Film-Tech Forum ARCHIVE: DTS going to Dolby SR instead of non-sync?

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Topic: DTS going to Dolby SR instead of non-sync?

Michael Barry
Jedi Master Film Handler

Posts: 584
From: Sydney, NSW, Australia
Registered: Nov 1999

posted 11-14-2000 07:35 AM

We have a CP-65 and a DTS-6 unit, and once the feature's DTS time-code ends, the CP-65 goes into Dolby SR instead of non-sync, so you hear the terrible sound of the tailpiece going through the optical soundhead instead of music. (It's actually preferable to SOME music I've heard, but I digress...).

Additionally, if the feature plays in SR, the CP-65 goes back to non-sync just fine - it's only a problem when playing in DTS. Any suggestions on adjustments that can be made to correct this problem?

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Dustin Mitchell
Phenomenal Film Handler

Posts: 1865
From: Mondovi, WI, USA
Registered: Mar 2000

posted 11-14-2000 08:32 AM

Stupid question, but you have automation right? I mean, the cue is telling the processor 'end of show?'

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 11-14-2000 09:51 AM

When you say DTS6 that is an older two drawer unit.
This was a problem but I believe the firmware update should stop that problem
At the end of the film when the timecode ends the older dts switched to sr or a as all they assumed was there was a print flaw not the end of the feature

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Randy Stankey
Film God

Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99

posted 11-14-2000 10:21 AM

I had that problem in the older DTS units. What I found was that there was DTS code at the tail of the film.

After your tail cue, look at the film and see if there is code. What happened to me was that the machine was seeing that code and switching BACK to DTS. Then the film ran out and then there was noise.

Solution? There are three possible ones depending on your situation. The easiest is to put on another tail cue. (If your automation system will let you) That way you can make sure that it's in Non-Sync as it tails-out. Just look for the very last of the DTS code and put it there.
You can also cut off the tail piece after your tail cue and put on enough black mylar leader for the projector to tail-out safely. That way there's no chance of the DTS seeing the code 'cuz it's not there. The last, (and least desirable) solution is to take a black marker and blot out the DTS code. I wouldn't do that one unless I had no other choice. (It takes a long time to do and it alters the film permantly)

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Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99

posted 11-14-2000 02:14 PM

This is very simple. Your shutdown cue is too early. For example, your automation pulses the CP65 into non-sync and then a few seconds later, the DTS machine stops seeing timecode, so it doesn't know any better and pulses the CP65 back to SR for "analog backup". You must make sure that the DTS timecode drops out BEFORE your automation pulses it's end of show cue into non-sync.

All of the older players exhibited that minor issue. I'm not sure if upgrading firmware will solve that or not, but I'll bet Karen does.

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Michael Barry
Jedi Master Film Handler

Posts: 584
From: Sydney, NSW, Australia
Registered: Nov 1999

posted 11-14-2000 08:41 PM

Thanks everyone! Knowing that the older DTS-6 units default to SR or A, it all makes sense now. If the automation pulses back to non-sync after the DTS code has run out, there won't be a problem.

I will try the methods suggested above and see what works. The firmware upgrade would probably be the most elegant solution, if it's possible...

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Michael Barry
Jedi Master Film Handler

Posts: 584
From: Sydney, NSW, Australia
Registered: Nov 1999

posted 11-15-2000 07:02 AM

I've emailed Karen at DTS about a firmware upgrade - tonight I tried placing an extra cue at the end of the last timecode and telling the automation to go to non-sync at this point, but still no dice...I will have to experiment some more and see what happens on subsequent runs. There's a gremlin in there somewhere.

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Carl King
Expert Film Handler

Posts: 199
From: Saint John, New Brunswick, Canada
Registered: Mar 2000

posted 11-15-2000 01:30 PM

Michael:

I have had your problem. The differance was that in my system the format would revert to SR and then back to Digital.

Thanks to Gordon and the others on this site I now know why.

I'll try Brad's idea and place the cue a bit further away to see if it helps.

Carl King

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Rick Long
Jedi Master Film Handler

Posts: 759
From: Toronto, Ontario, Canada
Registered: Nov 1999

posted 11-15-2000 04:52 PM

When using the DTS-6 with Cinemecannica projectors, one inexpensive way I have used to solve this problem is to fish a two-conductor cable from the projector base to the sound rack.

Cinemeccanica projectors had a set of micro-switch driven contacts that closed whenever the change-over opened, and vice-versa. (Terminals 36 and 37 I think). These were intended to control old mono systems.

I use these terminals to interupt the DTS pulse to Optical, once the change-over has closed.

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Joseph Pandolfi
Expert Film Handler

Posts: 213
From: Milford, CT.
Registered: Nov 1999

posted 11-15-2000 08:12 PM

We had the same problem some time ago. We corrected it by setting the delay in our automation from 8 to 24 seconds (the maximum) after the end cue. This will allow enough time for the CP65 to fallback to SR and the automation will kick it into non-sync. Also our sound is turned off the same time the changeover closes so you won't hear the "bot-dom-ba-dot-ba-dom" as the tail goes through the sound head.

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Karen Hultgren
Master Film Handler

Posts: 492
From: Agoura Hills, CA, USA
Registered: Mar 2000

posted 11-16-2000 04:25 PM

For your CP going to SR instead of NONSYNC at show end:

If it is a DTS-6 (2-drive unit), be sure you are using DTS logic boards with circuitry on them and not just traces (that's the old style). The traces-type baord will not let your stay in NONSYNC at show end. If you have the old board, let me know the CP model, quantity, and your mailing address. I'll send you free replacements.

If it is a DTS-6D (3-drive), be sure no sound cues are added to the film at show end. The movie discs are already programmed to pluse the CP to NONSYNC at the show's ending.

Does this happen with all shows or one in particular?

Please advise via email.

Karen at DTS
khultgren@dtsonline.com

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