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This topic comprises 2 pages: 1 2
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Author
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Topic: CP 45 preamp out and Perspecta Sound
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Frank Angel
Film God
Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999
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posted 09-28-2002 02:03 PM
Hi Bernie, I almost got to see that FORBIDDEN PLANET presentation. I also ran it but when I did, I didn't have enough time to go hunting for a PS integrator. I think Dolby actually made one at one time that was a simple CAT card plug-in card....or so I was told. I also ran NORTH BY NORTHWEST that was supposed to have Perspecta with no chance to try to get it to work. So what you are saying is that that PS integrator needs a solar cell level signal IN, but you need it AFTER change-over, right? How bout if you can grab a signal out of the CP45 anyplace after the change-over, even if it is already preamped to line level, no reason why you can't just put a 20db attenuation pad on it and drop it down to solar cell level or whatever the integrator likes to see at its input. Test points should be fine, especially if you are throwing a 33k resistor between it and the PS integrator input -- the CP45 won't even know the load is there. I sure want to catch a show at the Jersey one of these days. For anyone who is within walking, riding, swimming or flying distance of this theatre and the restoration project that these guys have been working on for years, this is a MUST see. The theatre is a beauty to behold in and of itself, but more importantly, Bernie and Bob Furmanek and the rest of the crew are our kind of people. Frank
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Dick Prather
Master Film Handler
Posts: 259
From: Portland, OR, USA
Registered: Feb 2002
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posted 09-28-2002 03:37 PM
Bernie, Good luck on your Perspecta project. Even though not true stereo it still sounds good. I have noticed lots of the restruck prints also have had the sound remixed and the trigger tones not put on. Seven Brides for Seven Brothers had perspecta on the leaders but no tones when a same reprint Gigi did. My first unit was a Fairchild and I did replace all the caps and changed a voltage divider to increase the trigger voltage for channel switching. I still had a slight bleed over from the 40 Hz The intergrater imput can be hooked up four ways. Your manual should give you the options. You can go 600 ohms with 0 dbm, 100,000 ohms to bridge at -40 dbm adjustable, 600 ohms circuit at -40 dbm adjustable, or 600, 250, 50 ohms at -60 dbm adjustable. One of these option should work fine for you. Also be sure to watch your projector speed. That is important for the tight band pass filters.Frank, I knew a guy in LA that made a solid state one but he would never sell or give out any info on it. It used the Cat 150 slot A few years later I found one from Dion Hanson at Cineman in the UK. Pluggs into the Cat 150 slot also and works great. I have had no problems with it at all. Dick
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Stephen Furley
Film God
Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002
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posted 09-28-2002 05:48 PM
Hi Bernie,I can't help you with the CP-45, I've never even seen one of them yet. Are you aiming to acquire the worlds entire remaining stock of integrators, and put them back into use! I hope all goes well with the show at the Loew's this weekend, North by Northwest should look good on that screen, sorry I can't be there to see it. When I was at the theatre in April, you had a switch, not in use, but in one of the rooms off the projection box, labeled something like 'mono', 'magnetic' and 'Perspecta'. Have you kept it? I rather hope that at least one of them will be preserved, even if not in use, as it is described in the original Perspecta documents in the Widescreen Museum, and is thus of historical interest, as part of the original installation. I still have some booklets and other things, I will have to get them over to you sometime. I would like to come to another show at the Loew's, but getting time off work, booking flights, hotel etc. takes time, so I was not able to do it for this weekend. The Sci. Fi. weekend was advertised several months in advance, so I was able to arrange everything, including getting a Passport, but this weekends show was only anounced a week or two ago, at least as far as the e-mail list and web site are concerned. Would it be possible for future events to be anounced further ahead? Are the Brenographs still in the condition they were when I saw them? If so, could I have a go at giving one of them a clean-up etc., next time I am there? I hope you are still using carbons, knowing how much the things cost now, and hearing about the reported difficulty in obtaining good ones, the future doesn't look bright. (Pardon the pun.) The four track mag penthouse I acquired over there, along with another, similar one, and a Dolby MPU-1 is now installed in the private cinema of someone living in the English Lake District. I had difficulty finfing a Cat.93 12kHz. switch card, but managed to get one from Boston Light & Sound. Projectors also converted back to carbon. Picture and sound both very good. Hope to see you again soon. Dick, I also have one of the cards from 'Cineman', and can confirm that it seems to work well. While very different in design to the original units, it seems to be functionally pretty close. For those who haven't seen these cards, they are the same size as the Cat. 150, which they replace. They are all analogue, and have about eight ics and a large number of caps, resistors and diodes. Are components are mounted through the card, there is no surface mount technology used, so the card could be easily repaired or modified, if needed. One additional feature which the card has is the ability to send the sound to the surround output, as well as L,C and R, when all three tones are present. This feature can be enabled by moving a jumper, but I haven't tried it. One of the original Perspecta documents claimed that it was intended to introduce a surround channel, with a 25Hz. control tone. I have found no evedence that this was ever implemented. I would be intrerested to know if the gentleman I met at the Loew's who had worked with Robert Fine on Perspecta, I'm sorry, I can't remember his name, can shed any light on this. The 'Cineman' card is all hand soldered (a lot of work), but the card itself is very professionally made, no rough, hand-cut corners etc. When I bought my card earlier this year, they cost 300 pounds, not cheap, but not not unreasonable, considering the amount of work involved, and the very small quantities produced. I am very glad to see some of the original integrators put back into use, but I think there is a place for the modern cards as well, for one thing, there are much easier to take to a theatre for a one-off show, they can be carried in a coat pocket, and installed in a minute or so. The only problem with them is that they can only be used in a processor which takes a Cat.150. The CP-50, 55, 65 and 200 are all fine, but not the 500 or 650. I'm not sure about the 45 or 100. It is my ambition to have a 200 with all the 'extras' some day.
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Bernie Anderson Jr
Master Film Handler
Posts: 435
From: Woodbridge, New Jersey
Registered: Apr 2000
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posted 09-28-2002 10:27 PM
Wow! I didn't think this post would get this much response. Anyway, for more info on Perspecta check out the Widescreen Museum at www.widescreenmuseum.com Go under Soundformats and it's listed as 1954 Perspecta Sound Articles. Well, as an update. The Perspecta is in and works to some degree. Need a little more fine tunning. If anyone ever does this again with a CP 45 this is what you need to do. Using the Test points on the inside of the CP45 (L-R-Comm) Connect the L and R together as one. Now connect the two wires to the input on the Perspecta. Remember to make sure that your hot wire is to the left terminal. It won't work the other way, which I found out. Then connect the out put of the Perspecta (LCR) to the Aux/Non Sync 2 input to the CP45 and then press AUX/NS2 on the front panel. And the damn thing finally works. Well to a certain degree. It seems that it's not panning properly. And what I think it is might have something to do with the CP45. When I got it, we had to remove, either a cap or a resistor to get rid of the center mono. It was originally set up in the theatre as Center mono, split surrounds. I'm not sure if there is something for the Aux imputs too, but more to follow. A note of the Dolby card for Perspecta. They never really got it right. Not only does the Perspecta pan the sound to LCR but it also controls the gain and also filters out the cue tones that you might hear on a normal play back . It's like a little rumble in the bass. TheDolby card never allowed for the gain and never filtered out the cue noise, although it did pan properly. But if you come across one for a dolby unit, I would pick one up for the hell of it. Remember also, that MGM cartoons from the era are Perspecta too. So I bet some of your Tom and Jerrys are Pespecta encoded. It will say it on the leader in the track if it is. Hi Stephen, The Loew's looks exactly the way it did when you left in April. We had a little fight between the "volunteers" running the place and the film people. So I haven't been back there in months. I'm on to bigger better things at the Rahway, so I hope. Just took over the curator position for the Wurlitzer Theatre Pipe Organ there. Now, this is a place, the next time your here, you must see. Glad to see you got all that stuff back with out a problem. Thanks again guys. Bernie
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Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 09-28-2002 11:25 PM
Perspecta when listened to through a booth monitor isn't very impressive. That is, you'll think it just doesn't do a good job. Downstairs is another thing...they panned dialogue and other nifty tricks rather well, in my opinion. Also, the fidelity on those Perspecta films seemed notably better.I have played with the Cineman "PerSpecTa Card" (a Dolby Cat. 150 sub). I'd recommend it to anyone wanting to play back a perspecta film, including Tom and Jerry shorts. Steve ------------------ "Old projectionists never die, they just changeover!"
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