Firstly, with regard to optical changeover. In the manual it indicates that changeover can be controlled with pulsed contacts, as opposed to the traditional maintained contacts. Obviously this would save me a wee bit of wiring, and time is very tight on this job. The CP500 also had this capability, we used it once and quickly converted that install to maintained contacts, due to the famous CP500 reliability. Has anyone got any experience, good or bad with this function of the CP650? For my tuppence worth, I've found the CP650 to be a hell of a lot more stable than it's predecessor.

Secondly, with regard to SR.D changeover. As I'm sure you all know, if using basement readers on a DA20/CP500, one can dispense with the motor start contacts, leaving M1 and M2 closed, I can't remember why this works, just that it does. Something to do with the amount of SR.D data on leaders and the perf delay of a basement reader. Anyroad does anyone know if the CP650 behaves the same way? I don't see why it wouldn't, but you never know!

As to dispensing with the motor start relays...it isn't anything Dolby would recommend but more of a happy circumstance owing to the extremely short delay on the basement readers (typically around 20 perforations, whereas the DD data is something like 16 perforations ahead, there would only be a 1-frame discrepency). It is something I wouldn't do so I can't advise you on the ability to do it on the CP-650.

As to going with a latched changeover on the CP-500...that is the least reliable method. The CP-500 can "forget" what machine it is on and can only be brought back into sync with a complete cycle between the two projectors. For this reason, I've switched my installations to "pulsed."

One thing I don't like about the CP-650's display is that the "motor" information has a "M" permanently displayed with either a 1 or 2 or both (12) after it. For platter houses, loose the display. For changeover houses...having it read M12 is also stupid. Rather than have a the DB9 jumper (pins 1 and 5) just have a dip switch setting or a jumper on the back.

Steve

Hmm, never had any trouble from my CP500 changeovers with latched contact installs. Mind you I carry out the mod that removes software control of change-over as a matter of course, it's just one less thing to go wrong with these things!

"As to dispensing with the motor start relays...it isn't anything Dolby would recommend" Point of fact it was Dolby that told me about this in the first place! I'd never noticed that about the display, yeah M12 doen't make any sense at all.

As to not having two projector inputs...I doubt it will ever happen. All of the studios are 2-projector on their rooms. The extra cost of overhead for the 2nd optical input is very low.

Steve

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