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Topic: CP650 sound "wow" on changeovers running Dolby Digital...

Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002

posted 05-24-2012 09:44 AM

Dammit, Tony! I want this resolved!

Thanks for reminding me -- the incoming projector -- it's been a while.

So I'm thinking then the issue will reside with cabling to the processor or the processor itself -- some kind of "crosstalk" between the motor sensing cables or circuits -- Somehow, that processor is "getting distracted" by the incoming projector -- but you swapped out processors, so it's probably the cabling.

[That other processor works perfectly in a changeover situation somewhere else, right?]

I know you did a basic check to make sure the cables weren't wrong-way-round, but if you haven't done so yet, it might be time to take a close look at the connectors..?

I'll re-read the thread so I don't suggest things that have already been suggested, but in the meantime -- what happens if you only start the motor on the incoming projector, but don't make the changeover -- (from somewhere in the middle of the playing reel, so you don't run out of film) -- does the sound stabilize when the other projector finally gets to speed?? And if you stop the incoming projector, does the sound "wow" with the "coast down?"

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Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002

posted 05-24-2012 11:50 AM

Two more questions:

What happens to the motor indicator lights on the front panel of the 650 when you start the motor of the incoming projector? Any sign of gremlins at work there?

What happens if you take the affected CP650 to the other cinema? You brought the 2nd processor to the freaky booth. What about the other way round?

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Mark J. Marshall
Film God

Posts: 3188
From: New Castle, DE, USA
Registered: Aug 2002

posted 06-04-2012 05:48 AM

Anyone else want to bet that either:

1) This never gets solved, or
2) It magically goes away some day

?

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Brent Francis
Film Handler

Posts: 84
From: Toronto Ontario Canada
Registered: Nov 2008

posted 06-04-2012 09:53 AM

HaHaHaHaHaHa

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Tony Bandiera Jr
Film God

Posts: 3067
From: Moreland Idaho
Registered: Apr 2004

posted 06-04-2012 01:11 PM

Manny my amigo:

Cabling and connections have all been ruled out as there are no issues there and there are no influences that could affect them, the front panel motor start and changeover indicators show no gremlins, and due to current circumstances there is no way I can swap the processor out to a known-ok room. As mentioned in a previous post, I blew a perfect opportunity by upgrading my own processor with the latest software before I took it in for the test. [Roll Eyes]

Now, as for the mid-reel start and stops you suggested they seem to have no effect at all. But remember that the way Dolby Digital data is read and "cached" at reel transitions (To cover the effects of splices in platter ops and the duplicate data read on incoming reels heads in a changeover op) is part of the reason I am convinced that software is the problem. (Unlike DTS, Dolby Digital will NOT transition to the incoming reel if the processor is NOT seeing a valid changeover signal. DTS WILL jump to the incoming reel audio regardless of changeover status as soon as the incoming reels' timecode is valid.)

Mark, the odds favor #1 at this point as I still cannot gain access to the room for more tests and my own test print doesn't really have the right end-of-reel content to hear the problem.

And since the University has cut back even more on the screenings that leaves even less chances of solving the problem.

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Mark J. Marshall
Film God

Posts: 3188
From: New Castle, DE, USA
Registered: Aug 2002

posted 06-05-2012 05:58 AM

quote: Tony Bandiera Jr
Now, as for the mid-reel start and stops you suggested they seem to have no effect at all. But remember that the way Dolby Digital data is read and "cached" at reel transitions (To cover the effects of splices in platter ops and the duplicate data read on incoming reels heads in a changeover op) is part of the reason I am convinced that software is the problem.

You are correct, sir. [Smile]

quote: Tony Bandiera Jr
Mark, the odds favor #1 at this point

You are correct again. [Smile]

Don't feel too bad. The people I worked for never figured it out either.

Fear not, however. In about a year or two, if we're all still here and film is still being used somewhere, someone else will either post a new DOLBY WOW thread or revive this one, and we'll start again. [Smile]

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Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002

posted 06-05-2012 09:50 AM

quote:
Now, as for the mid-reel start and stops you suggested they seem to have no effect at all. But remember that the way Dolby Digital data is read and "cached" at reel transitions (To cover the effects of splices in platter ops and the duplicate data read on incoming reels heads in a changeover op) is part of the reason I am convinced that software is the problem.

Okay. Just checking -- when things aren't working the way they're "supposed" to work, I do like to experiment to rule things out.

So, did you "down-date" the software? And FWIW if you're interested in upgrading to 2.3.6.6 -- that is known-working in my unit here at IU Cinema.

Did you ever get the 2nd replacement Cat. 773 card? >meow<

[Edit -- never mind -- I went back and re-read -- you tried with cards from the other unit.]

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Tony Bandiera Jr
Film God

Posts: 3067
From: Moreland Idaho
Registered: Apr 2004

posted 06-06-2012 12:29 PM

Mark:

Yep that's how I see it happening. Even Dolby doesn't seem to care about the issue to pursue it further. (With film going away can't say I blame them, but it is annoying to spend so much money on something that doesn't work right.)

Since they are not running much film anymore it looks like it will become a non-issue altogether.

Manny:

Nope, no chance to "downdate" the software yet, and probably never will at the way things are going over there (politics I cannot discuss in an open forum).

The 773 was a loaner from Dolby so no replacement, but as you saw I did use one from another processor.

So it will look pretty but most likely not be used much if ever.

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System Notices
Forum Watchdog / Soup Nazi

Posts: 215

Registered: Apr 2004

posted 08-10-2013 11:38 PM

It has been 430 days since the last post.

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Tony Bandiera Jr
Film God

Posts: 3067
From: Moreland Idaho
Registered: Apr 2004

posted 08-10-2013 11:38 PM

quote: Mark J Marshall
Fear not, however. In about a year or two, if we're all still here and film is still being used somewhere, someone else will either post a new DOLBY WOW thread or revive this one, and we'll start again.

Guess what? You were right. [Smile]

I can report a resolution to this problem..sort of.

Thanks to another tech at Dolby, I think I finally have the definitive answer to the problem.

First off, it must be stated that Dolby Digital looks at the digital track data in advance of the actual "sync point" (thus the need for a perf delay even with basement readers)..keep that thought in mind.

So what is happening in my case is that the last few seconds of sound data, due to the normal design delay (which is aggravated in my case by the extra delay needed due to the penthouse location), is always read off of the INCOMING reel, so of course the processor will clock to that data regardless of changeover/motor signal position.

In simple terms, the system is working as it is supposed to.

The solution in my case will have to be to shorten the acceleration times on my projectors to help eliminate or mask the issue.

A moot point in any event since I no longer work for the University anyways. Maybe my "replacement" will find this thread and post and fix it. Or not. [evil]

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