International projectionist (Jan 1963-June 1965)

are the voltage-gain tubes. But the faint bluish glow sometime seen in power tubes, and which flickers with the varying le\el of the sound being reproduced, is entiieU normal and does not necessarib indicate excessive "gassines9. Except for the replacement of noisj volume-control potentiometers, damaged in-car speakers cannot ordinarill\ be repaired in the theatre, but must be sent to a companj specializing in speaker re-coning, i Write to the manufacturer or to his distributor for advice before \ou need work done! i V torn or punctured cone mended with a patch of adhesive tape cut from a plastic Band \'u\ will work temporarily, but it maj distort the sound b\ weakening certain frequencies and overemphasizing others. \ll speaker-post junction boxes should be brushed out clean at the beginning of the season when the speakers are connected, and again whenever damaged speakers are replaced. \ weatherproof junction box of responsible manufacturer is not likeb to admit enough dust during the 3-to-5-month drive-in season to require midseason cleaning. Naturally, a "spot check" is a good idea after a sandstorm or a spell of high winds which mav stir up clouds of dust! 120 V Dangerous in Junction Boxes \lo>t junction boxes are fitted with small lights which permit the patron to locate the speakers easily for removal and replacement on the hangers. Some boxes also have additional lamps for signalling concession attendant-. Ml of these lamps are ideally supplied 1>\ a 2-wire system COmpletelj independent of the sound circuitry, but in practice it is usual to have a common-ground 3-wire system. Une of the three wires is the "live" power wire for the post lamps, the second is for the sound, and is connected to the speaker transformers, while the third wire is the common ground shared by both the lights and speakers. It is recommended that 30-volt post lamps be used when the 3-wire system is employed. A pressure of 120 volts presents a hazard which would become positively dangerous in the event that the "earthed" ground becomes accidentia disconnected or electrically weakened. A patron handling a speaker case or other conductor connected to the common-ground wire might then receive a shock, or be seriously injured if he happens to be standing on wet earth. It is undeniably a time-consuming job to check all of the speakers in a 1000-or-2000-car drive-in. Such a check cannot be made every day without the help of a special crew : but we do suggest that such a check be made once a week, if possible, and all defective speakers replaced from the stock of spares. Phonograph records of good quality can be played in the projection building to furnish sound during the time it takes to inspect the speakers. The care and servicing of the projector soundhead units is. of course, exactb the same in a drive-in as in a conventional theatre. The soundheads may need more frequent cleaning because of the presence of gritty dust in the air; but in-drafts which sweep dust-laden air over the projectors can be minimized b\ using ground and polished optical glass in the projector ports, and a good grade of plate glass in the observation ports. iP 2»WE PROVED BYTEST...BYFARTHE BEST Arc Lamps and Rectifiers for Every Projector... for Every Theatre... The World's Finest HERE ARE THE FACTS SUPER CINEX ... The masterpiece of the most experienced projection lamp designer. No other lamp has even remotely approached its perfection from every point of view — mechanically, electrically, optically, hydraulically or its fine air-conditioned system. Its durability and stamina have been proved. More and more fine theatres and drive-ins are re-equipping with Ashcraft Super Cinex daily due to their fine reputation for perfect screen light and service. Current range with 1 3.6 mm carbon, 125-165 amperes. CORE-LITE ... the latest and most phenomenal producer of white light at lowest possible operating cost in the family of Great Ashcraft Arc Lamps. Same arc burner and arc controls as the SUPERCINEX. Same quality and built-in reliability. The lamp is optically designed to give greater white light distribution at less cost for carbons and electricity. There is none better— anywhere! 70-1 10 amp. CINEX 35/70 SPECIAL .. .The Great of the Ashcraft Arc Lamps is a modified Super Cinex. Like the Super Cinex no third element or relay lens is necessary regardless whether 35 mm or 70 mm film is being projected. Uses a 13.6 mm high intensity positive carbon at current ranges between 1 25 and 1 40 amperes. RECTIFIER ...THE SPECIAL CORELITE 7 2 PHASE HIGH REACTANCE RcCTIrltR . . . designed for the requirements of the Core-Lite lamp, this rectifier will give the best results. Low reactance 6 phase rectifiers should not be used. Certain motor generators, but not all, are acceptable. The specia Core-Lite S/1212 rectifier will give you long, excellent service with an absolute minimum of expense. Other Ashcraft rectifiers available for every power need. The cost is no more than for inferior rectifiers. SOLD EVERYWHERE IN THE UNITED STATES BY LEADING RECOGNIZED THEATRE SUPPLY DEALERS ;.S. ASHCRAFT MFG. CO., INC. • 36-32 38th STREET LONG ISLAND CITY 1, N.Y. eun \Tio.\AL Projectionist May 1963