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702T - Pro Tools 002 via SPIDF


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I saw this in another post and rather than hijacking that one I thought it might be better to start a new topic. Apologies if you feel I was wrong in that assumption.

Anyway,

The Sound Devices 788t has eight of arguably the best preamps and ADCs in a portable piece of sound equipment. It also has firewire ports. On top of that it is the industry standard for location based mutitrack recorder: most sound mixers either have one or are at least familiar with their use. Wouldn't it be AMAZING if this piece of equipment could be used as a computer audio interface? All the pieces are there. Its seem like it is only the software that is holding this machine back from becoming a whole new beast.I already use mine for its preamps in my project studio and then run it through a ADC/interface into Pro Tools. This would cut out a whole section of the signal chain that is already there built in to to 788t.

Ed

I've wanted to use my 702T in the same way. It only has 2 channels so SPDIF should work right? What cable/adaptors do I need to make this work? I have a Hosa Digital-Transfer Coax cable which has the RCA-style ends. (male on both ends). Do I just need a BNC to female RCA? I want this to go into the SPIDF input on my 002.

Last question: am I limited to 48k/24bit/stereo? Or can I do 96k/24bit/mono?

Thanks!

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Well, a quick look at both manuals and my experience tells me you should put a BNC-RCA adapter on your 702T, connect your RCA cable, set 702T for SPDIF out and go into PT software and use clock to SPDIF in, not optical..

SPDIF can do 2 channels of 96K.. but of course you already know this, right?

RTFM. A device that is limited at 48k 2 channel doesn't do 96k one channel.. doesn't work that way.

I'm PM'ing you my PayPal email address so you can send me $50.

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Well, a quick look at both manuals and my experience tells me you should put a BNC-RCA adapter on your 702T, connect your RCA cable, set 702T for SPDIF out and go into PT software and use clock to SPDIF in, not optical..

SPDIF can do 2 channels of 96K.. but of course you already know this, right?

RTFM. A device that is limited at 48k 2 channel doesn't do 96k one channel.. doesn't work that way.

I'm PM'ing you my PayPal email address so you can send me $50.

hahaha. thats funny. i did not know that spdif could do two channels at 96k. guess i could've looked it up but i prefer to hear it from you guys. funny that things don't work like 2 ch 48k = 1 ch 96. i mean, makes sense but if it doesn't work that way then it doesn't work that way. good to know.

thanks!

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  • 5 weeks later...

Has anyone who has tried this had any issues with the logic level difference between AESid and S/PDIF? Has any one used a voltage divider when going from AES -> S/PDIF (as suggested here http://www.rane.com/note149.html)? More to the point has anyone who has not used a similar circuit had issues?

There is a menu setting in the 702 for the format of the Digital output (offering the choices "Consumer" and "Professional" to switch between SPDIF and AES3id. I use this all the time for SPDIF with a BNC to RCA adapter and have never had any trouble, into a wide variety of equipment with SPDIF inputs. More complicated is using it in AES mode to feed most professional gear which uses the Balanced AES standard. I have a Neutrik inline AES unbal-balanced transformer for this purpose.

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  • 2 years later...

Very easy to make a voltage divider to pad down AES levels to s/pdif ranges. Done it in a lot of installations. Note this also unbalances the whole cable, but I've never had a problem with that. 

 

As far as using the analog outs... even though this is good equipment, aren't you  burning another set of d/a/d conversions? Each conversion adds distortion, and even though you can't really hear the difference in the field (with good converters), it can become obvious in post. Particularly if dialog is being processed for a broadcast commercial.  

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Yeah I don't think the analog line outs of the 702t are before conversion so a straight out digital approach would be best, i'm looking to do the same thing at the moment with my Lynx Aurora converters. Trying to make my SD pull double duty as my studio pres too (yeesss im cheap I know)

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Well if the pres were analog, they could be post pre like a direct out... But they aren't.

Preamps are always analog. Frequently followed by an A-D converter as an integral part of the inputs. And no, the 744T has no direct outs (what for? It's not a mixer), but you can route an input straight to an output, but... still converting to analog
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Preamps are always analog. Frequently followed by an A-D converter as an integral part of the inputs. And no, the 744T has no direct outs (what for? It's not a mixer), but you can route an input straight to an output, but... still converting to analog

ok some bad wording from me, I am fully aware of how pre's and A/D and D/A works, dude, it was just a wish, no need to get defensive. The AES/SPDIF is perfectly fine.

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