International projectionist (Jan 1963-June 1965)

New Ballantyne Amplification System Billings, Mont. Dear J. G.: We were interested in your explanation of the reasons for light mismatch in the last issue. But what about the difference in sound reproduction? T. Cravella in T. C— The sound reproduction can also call attention to the change from one projector to the other. This will occur if the sound from one projector is distorted or weaker than the sound from the other. Careful listening tests should be made of the sound-onfilm reproduction (both optical and magnetic) obtained with each projector. Run tracks of good quality ( preferably test films of piano music to test sound quality, continuous tones for output level ) , and do not depend on the projection-room monitor. Use earphones or send an experienced listener to check on the sound from the auditorium. Most modern sound systems employ small potentiometers for the photocell load resistance in the optical soundheads or their preamplifiers. The outputs of the two soundheads are matched by painstaking adjustment of these potentiometers while identical test loops are run simultaneously. Certain old-style systems depend upon exciting-lamp rheostats to adjust exciter voltage, and hence the brightness of the scanning beams. The correct procedure is to adjust both exciting lamps horizontally and vertically for maximum output, and then match the two outputs by reducing the greater one. just as the average observer can detect brightness differences as small 8 Shown above is the complete Ballantyne transistorized amplification system. Each cabinet measures only 26^4 in. high, 10 in. wide and 7x/2 in. deep. Ballantyne Marketing Transistorized Amplifiers for Higher Quality as 4 per cent, the average listener can, under favorable conditions, detect loudness differences as small as % decibel. The outputs of the two projectors should, therefore. be matched to within V2 db. Sound matching as close as this is greatly facilitated by the use of an output meter, of course. Many projectionists depend upon their sound-service engineers to equalize the sound outputs. Professional sound engineers have the experience, knowledge, and equipment to do the best job. But if one projector falls off in output at a time when the engineer is not available, the output of the "louder" projector can be temporarily reduced to match the other by wrapping several turns of clear film around the photocell, holding it in place with rubber bands. Under no circumstances should an exciter be deliberately thrown out of focus to attenuate output: distortion of the sound may result. Address your cards and letters to Sound Track, 1 645 Hennepin Ave., Minneapolis, Minn., 55403. International Projectionist A new, all-transistorized amplification system featuring greatly improved sound quality and flexibility in use has been announced by Ballantyne Instruments & Electronics, Inc., Omaha, Neb. Ballantyne is a division of ABC Vending Corp. Company officials said that while the transistorizing gives many features, the improvement in sound quality is most outstanding. They described the sound as true hi-fidelity with great clarity and presence. The new amplification system is manufactured in three units. Each unit measures only I1/*" deep x 10" wide x 26V4" high. The system eliminates all photo cells, vacuum tubes and relays. As a result of the use of transistor components, there is no problem of heat dissipation. A second feature is enormously improved reliability, because the transistors used in the Ballantyne amplifier are designed to operate well within power requirements, with a very safety factor. The new amplifier has undergone a thorough program of installation testing which began early last summer in theatres that include the shopping centers at Poughkeepsie, N. Y., Johnstown. Pa. and Youngstown. Ohio. iP July, 1964