Film-Tech Forum ARCHIVE: CP-200 Mag Input for Split Surrounds

This is topic CP-200 Mag Input for Split Surrounds in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Rich Ferrando (Member # 2056) on 01-10-2005, 01:47 AM:

I'm looking to try to attach some "easy-to-use" (aka "Hey dummy get away from my amps") external inputs to our existing processors for video projection rentals. And since I want to make things difficult, I'd like to be able to input multiple channels.

In one of our houses, we have a CP-200 without an accessory unit. I was planning on inputing the external sources through the Mag inputs. However, I'd really like to have split surrounds. Now, I know that the CP-200 is capable of doing stereo surrounds for 70mm via Format 43, but at least in the manual anything dealing with stereo surrounds is mentioned in the same breath as the Accessory Unit, which we don't have.

Now, my questions are:
- In 70mm mag with stereo surrounds, are the two surround channels simply in place of the Le and Re channels, and thus inputing a DVD player's left and right surrounds into the Le and Re inputs and choosing Format 43 will pump that signal through the P and Q outputs? Or is the Accessory Unit required for this?

- If the Accessory Unit must be in place for that, is there anywhere else on the Control or Processor units where I can input my surrounds into the P and Q channels?

- The Mag inputs on the CP-200 list a maximum input voltage at 100mV or 1V (internally selected) for Dolby level, at 50k ohnms impedence. The DVD player we'd be using outputs line level at 2V (rms) and 10k ohms impedence. Will this voltage fry the circuits on the Magnetic input card and thus burn my dreams into cosmic dust, leaving nothing but Squadu?

Posted by Steve Guttag (Member # 268) on 01-10-2005, 03:38 AM:

For your purposes, no you don't need the Accessory unit. However, no, you can't just select 43 and use the Mag input either. Le, and Re are just that. Format 43 did not simply reroute them. The P and Q information was extracted from them in the Acc. rack and mixed with the S channel to make the composite P and Q channels.

Your DVD player is likely to output -10dBV nominal if it is on RCA type connectors. I'm not sure where your 2V spec comes from unless it is a maximum.

Your best bet is to explore "JM10" and make use of the optical stereo surround command line to switch P & Q to look at JM10. I believe you will need to make links and remove some on "Special 2" for this. This will be a 300mV input and the Mag input will be a 100mV source (for the remaining channels) so you will need to pad down the other inputs (use Le/Re for the subwoofer input).

Another way that probably would be easier is to obtain a DTS D567 board, hook your DVD player up to the DB25 connector, connect JM11/21 through it and have a 5V supply on a switch to switch the DVD player in and out.

There are always possibilities with the CP200 if you look hard enough.

Steve

Posted by Chris Trainor (Member # 9) on 01-10-2005, 12:30 PM:

I did the 'use the mag inputs' approch with some success.. tho not the best for obvious reasons. I used the Le/Re for LeftSur/RSur inputs and setup a custom format to remove NR and set stereo surround. Not the best as I'm sure it's not sending full channel to the surrounds but seems to work OK.

If I could find a copy of the processor/control head schmetatics I could probably come up with a more useful solution but no joy on that front yet. [Frown]

Using the DTS box seems to be the easiest route tho... I might try that myself.

--Chris

Posted by Rich Ferrando (Member # 2056) on 01-10-2005, 01:46 PM:

I forgot to mention that we also have a Cat 493 installed on the CP200. Would the DTS board interfere with this?

I could theoretically patch the DVD player's outputs into a DB25 for the Cat 493, but my goal was to avoid having to go behind the rack and disconnect things.

EDIT--

And the 2V spec comes from the manual for my Sony DVP-S560D. It lists all RCA outpus at 2Vrms, 10k ohms.

Posted by Gordon McLeod (Member # 33) on 01-10-2005, 10:24 PM:

As steve said the format 43 method will not work and still would address getting the dvd sub woofer track through the processor
I have often wired a normalized jack field into the rack in the jm11/jm21 loop for the access point for a DA88 for dailies