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1945 Theatre Catalog, 4th Edition, Page 505 (479)

1945 Theatre Catalog, 4th Edition
1945 Theatre Catalog
1945 Theatre Catalog, 4th Edition, Page 505
Page 505

1945 Theatre Catalog, 4th Edition, Page 505


INSTALLATION OF SPEAKER STANDARDS in relation to parked automobiles is shown in this Radio Corporation of America drawing. The lB-inch high concrete base is pear-shaped and approximately l8 inches wide by 30 inches long, with the blunt and towards the screen. Standards are placed l8 feet apart, providing ample

though the sound equipment was pushed to its maximum capacity. This not only increased the amount of sound escaping from the theatre, but it also over-taxed the equipment. Another disadvantage of the centralized speaker system was that, when the screen was viewed from the rear ramps, the reproduced sound was not synchronized with the action of the screen. The reason for this condition is that sound travels extremely slowly compared with the speed at which light travels approximately 1,4 mile (or1,266 feet) a second compared with 186,300 miles a second-and the light from the screen would reach the last few ramps a fraction of a second sooner than the sound.

Pole-type speakers for drive-in theatres located at least three-quarters of a mile from residential communities, where operators do not wish to install the in-car speakers, provide excellent sound reproduction with greater control and Hexibility than the central speaker system at the screen.

These speakch consist of specially designed directional horns, mounted on poles at least 30 feet in height. and usually placed at intervals of about 100 feet at the sides of the parking area. In most cases eight horns will suffice to handle the sound for theatres up to 600 cars.

These speakers are individually controlled from the projection booth and can be cut out when cars have left the area with no impairment of the sound quality in the other parts of the theatre.

In above-ground type of speaker system, a permanent magnetic speaker unit is usually employed. In this form of



sound distribution system, each unit is intended to serve two adjacent cars.

The units should be mounted in suitable weather-proof housing bafiies, permanently installed on posts placed approximately 19 feet apart and on a line 2 or 3 feet ahead of the car front bumper locations.

The advantages of this type of distribution are essentially confined to the permanency of the installation, the need for fewer attendants as compared to the inecar type of system, and the fact that no loudspeaker handling is necessary.

The above-ground mounting by its very nature does not provide for the free movement of cars over the theatre area which is inherent in the underground type of system. Damage to posts and speakers sometimes obtains as a result of poor driving.

The above ground type also requires that at least one window in each car be kept open for optimum intelligibility, and in this respect the disadvantages correspond to those associated with the system employing the underground type of unit.

Either a metal or wooden baliie may be utilized, but either should have direC< tional characteristics, so that interference from one speaker to nearby cars is minimized.

The weather-proof badlle is recommended where a metal battle is desired. The baffle is designed to accommodate the unit, and is of sturdy construction. The unit has directional characteristics, which are essential to this type of loudspeaker layout if interference from any one speaker to nearby cars is to be minimized.

46/14 2-WIRE


space between each pair for the parking of two automobiles. in such a set-up, the speakers are conveniently placed well within the reach of the occupants of the car. The underground circuit for the speaker system is composed of Not 14, 2-wire parkway cable. As a safety factor, base of the standards may be illuminated.

Where it is not desired to employ the metal baffle, a satisfactory and lowercost substitute has been used in the form of a wooden combined bathe and weatherproof housing made by outside suppliers specializing in this type of product. These batiies are satisfactory from a performance standpoint provided the proper directional characteristics are obtained through correct design.

The underground type of speaker does not have the sound reproduction qualities of a central speaker system but has an advantage over the in-car type of speaker, inasmuch as but one speaker is required to service two cars.

Advantages of this method of distribution include (1) fewer attendants are required, (2) movement and placing of cars is not so critical, since they can drive over the grille, if necessary, to facilitate placing and exit, (3) no loud speaker, handling, plug-in, and so forth, are involved.

It is, therefore, less costly, both from the standpoint of a lesser number of speakers and loss through theft.

The disadvantages of this system are (1) high installation cost, (2) difficulties arising from water, dirt, and pebbles getting into the speaker units, and (3) the necessity of keeping at least one of the car windows open for good reception.

In this form of sound distribution system, each unit is intended to serve two adjacent cars. Each unit should be mounted in a suitable housing underground, and the entire assembly contained in a concrete bowl or cavity over which is placed a metal grille through which the sound energy emerges to the
1945 Theatre Catalog, 4th Edition, Page 505