A Direct Positive System of Sound Recording

One of the fundamental advantages of the variable-area system is that the original negative may be reproduced directly without appreciable wave-shape distortion. One printer operation can be eliminated and the film noise considerably reduced by originally recording a track in which the transparent area diminishes as the recorded level is decreased. A direct positive recording system has been so designed that the recording and noise-reduction light-beams are separated in the direction of the film motion. This allows the noise-reduction system completely to anticipate a coming signal, thereby eliminating clipping. When the sound volume is less than is required to fill the track, the noise from the direct recording is reduced further by additionally exposing those portions of the track not needed for the sound-waves. A single shutter vane automatically controls both the transparent area and the additionally exposed area. — A model of the direct positive optical system has been on test in Hollywood for several months. The exposure has proved to be less critical than on the negative-print process. Densities from 0.80 to 1.60 produced only minor quality differences. A good print of a negative compares favorably in quality with a direct positive record, but because of the variations always present in the printing operation, it is believed that a higher average of quality can he maintained from the direct record.

Print ISSN

0097-5834

Published

1939-11

Content type

Original Research

DOI

10.5594/J11917