my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Strange connections to CP-65

Author Topic: Strange connections to CP-65 Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 07-08-2007 04:57 AM                     I had cause to download the CP-65 installation manual yesterday; I just needed to check a jumper setting on the exchange Cat.441 card that had just arrived. This card seems to have solved the last remaining sound problem that we had with the digital system, but we don't have any films on digital in the next few weeks. I don't have the equipment to set up the EQ, but it sounds ok, and they are putting in new amps next week, so a full B chain alignment will presumably be done then anyway. While I was waiting for the last show to finish last night I was looking through the manual, and saw something strange which I hadn't noticed before. Its on page 2-5, the wiring diagram for the CP-65 300 configuration for running format 42. There are two outputs on the CP labeled pre amp outputs Lt and Rt. These are unused in the standard configuration, but are marked 'To Switching in Mag Pre-amps' in the CP-65 300 configuration. I cannot think of any possible reason for this. There are three things which are switchable in the MPU-1, the use, or otherwise of the 12kHz. surround switching system, controlled only by a local switch on the Cat.93 card, and the projector changeover and 35/70mm selection, which can be controlled remotely, by grounding a terminal to switch to projector 2, or to 35mm. Lt and Rt pre-amp outputs seem to have nothing to do with either of these, so what are these connections for? I suppose it's just about possible that you could use the presence of the pre-amp signals to indicate that a 35mm print is being run, but you would need external circuitry to operate a switching relay, and it would only work with a mag-optical print, in which case only one channel would have any output, so why connect both? It wouldn't work at all with a pure magnetic print, and there have got to be easier ways to get the CP to tell you when it's running format 42 anyway, so I don't think that can be the reason. Did many places ever run this configuration? 70mm houses always seemed to have a CP-200. It's highly unlikely that I would ever want to do this; I'm just curious.  |  IP: Logged Ben Wales Jedi Master Film Handler Posts: 602 From: Southampton. England Registered: Jul 99 posted 07-08-2007 05:51 AM                     quote: Stephen Furley Did many places ever run this configuration? 70mm houses always seemed to have a CP-200. Yes, I know of a CP65 that was installed at Harbour Lights in Southampton. When I was there (1995) the 70mm mag was selected through the Aux imput (CP65) and a additional external format selector switch for the 70mm formats,the 70mm format 42 & 43 signal path was routed back into the Cat22's, this was a 3 + sub channel stage speaker system. I recall you could not check the Dolby Levels for 70mm without a RTA, so it was only done on a few occasions by our service Tech.  |  IP: Logged John Hawkinson Film God Posts: 2273 From: Cambridge, MA, USA Registered: Feb 2002 posted 07-08-2007 09:29 AM                     On the CP65, TB2 positions 11 and 12 are the optical preamp outputs (left and right) from the Cat. 240A before noise reduction. They are quite handy to have available on a booth monitor selector, particularly when playing old or noisy prints, to listen to the nature of dirt and scratches if you're wondering why the NR'd print sounds strange. They are also handy for, say, listening to buzz track while doing A chains. (Of course there are other ways to do these things, too.) --jhawk  |  IP: Logged Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 07-08-2007 10:50 AM                     Yes, that's the connections, TB2, 11 and 12; should also be useful, along with the mag/aux inputs, as send and return for other external processing for special formats, like Perspecta, or dbx noise reduction. But why does the CP-65 300 wiring diagram label them as going to 'Switiching in mag pre-amp'? I did wonder if I had mis-understood it, and it meant that these signals were being sent to the MPU to be switched, rather than being used to switch something in the MPU, but that wouldn't seem to make any sense either.  |  IP: Logged

All times are Central (GMT -6:00)

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.