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Author Topic: RCA Photophone Laser Conversion Paul Trimboli Master Film Handler Posts: 274 From: Perth Western Australia Registered: Dec 2002 posted 01-14-2003 08:13 AM                     I will hopefully be getting an RCA Photophone soundhead and would like to fit Stereo sound as well as a RED laser in place of the exciter lamp. What problems will I face? I plan on installing this into a theatre so am going to make it professional! If I install stereo cells, how can I test to see if I have them set propoerly? Where can I obtain stereo cells? Can I just cut some solar cells down to size? Do I need to install a slit lens, or take it out and just use the laser with it lens and focus system? How many Watts should the laser be? I was think of using lasers off this site http://www.oatleyelectronics.com/lasers.html Probably the 10mw module I was thinking. What kind of power supply would I need? What kind of adjustments should I make avalible or either the Laser or stereo cell mounts? What test equipment will I need to test it? I know some will say it is not possible, it has to be possible! Thanks for any help you can offer me.  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 01-14-2003 10:19 AM                        You don't need the LED reverse-scan modification if you just want stereo. Kelmar sells the brackets and solar cells that you will need. You might want to upgrade the sound optics as well if they are old or damaged. The Dolby manuals spell out the alignment procedure quite nicely, though it would probably cost you more to buy the test films and oscilloscope (if you don't already have them) than it would to hire an experienced tech to do it for you.  |  IP: Logged Ken Layton Phenomenal Film Handler Posts: 1452 From: Olympia, Wash. USA Registered: Sep 1999 posted 01-14-2003 11:17 AM                     Kelmar Systems makes the solar cells & mounts for many makes/models of soundheads. Visit their website of www.kelmarsystems.com see the section called "transducers" (linear is mono, bi-lateral is stereo). They also make LED reverse scan kits. It would be helpful to have the model number of your soundhead handy. Component Engineering (www.componentengineering.com) makes an excellent lower cost reverse scan LED kit for the old RCA 1040 and 1050 soundheads that don't require you to carve up the soundhead castings in order to fit it. Both companies would be glad to provide you with the names of their Australian dealers. Also look in your telephone directory under "Theaterical Equipment & Supplies" for other dealers.  |  IP: Logged Paul Trimboli Master Film Handler Posts: 274 From: Perth Western Australia Registered: Dec 2002 posted 01-15-2003 12:16 AM                     I would like to convert it from not only Mono to stereo but to a RED laser light source, but I want to do it as cheap as possible becuase buying something like a JAXLIGHT is going to cost me more then my soundhead and projector is going to cost me! I am hopefully going to get an RCA Photophone soundhead and a Super Simplex head which I am going to rebuild as well as paint to bring them back to perfect working order to put into a cinema. Any help with the laser? Does anyone have any cells they have ripped out of their projector for a reverse scan system they do not need?  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 01-15-2003 01:53 AM                        Scott writes: quote: You don't need the LED reverse-scan modification if you just want stereo. He will if cyan soundtracks are introduced industry-wide. Personally I think this is unlikely now, because we are so close to a possible big scale conversion to that going over to cyan prints no longer makes economic sense.  |  IP: Logged Paul Trimboli Master Film Handler Posts: 274 From: Perth Western Australia Registered: Dec 2002 posted 01-15-2003 08:49 PM                     I was talking to a projectionist in Austrlia who said digital cinema has a long way to go, so I do not agree that it will be taking over soon. Is there much point in my worrying for the time being about a red light source? So I just convert it to stereo and leave it at that? Any advantages to red light in normal B & W soundtracks? Is it possible to just buy the stereo cells with a mount to put inside my mono soundhead?  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 01-15-2003 09:23 PM                    There is a great advantage to reverse scan over a conventional pickup. Currently this is done with red LED's (these are not lasers, BTW). Originally the modern reverse scanners used IR LED's. (Modern because reverse scan was a technique used previously. Specifically it means that the soundtrack is illuminated and an image of it is focused on a slit in front of the pickup element as opposed to focusing a slit onto the track.) The advantages are better frequency response (you can considerably reduce the pre-amp HF gain when going from conventional to reverse scan) and much better channel separation (crosstalk reduced to nil). Given the costs involved and presuming you have other needs I would just fit it with a stereo solar cell and worry about reverse scan later on. Remember that if you are going all out eventually that leads you to digital sound and your entire analog A chain becomes nothing more than a backup unless you primarily run non digital films.  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 01-16-2003 02:37 AM                        In truth I don't think anyone can accurately predict the timescale for the mass-introduction of digital cinema. I just get a sense that the mass-rollout of cyan prints has been quietly abandoned, possibly because of exhibitor resistence or because the labs don't want to invest in upgrading their production lines. If digital cinema is in any way imminent, this could be a possible factor behind that decision.  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 01-16-2003 06:27 PM                    AFAIK it does not take any investment on the part of the lab, just a different filter pack on the light source of the sound printing head and abandoning the application gear on the processing machine. They would need to run some tests to determine the optimum exposure but that's about it. I'm sure they would gladly do this at the drop of a hat given the order as it will save them money.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 01-16-2003 08:12 PM                     ACL makes an exclent laser scanner for the RCA type scanners http://www.audio-cine.ch/index-en.html  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 01-17-2003 02:12 PM                        Here is what labs need to do to produce compatible "high magenta" dye+silver prints, and eventually cyan dye tracks without silver: http://www.kodak.com/US/en/motion/support/sstLabGuide.shtml http://www.kodak.com/US/en/motion/support/dyetrack.shtml At this week's ITEA and Inter-Society meeting in Los Angeles, Ioan Allen of Dolby reported that it's likely conversion to cyan dye tracks will happen this autumn (September 2003), after at least 80% of screens meet NATO's recommendation of a July 2003 conversion to red LED readers. A majority of screens already have red LED readers, with over 80,000 red LED modules having been sold worldwide. Ioan reported that over 5000 red LED modules have been sold by Dolby since September 2002.  |  IP: Logged Peter Hall Master Film Handler Posts: 314 From: London, UK Registered: Dec 2000 posted 01-19-2003 05:43 AM                        HI - Are you looking at going through or replacing the slit lens ? We have a range of laser units that replace the lens with a line generating laser with a special lens and vernier width adjustment. Sleeves are available for most projectors - I think the RCA uses the same lens as the Century .. Advantages of these are full cyan compatibility plus the same xtalk and hf response of a reverse scan LED reader, plus the lasers last "forever". Have a look at www.fproj.com/cyan for details  |  IP: Logged Sam Hunter Jedi Master Film Handler Posts: 779 From: West Monroe, LA, USA Registered: Jan 2002 posted 01-19-2003 09:36 AM                     Peter that link is dead for me.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-19-2003 09:42 AM                     Peter, I've used Laser kits before and I agree that the laser's have a longer life, however you still have that damed solor cell hanging there. Can't tell you haow many service trips I've made for those things comming out of alignment, or being chipped by a passing piece of film that is bent over.....I much prefer the reverse scan units over anything else. They're easy to install, and super reliable. Can't remember EVER making a service call on one after it was installed. I have replaced a number of red LED's though, but not a really large number. Most of those led replacements have been in digital sound heads too. Switching the red led's on ond off really saves them big time. Mark @ CLACO www.clacoequipment.com  |  IP: Logged Paul Trimboli Master Film Handler Posts: 274 From: Perth Western Australia Registered: Dec 2002 posted 01-20-2003 06:39 AM                     I know reverse scan is good, but the cost is too high. If this goes into a cinema it will not be there long as it will be upgraded within a couple of years of service, so providing the sound is good then that is all that matters. The cinema I work at has just installed a reverse scan reader and has had problems, a show was cancled today becuase it died, not sure what the service guy did to fix it, went home ! So all I want is stereo and a red light source!  |  IP: Logged

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