Back when the various studios had their preferred digital formats and roll around digital racks were more in vogue...I designed and built the Cardinal MDI-6555 digital interface for the both the CP-65 and CP-55. The board would attach to the backplane of either processor though it had to be "stuffed" for the specific processor.

The MDI-6555 would allow up to three 6-channel digital sources feed the single digital (or AUX) input.

The MDI-6555 also fixed the problem of the DTS player aquiring its digital, selecting digital and then having the automation take the sound out of digital when the douser opened at the start of a show. Likewise it nixed the problem of tail-outs by the automation selecting non-sync and having the DTS player "fault" to its back up optical format after the rating strip ran through.

Here is the prototype of the last incarnation of the board.

This one is "stuffed" for the CP-65 version.

It was nice for what it did...though most theatres don't fool with multiple digital players anymore.

Steve

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"Old projectionists never die, they just changeover!"

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I already had one of the cards you suggested and have ordered the other today, its only a few pounds so not an issue. Its a pity that your MDI-6555 card is not available as it sounds exactly what I need.

However, I still have one further option which would be to put the DTS 6D back into an SR only screen, where it was originally, and use a DTS 6 with the CP55. The advantage is that the DTS 6 is wired in between the DA20 and the CP55, unlike the DTS 6D which is wired into the DA20. When it has vaild DTS the DA20 is cut out and when there is no vaild DTS or the DTS 6 is turned off the DA20 is allowed to pass thru.

This method would be the easiest of all!! The only additional wiring would be to control the DA20 format switching thru a relay controlled by the DTS 6 so that the DA20 cannot force a reversion to SR while there is valid DTS. While the DTS is valid the DA20 can do what it likes, it may think it is reverting but in reality the formats won't have changed at all. If DTS does revert the control line would be restored along with the format switching for the DA20.

Clearly the DTS 6 was designed with multiple digital formats installed, as you say there is a tendancy not to install multiple digital formats today, which is maybe why the DTS 6D had this design change. Also more modern processors can cope with more than one 6 channel input. It could also be a cost issue as I'm sure it must be cheaper without the additional switching required.

Either way the DTS 6 seems the more attractive, easier solution..... unless anyone knows differently?

Choices, choices.... what am I to do

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just to let you know how things are going...

I've used the relay card from DTS, thanks for the suggestion Steve, as a switching interface between the DTS 6D and the DA20. 5v switching is supplied by the DTS 6D so when there is valid DTS the interface switches out the DA20 and the DTS 6D into the CP55.

Brad, I've also passed the sub signal thru the switching so all channels are switched as required.

Basically it works like this....
If there is no valid DTS then the interface remains off and the DA20 is passed to the CP55. Valid DTS and the interface is switched on and the DTS is passed thru to the CP55.

Two other things had to be considered. Firstly, as SRD is in fact running in the background it could revert to SR, thus switching out the DTS. So an interface relay has to be included that switches out the DA20 format selection to the CP55 while DTS is playing so reversion of the DA20 in the backgound simply does not happen.

Also 'IF' the DA20 has reverted to SR, and the DTS itself then reverted the current format would still be format 10 (Digital) on the CP55 so NO SOUND! Therefore the DTS6D must revert to format 10 (DIGITAL) NOT as you would expect SR. As format 10 is selected it will automatically revert to SR if required or stay in SRD if all is well.

As we are still 'On Screen' with the shutter open when valid DTS returns the interface will switch back in and a format 10 selection is made.

Finally, I personally don't like the way DTS switch to Non-Sync at the end of the show and GRAB sound when there is valid DTS. So I always install an inteface with the projector shutter so that the DTS can only select formats 'IF' the projector shutter is open, ie 'On Screen'.

It all runs like this....

Show running with NO DTS, automation pulses Format 10 (Digital) SRD plays or reverts to SR as required.

Valid DTS starts and interface switches out DA20 and DTS In and format 10 (Digital) is selected, DA20 format selection is disabled by interface.

(DA20 is happily running to itself in the background, and may revert but does not actually do anything)

DTS reverts due to damage.... Interface switches off and passes DA20 to processor, at the same time the DA20 format selection is enabled again and format 10 (Digital) is pulsed just in case SRD has reverted, if so DA20 will then revert to SR.

Valid DTS is restored and the interface switches DA20 out and DTS in, also format 10 (Digital) is again selected.

At the end of the show the automation will fade sound out, select Non-sync, and fade sound back in. DTS format selection is disabled as the projector shutter closes so the DTS cannot make any further format selections.

I've had it all running today and whilst very untidy it all worked a dream..... it needs more testing and lots of simulated reversions just to be sure, but so far so good.

Finally I'll make sure it all tidy and mounted in a metal box for additional screening.

Thanks for everyones suggestions.

Regards Ken

Had it all running perfectly this morning. Did dozens of single and double reversions and it worked a treat.

One thing I did forget was that the automation pulse from the DTS 6D should always pulse format 10 (Digital) so a link between SR AND DTS on the back of the DTS 6D needs to be made.

This way when there is valid DTS it pulses format 10 and when it reverts it pulses format 10, as the interface relays drop out and pass the DA20 into the CP55.

Reversions from DTS to SRD are instant, as are reversions from SRD to SR. It is noticable when a double reversion is done, DTS to SR, however as this is only ever going to happen if a print is very badly damaged so its not a problem.

Hope this is of interest to you all.

quote:

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It is noticable when a double reversion is done, DTS to SR, however as this is only ever going to happen if a print is very badly damaged so its not a problem.

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...or if a film has a DTS soundtrack but no SR-D. Universal released a fair few of these in the mid-late 90s (Jurassic Park 2 and the restored Vertigo spring to mind) and I'd get the odd French or Bollywood film which was DTS only, but I'm sure there aren't enough of them for this to be a major issue.

Very funny comeback Ken, I laughed myself off my chair when I read that. I like a person with a sense of humour. BTW didn't you play Jodie Foster's dad in Contact?

The logic switching involved here could be very easily (and efficiently) done using a cheap little microprocessor. Maybe it's worth us making a little outrigger box for this function. But are there enough people out there running both a DTS and a DA20 to make it worth the effort?

Also Steve, I must say your "example" post was very well written. Well done!

I've finished the interface box with everything inside. It's not the tidiest of things but its very solid. I'll mount it inside the rack in the morning and give it a final test.... then its a permanent fixture.

I'll say it one more time ... and I hope we can put it to rest now

As for looking like Jodie Fosters father in Contact, well I may have looked like him at one time but nature has taken her toll, my gut is getting bigger and everythings heading south!! And I've a lot less hair now. Hope Brad won't have me up for misrepresentation with my pic being out of date!! I'm still quite cuddly and hugable

And back to topic...

one of the reasons for not using a ready made logic card from DTS was that I don't like DTS 'Grabbing' the sound when time code starts and switching to Non-Sync when the film finishes. I much prefere to leave the format selection to the automation which does a great job.... we have CE's TA10. The other thing is our processors, CP55 & CP45's, all have fade out & fade in and I found that allowing the DTS to do it's own thing often switched format during the fades. That's why I have the interface with the projector shutter so that the DTS cannot do anything if the shutter is closed. It's very much a personal thing but it's worked fine here for a long time.

The modification for 'Fade In' is unusual and I belive mine are the only one's to have such a mod done to them. In a multi screen situation with films often starting at the same time it allows fully automated presentation that is consistent from one show to the next, something I value more than 'Ultimate' presentation that cannot be guaranteed. We don't have auto len's changing but it does let us leave a show to run if we have to. One of our screens has a clock start as well so it helps there to have full Fade in & Out.

As it stands I can be sure that my shows run exactly the same way with no individual personality f***ing things up behind my back.

This was the reason for trying to get the DTS & DA20 working togeather so that rather than turning the DA20 off when running DTS, and forgetting to turn it back on, I can be sure we run everything in the appropriate format.

However, if you do come up with something that'll do everything I want then let me know

I'm always happy to get my hand's on new gadgets...

Speaking of photos I was thinking of sending Brad a photo of myself from 20 years ago when I was the spitting image of George Clooney (I wish). I get pretty sick of seeing that ugly old guy (whoever he is) over there on the left.

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