Film-Tech Forum ARCHIVE: dolby sdu4 decoder

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Posted by Rajendran Dinesh (Member # 5860) on 09-18-2010, 03:49 AM:

dear friend, i have dolby sdu4 unit, but i did not no any idea for this decoder, any body explain this unit,

dolby sdu4

Posted by Steve Guttag (Member # 268) on 09-18-2010, 06:12 AM:

The SDU4 decoder is a Cat150E in a box. It can force a Mono, Stereo as well as ProLogic decodes. It has XLR IN/Out to work in professional analog audio systems.

Posted by Frank Angel (Member # 248) on 09-18-2010, 03:32 PM:

Sounds like one could use it as an easy way to derive a center surround out of the surround SL & SR channels.

Were these boxes common pieces of equipment? Are they floating around & easily obtained nowadays?

Posted by Steve Guttag (Member # 268) on 09-18-2010, 05:43 PM:

They have been in the "Professional/Broadcast" price book for a long time. There is even an EX box for it.

Steve

Posted by Mark Gulbrandsen (Member # 72) on 09-18-2010, 07:32 PM:

I have seen them on Ebay umteen times for a mere pittance... Keep your eyes open there if you're after one.

Posted by Manny Knowles (Member # 1171) on 09-18-2010, 08:12 PM:

They certainly were common -- the SEU4 was how Lt/Rt tracks were derived from 4-channel print masters. The SDU was used to verify the integrity of the encode.

We had an SEU/SDU pair at USC until we decommissioned "the old building" in Dec 2008. They were replaced by the newer 563/564 combo on each dub stage.

I believe those old SEU/SDU units may have been saved and moved into the older scoring stage there.

So, some are still in use.

Posted by Rajendran Dinesh (Member # 5860) on 09-19-2010, 02:27 AM:

dear friend,may i use this sd4 for surround channels adapter type, for cp55 ,,

regards
dinesh

Posted by Manny Knowles (Member # 1171) on 09-19-2010, 09:48 AM:

Maybe.

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Not if it is for analog sound. Analog (optical) yields a mono surround track -- if you route that signal through the SDU you will still get a mono signal via the centre channel output. In an EX scenario, that would give you surround on the rear wall only (i.e. nothing via the side walls).

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However, if your surround signal is from a digital track, it could work but then you must be aware of which movies are Dolby SRD-EX (or DTS-ES) and which are "standard" 5.1. Otherwise, you will achieve unintended results.

You would also need to provide a means of EQ and amplification for three channels of (LCR) output.

Depending on how your surround loudspeaker array was wired, you may need to make some changes there. You will need them divided into left/right/centre arrays.

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Oh -- and, of course, your CP-55 needs to have stereo surround output -- If I recall correctly, the surround output of the 55 is mono.

Does anyone know if there was an upgrade path for the CP55 to support digital (with stereo surround output) ??