Film-Tech Forum ARCHIVE: factory splices causing Dolby to cut out..

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Posted by Carl King (Member # 398) on 05-26-2001, 10:30 PM:

Hi Gang;

I've noticed lately that some of the so-called "factory splices" are causing my Doby Digital sound to revert to Stereo for about 3 seconds and then reverting back to Digital. This is new and has happened in more than one house and different prints. Mummy Returns and Pearl Harbor is doing this now. I can cut out the splices and make my own (the factory ones and made mid-image instead of on a frame line) and solve this but I was wondering what causes this to happen.

I assume Mr. Pitlayk can answer this question.

thanks
Carl

Posted by Brad Miller (Member # 2) on 05-26-2001, 11:00 PM:

Unless the actual splices have a printing problem right around the splice, you should not be having this problem. My immediate recommendation is to have the readers calibrated. What kind of reader do you have? Basement reader (and if so what make of projector)? Cat 699, 700 or 701 penthouse?

Posted by Randy Stankey (Member # 64) on 05-26-2001, 11:17 PM:

My guess would be along the same lines as Brad's. But if the thing runs OK when you cut out the lab splice then I'd imagine that a printing problem isn't the cause. (Or at least the major contributing factor.)

My question is: "What error reading is the player running at during the rest of the film?"
If it's running at "6", for example, and a crummy splice goes through that may be enough to cause the system to kick out. If it's running at "3" or so, I don't see why a splice would cause a malfunction.

Whenever I have a problem with a Dolby Digital system the first thing I check is the LED levels. (Assuming you are using a Cat. 701, etc.) As good as LEDs are they still have a habit of tapering off on you. After a few months they usually start to get dim and need a tweek. If you can't raise the voltage high enough you'll have to replace them. It's not hard to do but you will need to use a scope.

If it's not the LEDs (or the lamp) then check the other parameters: Focus, lateral, azimuth, etc.
Even in a penthouse reader you need to check on these at least once in a while. You can use DRAS but if you really want to know what's going on you should use a scope. DRAS is known to have some inaccuracies. My boss had a meeting with Lonny J. from Dolby and he showed my boss a real live demo of how DRAS can say that your reader is running OK but the scope shows it's out of adjustment.

To make a long story short, if you have your reader aligned with a scope and then you make a "reading" using DRAS and remember it, you can use DRAS to verify that the reader is still running OK. But if you try to use DRAS to make the primary adjustments to the reader you may end up with a reader that's slightly out of adjustment.

Posted by Paul G. Thompson (Member # 655) on 05-27-2001, 02:54 AM:

What is your normal error rate? If it is high, you need the reader re-aligned. You could be on the threshold of defaulting, if it just takes one splice to tip the table.

Posted by John Pytlak (Member # 331) on 05-27-2001, 06:04 AM:

Since "Mummy Returns" and "Pearl Harbor" were printed at different labs, it's unlikely both made a change to the ultrasonic splicing technique used on the unprocessed film. I agree with Brad that your reader may need recalibration.

With splices, not only do you lose the data covered up or cut out by the splice, but the splice may cause a brief jump and lateral displacement of the print in the reader. The error correction of the digital system should normally be able to compensate without defaulting to analog.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

Posted by Jon Bartow (Member # 241) on 05-27-2001, 07:15 AM:

DRAS10 (or the new DRAS for the 650) is primarily a film analysis program. And it does that quite well. It can NOT tell you how well the reader is aligned. The only way to align a reader is with a good scope, and some known test film.

Posted by Antonio Marcheselli (Member # 373) on 05-27-2001, 07:54 AM:

Carl,

I always remove factory splices because I hate blank lines in the center of the screen. Usually that type of splices are not good, with the risk to break the film.
Once with HANNIBAL I had a factory splice I didn't saw while builing the film.
When I saw the film the sound defaulted in analog for 2/3 secs (usually no more than 1 sec) and I heard a distortion in the sound...
As soon the show has finished I went in the booth and the projector had its loops all upseted. I rethreat the machine but at the following show, the same.
Well I rewind manually the film to find out that the splice was horrible made: perforations were very close and the film jumped on one or more sprocket (causing the loop mess and the sound distortion). The last part of the film before the splice had also the DD data out of frame causing the DD drop out for few seconds.

I would recommend to remove all factory splices.

Bye
Antonio

Posted by Carl King (Member # 398) on 05-27-2001, 08:02 AM:

Hi everyone:

Thanks for all the advice. The general consensus seems to be that I need my readers calibrated. That's on the "to do" list when my tech guy comes in this month. In the meantime I will take out all the factory splices and advise my relief operators to do the same. I did send a note to Deluxe asking them if it its policy to make splices mid frame at their labs. No response yet.

Antonio. Nice to hear from you. All the way from Italy. Isn't the web great?

Thanks again everyone.

Posted by John Pytlak (Member # 331) on 05-27-2001, 09:48 PM:

Since the lab splices are made in the dark on the unprocessed film before the image is even printed, on average they will be on the frameline 25 percent of the time (1 chance in 4).

Posted by John Walsh (Member # 168) on 05-27-2001, 11:51 PM:

Wouldn't that be one chance in three, since on the "fourth" time, you're back in frame again..?

Posted by John Pytlak (Member # 331) on 05-28-2001, 11:34 AM:

Since there are four perforations per frame, with pure chance the splice would be on the frameline 1 time out of 4 (25%), and off the frameline 3 times out of 4 (75%).