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Author Topic: Penthouse digital readers Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 11-18-2007 02:05 PM                     Mark do you have a humidity problem in your booth? Has anyone ever checked the bearings on the penthouse sound drum?  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 11-18-2007 07:05 PM                    Nope, no humidity problems to speak of in any of the three booths (three different theaters). And these units have all done it from pretty much day #1. I do appreciate the comments. But the problem is not that the film bounces. Of course it does. Anything from a splice going through the brain, to static, to the air conditioner blowing on the film hanging between the platter and the projector will make it bounce. When a splice goes through the reader, it will bounce. I expect all of that. Everyone should. The problem is that the really expensive CP650 can't deal with the film bouncing without making the pitch bounce all over the place. Call me crazy, but I find that rather ridiculous. Again, I do appreciate all of the comments, but I really think this ball is in Dolby's court. For now the SDDS sounds great... or at least, better than the 650.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 11-18-2007 07:29 PM                     You need to carefully check the dash pot in the penthouse. I have had to replace numerous ones in CAT 700's and 701's. Also the top lateral guide roller which is the top sprung davis roller... check that for wear on the edge closest to the main frame. If that inner guide edge is silvery (anodize gone) then its shot and should be replaced. Mark  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 11-18-2007 08:08 PM                     Do you have an SDDS reader mounted UNDER the Dolby??? FYI that CREATES such a problem.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 11-18-2007 08:10 PM                       The Airpot is the #1 failure mode on the 701. I'm not sure why, but I believe the piston rod breaks off leaving you with zero damping.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 11-18-2007 09:25 PM                     I haven't had them break yet... they seem to develop what is equivelent to slop but it isn't really... and you can't get the proper damping by re-adjusting the screw at the bottom. I think its uneven wearing of the glass tube itself. The west is VERY dusty and I think the dust causes the odd wear... Mark  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 11-18-2007 09:40 PM                     We have had the rod become effectively disconnected from the piston...we have also had good luck re-cementing them back.  |  IP: Logged John Walsh Film God Posts: 2490 From: Connecticut, USA, Earth, Milky Way Registered: Oct 1999 posted 11-19-2007 07:20 AM                     Same here; the piston disconnected from the rod on several of our readers. They weren't 'swaged' enough, and slipped through the hole in the piston.  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 11-19-2007 09:25 AM                       quote: Sam D. Chavez the piston rod breaks off leaving you with zero damping. Same thing that happens with Christie projectors.  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 11-19-2007 10:36 AM                    I love all of you guys. Really I do, and I mean that with all sincerity. The only reason I can think of that would make you want the speed of the data going into the processor to have anything to do with the pitch of the sound waves coming out of the processor would be to have the pitch of the digital track match perfectly with the pitch of the analog track. If the analog track is running through a projector that's operating at 24.004 fps, then the sound track's pitch will be slightly higher than it should be. It makes sense to have the digital track also pitch slightly higher to match that pitch of the analog in order to mask digital drop outs better. However, wild pitch variations like the ones we're seeing should absolutely not be possible. The 650 should be able to average the speed output of the FIFO buffer a lot better than it is. I assume that there is some sort of a speed averaging algorithm being used on the speed of the FIFO's output. It seems to me that the sample size of the average is way too small, but what do I know? Whether this is a software issue for Dolby to fix, or if it's a problem with all of our processors I don't know. My biggest gripe: If customers are laughing at your presentation, that's a problem. But I guess for others in my world, it's not. Have you ever felt like you're the only person to care about something? Do you remember how tired that makes you feel? I'm very tired right now. Thanks for waking me up. It's been a pleasure, but I think I'll go back to sleep. Wake me up again when this is fixed, please. Frank, I'm sorry this thread drifted way off topic. If anyone is interested, here is a thread where this is all pretty well documented, with videos. Thanks again for all of the tips.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 11-19-2007 11:32 AM                     I would fix the problem with the bounce first then look at the processor one should not use electronics to fix a mechanical issue  |  IP: Logged David Stambaugh Film God Posts: 4021 From: Eugene, Oregon Registered: Jan 2002 posted 11-19-2007 11:44 AM                        This has nothing to do with anything, but last night the local FOX station was having trouble with their network feed, which is obviously digital. The picture was doing the blocky thing you see when there aren't enough bits to make the entire image. But what was really strange is the Dolby Digital audio was doing a severe "wow" thing just like Mark describes. It was speeding up and slowing down, not just dropping out or "skipping".  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 11-19-2007 12:01 PM                    Does the film in your penthouse digital readers not bounce when a splice goes through?  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 11-19-2007 12:15 PM                     Mark, two years ago on that other thread you linked to above I pointed out what happens if you permit that top right spring-loaded roller on the SDDS2000 to be in the film path when using an SRD penthouse. In re-watching that video you submitted, I see that you ARE threading around it. Has that threading still not been changed? If that has not been flipped, this bashing of the Dolby product has no merit because I guarantee you that mounting setup WILL cause exactly the complaint you are describing. Set it up in this manner... Just make sure you mount the SRD a bit forward so that roller isn't touched at all. Ideally though, put the SRD directly on top of the projector and bypass the SDDS via the two 70/35mm rollers. As far as your cue tape, as long as you are using that shitty cue reader, you will never get totally rid of that. (And make sure your loops aren't dragging over themselves when you run tests.) Also in terms of the Dolby guys trying to assist, did you ever swap the readers as was noted on the last page of that other link? They can only give you so much help if you don't give them the troubleshooting assistance. Finally if none of that helps, swap the projector motor with another machine. Gordon is absolutely correct when he says to go after any possible mechanical problems first.  |  IP: Logged Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 11-19-2007 12:44 PM                        Mark, no need to apologize...no matter how it drifts, it's always chock full of information and a learning experience. I got my answers (thanks everyone) somewhere on page 2.  |  IP: Logged

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