|
|
This topic comprises 4 pages: 1 2 3 4
|
|
Author
|
Topic: What goes wrong in digital cinema?
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Carsten Kurz
Film God
Posts: 4340
From: Cologne, NRW, Germany
Registered: Aug 2009
|
posted 09-12-2014 03:54 PM
We had a 'classic' 35mm setup with CP65/DA20, QSC USA amps and JBL speakers.
When we installed our digital system, we ran into trouble when we tried to calibrate the surrounds. It turned out that some of the 10 JBL 8330 we had in a 5 each LS/RS config had their 508G woofers blown. They were essentially dead on low volume signals, but rattled like mad on higher volume signals. We were puzzled because we didn't understand when this happened and for how long this was going on before we did the digital install and noticed it. With the install, we also split them into 3/2 groups for 7.1 to be fed from a 4ch amp.
We couldn't solve the issue with the blown speakers during the installation because we had no spare speakers at hand. We configured a high pass filter on the AP20 for all surround speakers and decided to finish the install. The filter did not let lower frequencies through so the rattle did not occur. It sounded a bit 'phony', but it was a decent workaround.
We then sourced replacement speakers and prepared a check run on all surrounds to identify those with defect woofers. That wasn't as easy as I thought because they were wired in parallel in a wall box and it wasn't easy to get access to all individual speakers with test signals.
Simply listening from the auditorium would not reveal the problem with individual speakers because the adjacent working speakers would mask the missing low frequency at lower levels, and localization was nearly impossible when the rattling occured at higher levels.
We then actually resorted to placing an amp in the auditorium with a long speaker cable and wiring every speaker individually from a ladder with the test signals and listening from close. We were again puzzled to find out that from 10 surround speakers, only three had their woofers still working!
We replaced all those defective woofers, but never learned for how long we were already running with such a mediocre setup. Nobody could remember the rattling to have occured ever during screenings before. Either all those defects occurred during the digital installation due to a wiring or amp error. Or the 35mm DD mixes never carried enough low frequency level to trigger it.
Whatever - we were running this 7.1 setup then for over a year without any issues.
Recently I noticed during a regular maintenance check that all RS speakers were dead. I rewired inputs and outputs of the 4ch amp and it turns out the fourth channel of that amp is dead. At the same time I noticed that one of the LS speakers also was not working (all wired in parallel now). I climbed up the ladder and found the + wire had slipped out of the clamp...
Heck, and again I had no idea for how long this was already going on. Usually during 5.1 presentations, the BSR speakers would back up the missing RS, and one of three/five missing LS/BSL did probably not cause to much irritation anyway .
Harold, if you are looking for a future USL product, a simple way to check/rewire parallel/series wired surround arrays would really help to conduct more frequent equipment checks. We never had issues checking front systems and subwoofer, but these issues with the surrounds really struck me. I am not on-site daily, but often enough to be able to notice that kind of problem early.
Pre-digital, we had two identical issues with our front L/R system's crossover, had to resolder the circuit board to get the HF back.
Other than that, we had a few issues of ordered DCPs arriving, but not their KDMs, and always asked myself what kind of system these distributors operate that allows drives to be ordered, but missing out KDMs for them.
We have reoccurring issues with pre-show content associated with the general use computer this is running from.
We never experienced any DCI/sound equipment failure, never missed a single automation cue (all GPIO wired). A few ingest drives had issues, but we never had lost shows due to that.
We did lose a show due to a bad processing board in our Sony, but it was replaced within one day even though we were not on a support contract.
A lot of CPLs/packages are named badly wrong against DCNC.
Trailers are still mixed too loud, but with playlist based volume control this is no big deal, we play trailers at 4.5 and features at 5.5 to 6.
BluRays and DVDs are still a nightmare to be presented by 'ordinary' staff properly. But I'd say this is a training issue, if we'd do it more often, they would get used to it.
- Carsten
| IP: Logged
|
|
|
|
Buck Wilson
Jedi Master Film Handler
Posts: 894
From: St. Joseph MO, USA
Registered: Sep 2010
|
posted 09-12-2014 04:54 PM
I was appalled when I found they scrapped all our equipment. 8 year old Strong Super Hilite II/Simplex Apogee/Strong AP3 combos. 8 YEARS OLD. 10 setups.
Upon the conversion, I had very painstakingly and meticulously folded up all the platter stands, stacking them very neatly with all the projectors lined up out of the way at the end of the booth. It took me days. I had planned on purchasing at least one full set up at some point in time when they wanted to get rid of them.
They sat there for a year or so, until Regal came along, and one day I came in for my shift and my boss snidely says "Did you get an empty feeling when you went upstairs?" I hadn't been up there yet but knew instantly what he was talking about.
He detailed the crew that came in, literally ripping everything apart; doors off the projectors, rectifiers out, heads off, platter stands apart, throwing everything into a box truck for scrap. There was shards, bolts, washers, etc strewn all about. I was literally heartbroken. WHYYYYY!??! I had threaded that eq daily for 5 years!! I'm still very upset about it. I could've used them at the other theater I worked at too. I would've bought all of them. But instead, they're soda cans now.
| IP: Logged
|
|
|
|
|
|
Joe Elliott
Master Film Handler
Posts: 497
From: Port Orange, Fl USA
Registered: Oct 2006
|
posted 09-12-2014 06:03 PM
I would agree with the lamp installed improperly, or not aligned. I have seen many that they never tightedend down the connectors, and depending on the size of the lamp, it arced and burnt up the connector.
Staff running projectors, even though there are errors, and not reporting them, because they were able to keep it running (overheat errors), until they have nearly fried the projector.
Missing channels on sound - most companies service contracts don't cover sound, and 35mm contracts used too. They have no one to check it anymore, so there is no one reporting it until the center has gone out. I have gone into theaters that have reported sound problems to find that only one channel was working. The rest had blown one by one for various reasons.
Destroyed reflectors, many companies are taking their chances with pushing bulbs beyond their warranties, and I am seeing an increase in reflector replacements. Now I don't know if that's what they report to the bulb companies, as I don't think any of the bulb companies ask for logs, yet . . .
| IP: Logged
|
|
|
|
All times are Central (GMT -6:00)
|
This topic comprises 4 pages: 1 2 3 4
|
Powered by Infopop Corporation
UBB.classicTM
6.3.1.2
The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion
and agrees to release the authors from any and all liability.
|
Home
Printer-friendly view of this topic