Journal of the Society of Motion Picture and Television Engineers (1950-1954)

in lacquer-coating the film or the sound stripe? Mr. Schmidt: I rather doubt that any normal lacquer coating over the sound track would be useful in any respect. Magnetic recording depends on intimate head contact for optimum results, and anything that you put on the top of the track will interfere with your head contact. Mr. Carpenter: How much tolerance do you think is allowed? Mr. Schmidt: Zero. Mauro Zambuto (Italian Films Export}: Have any tests been made to 'find out exactly what the performance is of the old-fashioned sprocket-hole film on the new type of sprockets? Dr. Carver: In the very beginning, I believe that Twentieth Century-Fox realized that any new sprockets they made would have to run at least as well on film with standard perforations as the old sprockets. It turns out that if you do not increase the diameter of the sprocket you get slightly worse results, but if you use an intermittent sprocket with a diameter of 0.953 in. you get at least five times as good results as far as wear and tear on the film goes as you would with a 0.935-in. sprocket such as is ordinarily used. You also get better results than if you use a 0.943-in. which is the ASA standard. The 0.953-in. sprocket more than compensates for any decrease in wear you might get with the narrower teeth. Does that answer your question? Mr. Zambuto: Thank you. It does as far as wear and tear are concerned. But what about the stabilization of the film drive? For instance, you don't have any variation in film positioning both as far as sound track and picture are concerned? Dr. Carver: I can't answer on the sound track, but I can see no reason why we should. I think I'll have to ask Mr. Loomis to say if he has noticed any increased weave on the picture with the narrower teeth? I think he has not. H. A. Loomis (Eastman Kodak Co.): We haven't projected any pictures on the wear tests, so we really don't know. B. C. Passman (International Projector Corp.): Mr. Athey has described briefly the effects-switching system used in the GPL system. I wonder if Dr. Frayne or Mr. Phyfe would care to comment on their systems. Mr. Phyfe: We have a suppressor system now in operation in our labs in Gamden and we have it in production as well; we have used the circuit originally suggested by Twentieth Century-Fox and find it very satisfactory. Dr. Frayne: I can state that we had a working breadboard model about two weeks ago and will probably be in production shortly. Incidently, we have been having some debate with Lorin Grignon as to the feasibility of changing over — instead of having the 1 2-kc on at the same time as the signal, to have instead the 12-kc on during the silent period. It just reverses the operation of the circuit. That was still under debate when I left. Mr. Hilliard: I'd like to comment on that last remark from Dr. Frayne. We have had a great many changes back and forth here and the system which we are presently making — that's International Projector and General Precision Laboratory — is operating, I believe satisfactorily with the 12-kc on during the sound effects. It seems undesirable to make a further change unless it's necessary. Edward S. Seeley (Altec Service Corp.): Was it Dr. Frayne's proposal that, although The Robe has been recorded with 12-kc present when effects are to be reproduced, thereafter succeeding pictures should be recorded differently and that the equipment now in use, and there is quite a little of it and it is going in very fast, should al be replaced with equipment that wil work in the opposite direction? Dr. Frayne: It's a very simple change to make in the field. Mr. Athey: Maintaining the 12-kc during the effects sound is certainly, in one sense the hard way to do it. It is my impressior from the demonstration recordings tha we make for Fox that the modulatior noise from the 12-kc, even though th< 12-kc is not audible, is a disturbing factor Unfortunately, and this is just my gues from not very exact results, as the fre quency gets higher, any errors in recording contact become more impressive in thei effect on the signal. What we get if w< do not have perfect contact is a modulate< 12-kc modulation noise. However, ther are great system simplifications mad 234 March 1954 Journal of the SMPTE Vol. 62