This is topic Cinemark Policy, digital soundtracks on it in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by David Stambaugh (Member # 1102) on 02-11-2002, 05:51 PM:
This question pertains to Cinemark 17 in Springfield, OR. The current Cinemark policy seems to carry DTS timecode as well as Dolby SR-D (don't know about SDDS). Now being that I am observant about such things 
I've noticed that the DTS version of the policy consistently produces some very strong, deep LFE bass. You can clearly tell the .1 LFE channel is working. But when the policy is played in SR-D auditoriums, that deep bass seems to be missing. This behavior seems consistent in different auditoriums at the same location, depending on whether they are DTS or SR-D (they are all either one or the other; none have both). The features also seem to have much better LFE in the DTS houses than in the SR-D ones. Disregarding the subjective assessment of the LFE sound in the features (which change with every visit), the policy is the same every time and it seems like it should sound about the same in both formats. ?? Any ideas?------------------
- dave
I want that North American cable deal!
Posted by Joe Redifer (Member # 3) on 02-11-2002, 06:45 PM:
Maybe someone played with the subwoofer levels in the DTS houses or lowered them in the Dolby houses.
Posted by Bobby Henderson (Member # 840) on 02-11-2002, 06:46 PM:
The more enhanced bass in the DTS version could be coming from how DTS redirects sub bass info in the surround channels to the subwoofer (actually, this is where the LFE audio is stored, which really makes theatrical DTS a 5.0 format). Most movie theaters have surround array speakers of limited dynamic range. Most sub bass recorded into the surround channels will not be heard unless a crossover filter redirects the audio. Bass management in home theater uses this principal. Dolby Digital and SDDS have full range surround channels and the LFE channel is discrete. Perhaps Cinemark only mixed the audio in 5.0 with it tuned for DTS instead of making a full 5.1 mix.Previous 70mm formats like Format 43 used the method to literally stick two potential mixdowns on the same 6-track mix. Format 43 70mm prints all held backward compatible Format 42 mixes. The mono surround channel in Format 42 also held the sub-bass audio for Format 43. The two stereo surround channels in Format 43 held low bass audio for the two LFE channels in Format 42. The three front stage channels remained unchanged.
Posted by Brad Miller (Member # 2) on 02-11-2002, 06:57 PM:
It could also be the tech who installed the place. For some reason many techs seem to think the dts units are a direct plug in like a DA20 and frequently the pots are not exactly balanced or they fail to set the "digital subwoofer" input properly. Also, depending on the way the dts was wired in, the subwoofer could be running at a fixed level, although I doubt it since this sounds like a fairly recent complex.I can assure you though if the two formats were both balanced identically that the levels would be the same. Sounds like a bad sound tech or a tinkerer in the booth.
Also, can anyone from Cinemark deny or confirm if the dts audio is actually on the dts discs? I know UA made a policy trailer but the audio was never on any disc. You could be hearing analog.
MOVING TO FILM HANDLER'S FORUM
Posted by David Stambaugh (Member # 1102) on 02-11-2002, 07:33 PM:
Brad, sorry for posting on the wrong forum. I wasn't sure if this particular question coming from an inquisitive amateur warranted being on film handler's forum or not. I'm wary of stepping over some imaginary boundary line (which may only exist in my head) on technical questions. 
I also should have stated at the beginning that I'm *assuming* the Cinemark policy soundtrack is present on most/many DTS discs but I don't know that for a fact. In these theaters, anything that plays in analog (especially in the DTS houses) sounds very inferior compared to digital. It's VERY apparent when, for example, they don't have a DTS trailers disc but the feature switches to DTS. At a couple of recent shows I saw there, all the trailers including the policy sounded digital, and the DTS snipe ran before the feature, in digital.
It took me a long time to realize that it's always the Dolby shows that are lacking the deep bass. But that does seem to be the case. I know there's no technical reason SR-D should be inferior in the LFE area. As far as how the policy sounds vs. the movie, it's tough to assess the LFE by listening to a different movie every time. Subjectively it sounds like the Dolby systems consistently lack deep bass, and the DTS systems do not. The only "apples to apples" comparison I can make is with the policy, and even that may not be mixed the same in both formats as Bobby stated.
Posted by Gordon McLeod (Member # 33) on 02-11-2002, 09:45 PM:
Typically DTS sounds bassyer because of the filter on the surrounds tend to let a bit of the sub into the surround channel
Other than that they should be identical if both units are calibrated properly
Posted by David Stambaugh (Member # 1102) on 02-11-2002, 09:57 PM:
The difference I'm hearing is like night and day. There's a section in the policy where in DTS you can hear a bass note that starts around maybe 50HZ and the freq drops continuously to something very low, REAL low. In their Dolby auditoriums, this sound is completely absent. I don't know what the crossover freq is where the LFE takes over, but it sounds like there's nothing there below the crossover freq.------------------
- dave
Look at this! His chin strap has been cut!
Posted by Brad Miller (Member # 2) on 02-11-2002, 10:48 PM:
You know, come to think of it the Cinemark 17 on Webb Chapel in Dallas is exactly the same way. All of their SRD houses are harsh and shrill with not an ounce of bass and their dts houses sounded somewhat ok. I wonder if it was the same tech that set up these theaters. Anyone know?
Posted by Mark Huff (Member # 480) on 02-11-2002, 11:53 PM:
I no longer work for Cinemark, but when I left the image trailer was not on the DTS disk. To answer Brads question of techs. I belive that the techs are different for Oregon and Texas. I think Texas is handled by Sam Wells.Randy can you tell us?
Posted by David Stambaugh (Member # 1102) on 02-12-2002, 12:01 AM:
They have a tech based out of Springfield who takes care of all the Cinemark locations in Oregon (there's only, what, 4 of them, and 2 locations with total of 29 screens are right here in Spfld). Name is Roger I think. Don't know if he would have had anything to do with the original install though.So here's a dumb question. Is there a quick easy way for a tech to test the LFE channel (or any channel) to see if it works? I mean is there a built in test tone in the cinema processor unit, or a special CD or test film loop? (I know, I should go look this up).
Posted by Brad Miller (Member # 2) on 02-12-2002, 12:25 AM:
Yes, there are ways. Older Dolby processors have a pink noise generator card that can be inserted to send pink noise into the desired channel, as do most processors. Some of the newer processors have the pink noise generator built in. Dts has setup discs that the theater may or may not have that could be played to verify if the sub works or not. However to answer the question "is it working", it would be easier to just load up some action trailer and turn off all of the amplifiers except the one(s) driving the subwoofer channel and listen. This of course does nothing for you except to verify it is working. It could be running "too low" under the appropriate setting, or it is also possible that the theater has 2 subwoofers and one of them is out of phase, effectively cancelling out the signal. I see this all too often.
Posted by David Stambaugh (Member # 1102) on 02-12-2002, 12:31 AM:
I guess what I'm fishing for is what (if anything) I could say to motivate them to look into this. Right now I have some decent credibility with them on presentation issues and they seem receptive to input. But I don't want to come off like a know-it-all (might be too late to worry about that) or jerk people around.
Posted by Jim Ziegler (Member # 86) on 02-12-2002, 03:49 AM:
Our image trailers (the few we have left), generally play in digital. I don't know if the trailer is on the print disks or the trailer disks though.
Posted by Paul Konen (Member # 41) on 02-12-2002, 10:23 AM:
When the policy first came out, I think it was on the trailer disk.Now, I think it is on the feature disk althought it has been a while since I have watched the player during policy playback.
Paul.