International projectionist (Jan-Dec 1947)

I « • i ; i » » 1 1 ' * ' * • Z 8 1 • I • 'i * "* * ' Rectifiers, projector motors and dowsers are controlled from top of front wall panel; center section controls stage curtains; lower panel includes houselights and front curtains. Small mercury switches are remote-controlled dimmer switches. At right is sound system fader, while at extreme right is the link circuit fadei which is connected to auditorium fader. for each projector lamp and two for the Brenograph effect projector. A Walker plastic projection screen has been installed and Super C'nephor lenses are used. The Huff Orthoscope lens system has been adapted to the regular lens system, which affords even illumination over the projection screen area. The Walker projection screen has been installed in such a manner to afford good visibility at all angles. The screen masking is a deep maroon velour, and the carpet on the stage in front of the project'on screen is a dark blue color. The electrical installation includes an emergency gasoline operated generator set, which is single and 3-phase, and is operated automatically when the power or lighting service ceases to function. There are five projectionists employed in the Crest Theatre: Gilbert Lahlum, chief; Donald Long, Arthur Wiley, Frank Petrich and Wayne Swank. Special locker and rest rooms have been pro vided for the projectionists, also all lavatory facilities. A special work room has been provided with vises and the proper tools so equipment repairs can be made at any time. Fiber glas Acoustical Absorption Instead of using plaster in the auditorium wall and ceiling areas, Fiberglas is used for acoustical absorption. A report of reverberation time measurements has been made by the Erpi division of Western Electric Co. and the optimum and measured reverberation times, together with the calculated coefficients of absorption of the glass wool material are given in Table A. This being the first time Fiberglas has been used for acoustical absorption, the writer thought it advisable to provide these coefficients for the benefit of the industry. The sound reproduction in the Crest Theatre is outstanding in every respect. Every seat in the auditorium is a good seat. 'Transvox'' Selective Expansion A special attachment has been affixed to the sound system, with selective expansion. This equipment is called "Transvox". The Transvox frequency response curve is continuously variable throughout the entire audio spectrum with a 12 db range. This is the first theatre in which the selective expansion circuit has been installed and by the use of this circuit the entire audio of sound reproduction is brightened and broadened 100%. The Transvox equipment is not on the market at the present time as it is still in the experimental stage, although the results are quite convincing and such an attachment will prove to be au automatic fader or an acoustical correction device in the future. Anyone interested in the construction of this theatre can set in touch with the Gilbert Lahlum, chief projectionist (also B. A. of I. A. Local 521), demonstrates how rectifiers are easily disconnected from prefab panel. Units are mounted on rubber wheels for mobility in servicing. TABLE A Measured Optimum Reverber Freq. in Reverber ation Glass Wool Cycles ation Time Absorption per Sec. Time Averages Coefficients 50 2.50 1.47 .40 60 2.40 1.45 .41 80 2.20 1.38 .42 100 2.10 1.37 .43 125 2.01 1.28 .45 250 1.70 1.17 .49 500 1.46 1.14 .50 1000 1.38 1.06 .52 2000 1.38 1.06 .52 3000 1.38 1.05 .53 4000 1.38 1.02 .55 5000 1.06 .52 6000 .99 .57 7000 .95 .60 8000 .83 .66 writer, R. H. McCullough, at Fox West Coast Theatres, 1609 West Washington Boulevard, Los Angeles 7, Calif. He will be glad to give further information in connection with the construction of this theatre. New Ampro 'Premier 20' 16-mm Sound Projector A new 16-mm sound projector, the Premier 20, compact and easily portable for home use, classrooms, industry, and average-size auditoria, is announced by Ampro Corp., Chicago, for March 15 delivery. The unit is equipped for both silent and sound film speeds, still pictures and reverse operation, with switches readily accessible on a centralized control plate. Standard pre-focused lamps, up to 1000 watts, are used. Coated F:1.6 lenses are standard, easily replaceable by either 1, 1%, 2V2, 3, 3% or 4-inch coated lenses. The sound optical system projects light from the exciter lamp directly through a semi-cylindrical lens, eliminating the mechanical slit and its attendant error. Many Operational Features A new feature is the swing-out gate which permits easy inspection and cleaning of the aperture plate and pressure shoe without disturbing lens focus. Other features include: long-wearing roller sprocket shoe assembly which opens and closes automatically with the film gate for easy, quick threading; quick-centering tilting control knob, and fast automatic rewind. The Premier 20 operates on 50-60 cycle, 105-125 volts A.C., and can be used with a converter on D.C. current for the amplifier only. Projector motor operates on either A.C. or D.C. Complete unit includes projector, speaker, lens, lamps, a 1600-foot reel and standard accessories. A 12-inch Jensen P.M. speaker is standard. Huge U. S. Patent Backlog A huge backlog of patent applications awaiting action, many of them film items, is reported by the U. S. Patent Office. The agency reported an 81 per cent increase in applications during the past year, with prospects gloomy that the situation will ease soon. Total number of applications awaiting action is 117,934, as compared with 64,890 at the same period of 1945. 12 INTERNATIONAL PROJECTIONIST • March 1947