't bomb the recording, but I found this to be interesting.


LOCKED? I've never seen that one before, but would love to know how to lock mine up when recording so I don't accidentally do something stupid.
Title: Re: SD 7xx wierd quirk
Post by: yug du nord on September 22, 2017, 04:10:02 PM
^I think that means that the deck's clock is LOCKED to the DSBD's clock.
Title: Re: SD 7xx wierd quirk
Post by: hi and lo on September 23, 2017, 11:48:45 PM

Guess the digi-input supersedes any sampling/bit rate settings on the deck and needs to be manually reset after the fact.

It doesn't affect bit depth. From the manual (pg. 15) (http://cdn.sounddevices.com/download/guides/744t_en.pdf):

Quote
When a digital signal is present, the 744T will lock its sampling rate to the source frequency. This is
indicated by a highlighted block on the main LCD display to the right of the bit depth and sampling
rate indicators. Recording bit depth is not affected by the external digital source.

I don't have an explanation for what you've observed, but can definitively state that the recorder will not automatically change bit depth.