The Exhibitor (1953)

Stereophonic Sound An Accurate Description of What Multiple Channel Sound Systems Mean to Exhibitors By E. O. Wilschke Operating Manager, Altec Service Corp. “3-D”, “Third Dimension”, “CinemaScope”, “Natural Vision”, etc., are now industry-wide expressions. However, the term “Stereophonic” is given only second¬ ary consideration. The word “Stereophonic” has not yet found its way into the dictionary although the words “Stereo” and “Phonic” do appear and the combination of both deliver “multiple image sound”. Stereophonic or multiple channel sound produces a realism of naturalness far exceeding any illusion created visually. Most exhibitors have seen third dimen¬ sion presentations and a number have seen wide-screen presentations. Few, however, have had opportunity to hear real stereo¬ phonic sound because only a few pictures have been released with multiple track recording, and even some of these were not real stereophonic recording, but were processed. Those industryites who were addition to existing theatre sound system. privileged to witness tests of product with real stereophonic treatment have been most enthusiastically impressed with the dramatic impact it creates. Less than fifty theatres in the country have been equipped to date to present full stereo¬ phonic sound but in every case so far the public acclaim has been lavish. Stereophonic sound is not new. It was first demonstrated in 1932 by Dr. Harvey Fletcher of the Bell Telephone Labora¬ tories. The demonstration was held between Constitution Hall in Washington, D. C., where the Philadelphia Orchestra, under the baton of Leopold Stokowski, was performing, and an audience located in the Academy of Music in Philadelphia which received the concert as a stereo¬ phonic presentation. The naturalness and realism presented to the Philadelphia audi¬ ence clearly demonstrated the value of stereophonic sound which was carried over three telephone channels terminating in three amplifier and loudspeaking sys¬ tems located on the stage of the Academy of Music. The system as demonstrated in 1932 was then made available to the motion picture industry for full stereophonic recording. It appears that this important achieve¬ ment is now to be a part of the motion picture industry. Fortunately for the in PHYSICAL THEATRE Vol. 8, No. 6 May 27, 1953 A behind-the-screen view of the Mastbaum, in Philadelphia, showing the three loud speakers in the proper position for stereophonic sound. dustry the techniques and equipment for stereophonic recording and presentation are realities. The systems are not as com¬ plicated as one would be led to believe. Multiple channel sound reproduction is merely more of the same thing that we now have. All theatres at present are equipped with single channel reproduc¬ tion. Whether stereophonic is to be pre¬ sented three channel, or whether addi¬ tional channels are to be added for control tracks or effects, it is only necessary to add pick-up, amplifier, and loudspeaker equipment. The present stereophonic systems being used consist of three chan¬ nels to reproduce three magnetic tracks recorded on a separate 35mm. film which is reproduced on a three-track magnetic reproducer. Each channel consists of an amplifier system which supplies a loud¬ speaker system; one located at the left, one at the center and one at the righthand side of the screen. In addition, a fourth channel (the present house system) is being employed to reproduce an optical track which is recorded as part of the picture film. This channel feeds a number of auditorium speakers located in the sides and rear of the theatre for sounds and effects. CinemaScope has recently announced that in their system four magnetic tracks will be recorded on the picture film. Under those circumstances a separate magnetic reproducer as such would not be em¬ ployed, but a magnetic attachment would be installed on the present motion picture projector in order to reproduce the four magnetic tracks. The main point to consider in contem¬ plating the installation of stereophonic equipment is that high quality reproduc¬ tion is possible only with high quality equipment. The main stereophonic chan¬ nels must be identical in all respects. The pick-up, pre-amplifier, main amplifier, and loudspeaker systems for the three channels must be identical, not merely similar. Unsatisfactory results, will be obtained if attempts are made to provide multiple channel equipment with dissim¬ ilar equipment. Furthermore, adequate power in the amplifier systems should be provided to drive high quality speakers at full efficiency. It is obvious that the manufacturers will not be able to supply equipment for all of the theatres at the same time. On the other hand it is equally obvious that ( Continued on page PT14) The reproducer in this case is a Century head adapted to handle three magnetic sound tracks. May 27, 1953 PT-4 PHYSICAL THEATRE DEPARTMENT of EXHIBITOR