International projectionist (Oct 1931-Sept 1933)

SOUND PROJECTION FACILITIES IN THE MODERN THEATRE D. M. Cole ELECTRICAL RESEARCH PRODUCTS, INC. Sound and visual projection facilities in the Los Angeles (Calif.), Theatre represent the ultimate in completeness and efficiency. Public address, duplicate picture presentation, broadcast pick-up, and hardof -hearing aids are the highlights of this installation, as described in the accompanying paper which was presented before the Fall, 1931, meeting of the S.M.P.E. by Mr. D. M. Cole of the ERPI staff. THE trend in modern theatre conitruction is toward larger and beter equipped theatres. Mechanical and electrical devices, which enable the exhibitor to furnish better entertainment and more comfort to patrons, are being used increasingly in new theatres, refinements being added as they become available. The Los Angeles Theatre is an example which included in its construction and furnishings all available refinements. The acoustic properties of the theatre were given careful consideration and, hand in hand with good sound equipment, excellent results are being achieved. In addition to the sound picture equipment, various attachments and special features have been provided. The sound facilities include sound picture reproduction, both film and disk, for three projectors; hard-of -hearing aids, non-synchronous attachment, broadcast pick-up, and public address systems. The amplifiers and control panels are mounted on five racks, centralizing" all the panels, with the exception of the public address control equipment, which is located in a room adjacent to the projection room. Sound Equipment Two sets of amplifiers are provided, permitting simultaneous reproduction of two programs: i. e., while sound pictures are being shown in the theatre auditorium, announcements can be made to other parts of the theatre, if required. The duplicate set of amplifiers insures sound in the theatre auditorium at all times. Switches have been used throughout in this installation, with the exception of the inputs connecting the microphones to the mixing panels, where jacks are used. Monitoring facilities for both systems are provided. Loud speakers of various types to fit the particular purpose are installed about the theatre to care for the distribution of programs. The sound picture equipment is of the largest type of Western Electric equipment supplied for the de luxe theatres. The amplifier equipment consists of a voltage amplifier, a medium power amplifier, and two high power amplifiers. The amplifiers, with the exception of the voltage amplifiers, have "built-in" rectifiers and filters which furnish plate supply from alternating current. The plate current of the voltage amplifiers is obtained from the rectifier of the medium power amplifier with which it is associated. The filament supply for the medium and high power amplifiers is obtained from 110-volt A.C. stepped down to the proper voltage. The filament supply for the voltage amplifier is obtained from a motor generator set. Horn control panels are provided for impedance matching and testing of the horn receivers. Pick-up equipment is provided to permit the reproduction of either film or disc records on any one of the three projectors. The equipment is of the universal base type. Three shallow type stage horns, each equipped with two receivers, are used behind the screen for obtaining correct illusion and distribution of sound. A large sound screen, 60 feet by 40 feet, having a good frequency transmission characteristic and good light reflecting qualities, is installed. The volume of sound is normally controlled in the projection room, but an auxiliary fader is available for use in various locations in the auditorium. The auxiliary fader is used for previews and premiere openings where special attention to volume is essential. Duplicate Projection In the Grand Salon a miniature screen is provided which enables patrons to view the picture which is being shown simultaneously in the theatre auditoriiun. The accompanying sound is reproduced by a loud speaker which is located above the screen behind the grille work. Loud speakers are provided in two "cry rooms," enabling those viewing the picture from this point to hear the accompanying sound. Hard-of -hearing aids enable partially deaf patrons to hear both the sound picture reproduction and stage programs. Single receivers, provided with head bands, are employed. A regulating de [23] vice in the cord permits the patron to adjust the volume to suit his need. The cords are equipped with plugs which are plugged in receptacles installed on the arms of the seats. An A.C.-operated amplifier, which obtains a small speech input voltage from one of the system amplifiers, furnishes the power for these receivers and precludes the possibility of short circuits in the hard-of-hearing aid attachment from interfering with the operation of the system with which it is associated. For the reproduction of incidental music recorded at 78 rpm., a reproducer set is installed in the projection room. Two turntables with a fader make possible the running of continuous programs for entrance music, exit music, and sound effects. Radio Broadcasting Two amplifiers are provided to furnish programs over telephone lines to radio broadcasting stations. Programs from any of the microphone pick-up points, including the broadcasting studio, can be transmitted. The amplifiers are all A.C. operated and the necessary impedance matching and isolating transformers are provided. The public address portion of this installation consists of high quality micro{Please turn to page 28) View of the miniature screen which enables patrons to see in the lounge the piclure simultaneously projected in the theatre auditorium