Film-Tech Forum ARCHIVE: CP750 7.1

This is topic CP750 7.1 in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=16;t=002904

Posted by Peter W Schoell (Member # 9755) on 12-27-2016, 03:32 PM:

I have a couple of CP750s set up for 5.1 and I think I would like to convert them to 7.1.
First, will I notice enough difference to make this worthwhile?
I'm using ds200 processors, and the cable connecting them is a big multi conductor with DB25 ends. Can I change the pinout on each end to make 7.1 work? Then where do I get this pinout list? I would also need the pinout for the analog out to the amps. Will this be just a matter of adding 2 conductors for each new channel?

Posted by Dave Macaulay (Member # 813) on 12-27-2016, 07:40 PM:

You notice the difference in a movie with a lot of surround effects that use it.
Odyssey makes a card that does the CP750 DB25 input swap of HI/VI and BLS/BRS for you. Worth the price.
If you have a soldered DB25 output connector to the amps then you would need to add in two shielded pair cables for the two amp channels. Odyssey also makes a CP750 output card with tiny terminal blocks to connect the amp wires to, and it has a parallel DB25 connector as well. You could connect your new rear surround amp signal wires to the terminal block and continue to use the DB25 as-is for the 5.1 channels. Again it's worth the cost - unless you enjoy soldering DB25 connectors.

Posted by Jim Cassedy (Member # 4115) on 12-27-2016, 09:19 PM:

Your CP-750 should have come with a manual on a disk.
Or, if you have access to the Dolby Customer Portal, you can
download a manual from there.

It has a whole chapter (chapter 5) on converting a CP-750 to
5.1, and a complete diagram of the wiring changes you'll need
to connect it to a DSS 200.

But before you start pulling wires & making changes, the manual
states that at a minimum your server software must be v4.2.1 or
higher,and your CP-750 must be v1.2.6.5 or higher.

I've also discovered (the hard way) that there are errors in the pin
out diagrams of some of the earlier CP-750 manuals.
I can't recall exactly what they were, but it took me awhile to figure
it out. Manuals with a version number of "5" or higher seem to be OK.