International projectionist (Jan-Dec 1950)

3.5% distortion between 50 and 5000 cycles. Approximately 10 db feedback between the output and driver stages contributes to holding the distortion to this low value, and also serves to hold the output level substantially constant with variations in speaker load. A ramp station comprises two speakers and a junction box. The speaker housings are of die-cast aluminum, rugged enough to withstand being run over by an automobile without crushing. They are small in size and light in weight and are easily handled with one hand. The hook or neck construction was designed so the speaker c'an be hung on the car window, with the window almost closed, as would be necessary in rainy or cold weather. The volume control knob is of bright red plastic and is tamper-proof. A simple rheostat volume control is used in the voice coil circuit of the speaker. Drive-in Speaker Mechanisms The mechanisms used in these speakers are especially designed for drive-in use. All metal parts, including the magnets, are heavily plated with cadmium. The magnets are anchored to the frame ANSWER TO YOUR TECHNICAL PROBLEMS . . . The Altec Service Man and the organization behind him 161 Sixth Avenue, New York 13, N. Y. PROTECTING THE THEATRE— FIRST PLACE IN ENTERTAINMENT HEYER-SHULTZ DISTRIBUTED ONLY BY AUTHORIZED LEADING THEATRE SUPPLY DEALERS Manufactured by HEYER-SHULTZ. INC.. Cedar Grove. N. J. so that they cannot shift and cause the pole piece to move off center. The voice coil and diaphragm are waterproofed and constructed to withstand all outdoor weather conditions, including floods. A drive-in theater in Endwell, N.Y., was under water for three days, submerging all of the speakers and junction boxes. When the theater was finally reopened, all but three of the speakers played perfectly. The junction boxes are also of die-cast aluminum and have the same type of finish as the speakers. The post and road light gives a cone of light at the base of the post and projects an adjustable beam of light out into The non-operating, or gear side of a projector in a drive-in theater, showing the path of the compressed airline from the front wall to the projector. Another airline is hooked-up to the film side of the mechanism. From the wall the airline is reduced to Vi-inch copper tubing. The hump shown in the tube, as it curves upward and down to the projector, serves two purposes: (1) it provides flexibility of the tubing to absorb vibration and to permit any possible change in projector tilt, and (2) affords the projectionist unobstructed access to the side of the projector at the front. the driveway in the shadow area between the rows of parked cars. The junction boxes are available with or without tins feature. The miniature 28-volt, .17-amp lamp is supplied by a 32-volt power transformer located in the projection room, with the voltage dropped through specified line resistors. The lamp was designed for airplane use and has a rugged shockproof filament assuring long life. This type of lighting eliminates any apprehension on the part of the automobile driver who. is obliged to turn off his headlights on driving into the theater. There can be no fear of hitting an unseen person or object, because each roadway light serves continuously to usher the driver safely toward a parking space. The pattern of elongated lighted areas in the roadway follows the curved contour of each ramp. The over-all effect, including the lighted areas at the base 30 INTERNATIONAL PROJECTIONIST • MARCH 1950