Motion Picture Herald (Mar-Apr 1945)

What It Takes to Make a Good Theatre Public Address System IMPORTANT THOUGH It IS in the up-to-date theatre's daily scheme of operation, it is surprising how few theatre owners and managers really appreciate just what constitutes a good public address system for the average theatre. I have found that some think a public address installation involves extensive and expensive alterations to their theatre, while others assume that there is nothing to it — just a little matter of picking up an amplifier, a couple of horns and a microphone or two. There are of course, always two ways of doing any job, a poor way and a good way ; but the poor job in most cases can be just as expensive as the good job, in the long run. A public address system which is laid out and installed to fit the specific physical requirements of the auditorium, with equipment expressly designed for theatre use, will give less trouble and better results than a system laid out and installed haphazardly. A public address system should be first what the name implies, a ready and effective means of informing an audience of some special activity" or attraction, controlling patrons in an emergency, etc. — in short, it provides inmediate contact between the audience and management as occasion demands it. The best way to accomplish this is to have in the manager's office a microphone interconnected with the public address system on the stage through Avhich announcements can be made instantly, if need be. Amplifier, horns, microphones, etc., should be purchased from a reliable manufacturer or distributor who will guarantee the workmanship and performance of the equipment. A BASIC P.A. SCHEME Figure 1 shows a typical installation layout plan of a public address system for the average theatre. It gives a good idea of what goes into a system of this kind and how. This particular layout will not fit every theatre exactly of course, for each theatre has its own specific problems, such as structural limitations or obstructions, incorrect acoustic treatment, etc. ; however the general installation layout will not vary except in minor details, or in the equipment makeup, therefore this layout can be used as a basis of discussion, to point out the procedures to be followed, and pitfalls to be avoided. In finding a location for installation of the amplifier, seek one that will be ready accessible, but away from any stage draperies, operating lines, stored scenery, etc. The supporting shelf should be constructed of sturdy iron and be rigidly fastened to the wall. Care should be exercised that the amplifier is not directly under a skylight or window, or in any other spot where there is a possibility of water leakage. A heavy mesh screen should be installed over the amplifier as a protection against the accidental falling of any objects, but it should be removable for maintenance and service work. As an added feature, a sheet steel front can be attached to this protective screen having a hinged metal door with a lock to prevent any tinkering of the amplifier either while it is in use or out of operation. The electric supply to the amplifier should be from a 110-volt 60-cycle, single-phase a.c. source preferably tapped off the panelboard in the manager's office. In this way the manager will .have direct and immediate control of the on-and-off operation of the amplifier. This feeder circuit should be properly fused and have a control switch at the point where it is taken off the panelboard. The circuit wiring should be two No. 12 braided rubbercovered wires run in either J^-inch or 24-inch conduit; and at a point near the amplifier a 20 ampere circuit breaker should be installed. This circuit breaker will give added and instantaneous protection to the amplifier in case CENTURY PROJECTOR CORPORATION 729 SEVENTH AVENUE, NEW YORK 19, N. Y. BETTER THEATRES, APRIL 28, 1945 3!