Exhibitors Herald and Moving Picture World (Apr-Jun 1930)

56 Better Theatres Section April 12, 1930 MELLAPHONE « O C A EACH TURN TABLES uO\3 sjx Special prices on Amplifiers, Speakers, Refiners, Tubes and other accessories. Write today for full information on Turn Tables and Sound on Film . Excellent possibilities for dealer s9 and attractive sales proposition. — LET YOUR PROJECTOR BE— MELLAPHONE EQUIPPED MELLAPHONE TURN TABLES are truly superior to many selling for much higher prices. This reproducer is guaranteed to give absolute synchonization, quiet vibrationless operation and long life. Adaptable to any type projector and may be used with non-sync equipment. Simply and stoutly constructed. Gleason Gears. New Departure Ball Bearings. Two Balanced Fly Wheels. Leveling Pedestal Screws. Elec. Research Laboratories or Audak Pick Ups. Spring Suspended Mechanical Filter. Improved Type Fader. Record Lamps, Guards and Needle Cups. MELLAPHONE SOUND ON FILM has been painstakingly designed and advanced by engineers specializing in this particular equipment. Mellaphone Sound on Film has been manufactured since the advent of sound film. Practical installations have been experimented with, rebuilt and redesigned until this equipment reached the high standard of excellence, simplicity, and trouble free performance characteristic! of Mellaphone Products. G. M. Photo Electric Cells. All Aluminum Filmheads, uses no chains. Latest Samson Head Amplifiers. Real Synchronous. !4 H.P. Motor. Finest Optical System Obtainable, Gleason Gears. We now, unreservedly, recommend Mellaphone Sound on Film for immediate installation. MELLAPHONE CORPORATION SBEB? acoustic analyses may be laid to inaccuracies in data submitted when gathered by individuals not fully conversant with acoustic problems. The standard survey form employed covers six printed sheets, to which may be appended considerable additional data in unusual cases. In addition, architects’ drawings are secured, where practicable, and checked with conditions as they exist in the theatre. Where such drawings cannot be secured, very accurate scaled sketches must be made, the theatre being carefully measured for this purpose. This data is then forwarded to the engineering department, where a group of 16 engineers with the necessary clerical assistance, translates this data into the facts necessary for determining the existing acoustic condition. The formula of Sabine mentioned above serves as a useful approximation of conditions. This, however, is modified by many factors developed by intensive experimental work and proven in the analyses of over two thousand theatres. The value of absorption to be assigned to items in a theatre must be modified with respect to its location in the theatre, as to amount and kind of sound that will reach it. Computations, based upon a large series of measurements, may be made indicating the loudness of sounds that will be produced at different points throughout the auditorium. The plans are analyzed for the existence of sur faces which may cause echoes, or may so concentrate sound as to produce interferences or other undesirable conditions. These facts showing the present condition, are carefully reviewed by an engineer and the necessary measures to be taken are determined. Most of the problems may be solved by locating, at the correct points, materials that have the proper amount of sound absorption and will absorb sound at different pitches in the correct degree. Means are then considered, where required, of securing a distribution of sound that will have satisfactory uniformity throughout the auditorium. The reverberation is adjusted not merely to satisfy conditions for intelligible speech, but to be just the right amount to give a natural sound to the voice and a pleasing quality to music. Theatres may be built in a fashion best to distribute sound. However, it is difficult to create this situation in existing theatres, except where there is available a sound projector that has directional characteristics, which means that sound may be distributed throughout the auditorium as circumstances require. From a list of approximately one hundred different types of commercial materials, all the characteristics of which have been obtained and recorded, it is possible to select several materials which will best serve to produce the ideal conditions required. Of these materials which are suitable acoustically, one or more that would satisfy the other requirements, such as suitability to the existing architecture, general appearance, compliance with existing ordinances governing fire protection, and cost are considered. From all of the above facts a recommendation is prepared, by following which correct acoustic condition may be obtained in the theatre. These recommendations point out the existing defects, such as excessive reverberation, possibility of echoes, existence of serious sound concentration, interference, architectural defects in shape or proportion, arrangement of balconies, etc., which may have detrimental effect on sound reproduction. The surfaces which must be treated to correct echoes and concentrations are indicated, as well as the surfaces best adapted for the location of corrective material to improve reverberation conditions. Where sound distribution does not appear to be adequate due to unusual architectural conditions, recommendations may be made for special arrangement of projectors to overcome these conditions. The acoustic materials that appear best suited for use in the theatre are suggested, allowing full latitude to the exhibitor in selection of materials from the standpoints of appearance and econ-| omy. While the materials suggested are considered well suited, there may be others that the exhibitor prefers to use.