History of Sound Motion Pictures

Our thanks to Tom Fine for finding and scanning the Kellogg paper, which we present here as a " searchable image ". This material is posted here with permission of the SMPTE. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the SMPTE. By choosing to view this document, you agree to all provisions of the copyright laws protecting it. Better Light-Modulating System for Variable Area. Mention was made in the section on loudspeakers of a demonstration by Dimmick and BelaP9 of sound with extended frequency range. Aside from the 'improved loudspeakers and the ribbon microphone (whose response was practically uniform from 60 to 10,000 cycles) there were a number of advances that contributed to the result. The new galvanometer and optical system made so much more light available that it was feasible to reduce the width of the recording beam to 4 mil, thus improving resolution. No small factor in giving clean high frequencies is avoidance of flutter, particularly rapid flutter such as 96 cycles. In the demonstrations, both recording and reproduction were on magnetic-drive machines. * (The rotary stabilizer was not yet available.) Ground-nois: reduction was by gal-vanometer bias with a single narrow line of transparent film when the modulation was zero, and it is my recollection that a measurement indicated a ratio better than 50 d b between signal at full modulation and the ground noise when biased for zero modulation.Type Printers. With the sprocket-type contact printers in almost universal use, a certain amount of slipping of the negative with respect to the print film is almost inevitable. The curvature at the sprocket compensates for a certain negative shrinkage at which the ratio of radii of the shrunk negative and unshrunk print stock is just equal to the ratio of their lengths. The sprocket diameter is designed to make this compensation correct for an average negative shrinkage, but it will be only approximate for negatives whose shrinkage * T h e special film-phonograph used in the demonstrations was a prototype of those used in the Disney Fantasia reproduction (see Fig. 7, p. pulled by the magnetically driven drum over a curved supporting plate where the tracks were scanned, and was steadied at the other end of the plate by another drum with …

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