Film-Tech Forum ARCHIVE: making CP650 Analog Cable

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Posted by Garrett Oliver (Member # 9103) on 03-29-2016, 07:12 PM:

I need to make some 25pin Analog out cables for our CP650 and I know that each wire needs to be ground to the chassis. Does anyone happen to have a picture of a completed 25 housing? I want to make sure that what I am thinking is the correct way.

Posted by Dave Macaulay (Member # 813) on 03-30-2016, 06:00 AM:

Sorry, no picture. The wiring is simple: doing it so it fits in a shell and looks decent isn't so easy.
If you use individual shielded pair cables for the signals (advisable) then connect the shields to ground at the amplifier end, drop them at the processor end. This avoids shield current and makes termination a bit easier. For cinemas the processor is usually in the same metal rack as the amps so using the recommended toothed lockwashers to ground each unit will avoid any ground potential differences. Otherwise a stout wire should connect their chassis together.
Beware of the EX oddness with the 650: with an EX card installed the surround outputs come from the "Option Card I/O" connector, there's no usable signal on the main output connector surround pins. Connections get more odd if you use the internal crossover card.

Posted by Sam D. Chavez (Member # 1841) on 03-30-2016, 11:30 AM:

Dave describes it pretty well esp. the EX connector.

Odyssey Products in GA makes all sorts of adaptors to make this all easier. I would give them a call,

Posted by Scott Norwood (Member # 30) on 03-30-2016, 12:38 PM:

For whatever it's worth, I have used Gepco GA61806GFC (6 pair) or GA61808GFC (8 pair) cable for this sort of thing (there are individual shielded pairs within the cable). This is intended for making audio "snakes," but works well for this application. For connectors, I have used Amphenol L717DB25P or L77DB25S with 17E-1657-25 hoods. It is somewhat difficult to find DB25 hoods that will accommodate large-diameter cables, and the 17E-1657-25 is the only one that I have found that will. All of these parts are available from Digi-Key and probably elsewhere.

The annoying thing about the CP650 output (aside from the connector change when the EX card is used) is that there is no separate "monitor" output connector, so you need to figure out a way to "Y" the output somewhere, preferably without unbalancing the signal or putting the monitor itself in the signal path (unless you are also using it as a crossover or have some other reason for intentionally putting it in the signal path).

I have always connected the signal grounds at both ends and have not had any issues, but I realize that this is not necessarily advisable in all (any?) cases.

The Odyssey boards are a good idea, especially if you want to make use of the AES input on the option I/O connector. They give you both DB25s and screw terminals, which makes connecting both a monitor and amplifiers easy.

Posted by Steve Guttag (Member # 268) on 03-30-2016, 02:25 PM:

I've always used Belden 1510C or 1410R (depending on 5.1 or EX) and Amp brand Dsubs (crimp connections). Still do on CP750s.