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Author Topic: Capturing Dolby A, SR audio on a film scanner Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 02-12-2015 09:01 AM                        MWA-Nova and Lasergraphics make 35mm digital optical readers for their scanners for everything except SDDS, too.  |  IP: Logged Paul Gordon Jedi Master Film Handler Posts: 580 From: Ottawa, Ontario, Canada Registered: Aug 2005 posted 02-12-2015 09:42 AM                        Good to know but we are stuck with a DFT Scanity. Two years ago very few scanners (not telecines) had sound head capture options.  |  IP: Logged Paul Gordon Jedi Master Film Handler Posts: 580 From: Ottawa, Ontario, Canada Registered: Aug 2005 posted 03-16-2015 05:41 AM                        Ok we found a decent CP-65 with Cat 350 SR cards. Our problem is the Sondor head on the scanner has a preamp and the stereo signal is way to hot. Any ideas of an easy solution. Is there a way to bi-pass the Cp-65 preamp card and still get NR and 4.1 out? Pulling the card does not seem to work as nothing flows through the other cards then. I'm going to talk to Sondor but jut though you guys may have a good idea. BTW this will be an issue with all film scanners. They may say they can capture Dolby A, or SR but all they do is give you an un-decoded stereo track with no NR!  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 03-16-2015 06:14 AM                     Pad it. The analog optical track is only L/R, encoded with Dolby SR noise reduction. It is usable without any decoding, applying A decoding eliminates some of the SR encoding artifacts, and SR decoding is ideal. Reader signal response and EQ is important, level matching is required.  |  IP: Logged Paul Gordon Jedi Master Film Handler Posts: 580 From: Ottawa, Ontario, Canada Registered: Aug 2005 posted 03-16-2015 08:25 AM                        Yes we could pad the incoming hot signal but a jumper that bi-passes the preamp on the Dolby might be a better option. The difference in signal strength is huge like 50db  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 03-16-2015 08:52 AM                        Perhaps bypassing the Sondor preamp is the answer. The output of your red LED works directly into the Dolby input. It would look just like any other soundhead.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 03-16-2015 12:14 PM                     Unplug the CAT240A and then connect up to the Optical Preamp Outputs...you'll be at a 388mV buss level there. You can also come in on the "Mag" inputs and configure the CAT443 appropriately to get everything switched as you like. Another handy trick that works with most any Dolby optical preamp is to use 47K resistors to each optical preamp terminal (one on the + and one on the -) to your source. They will knock down the level to approximately consumer level -10dBV. It is important that you use a resistor on each terminal and not just the + ones. Particularly on the CAT240A, which uses non-transformer inputs.  |  IP: Logged

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