The Film Daily (1929)

THE Sunday, September 22, 1929 -22a DAILY NEW DEVELOPMENTS IN THE FAST GROWING FIELD OF SYNCHRONIZATION SOUND TIPS ON EQUIPMENT AND VARIOUS DEVICES ARE NOW AVAILABLE Use and Care of Vacuum Tubes Outlined by Sound Engineer Importance of vacuum tubes and their care is stressed by Fox West Coast Theaters in instructions to managers of the circuit, by R. H McCullough, the circuit's sound expert. Following are some of the pointers and instruction to managers, as listed in "Now," house organ of the circuit. All Western Electric vacuum tubes are guaranteed for 100 hours burning service. After receiving vacuum tubes, they should be tested immediately for defectiveness and returned immediately, if found defective, for replacement. We have found that most of our poor sound reproduction was caused by poor vacuum tubes. The life of the vacuum tube will vary in accordance with the amount of abuse to which it is subjected. However, we have tubes, which have given 3000 hours service, and are still good. It is of equal importance that the filament current be maintained at exactly the value indicated by the Electrical Research Instruction Book. The filament of an Amplifying Tube is heated by current from a Storage Battery of approximately twelve (12) volts pressure. If the filament current be too high, it will shorten the life of the tube. Do not allow amplifier tubes to operate with low filament current, as the volume will be low and the quality will suffer; therefore, operate amplifier vacuum tubes at their indicated values as specified. Rectifier Tubes Essentially, all rectifier tubes must be in good condition. A portion of the amplifier power comes from rectified alternating current. Rectifier tubes require the same care and attention as amplifier tubes. It is extremely important that the indicated filament current values be maintained, as given by Electrical Research Products, Inc. Pick-Up Noise The pick-up amplifier, called the 49-A, located underneath the projector mechanism is suspended in a spring cradle. This is for the purpose of absorbing the vibrations of the projector mechanism. If the P. E. C. amplifier touches any part of projector, mechanical vibrations will be picked up and carried through the amplifier and will be heard in the horns. It is very important to see that this cradle swings free of everything. Be sure all tubes are inserted into their sockets properly — otherwise, Sound Seen Highlights New inventions and developments in the sound reproducing field are expected to highlight the fall convention of the Society of M. P. Engineers to be held Oct. 7 to 10 at Toronto. Papers to be read cover a wide range of subjects in the sound picture field. you will encounter pick-up noise in the 49-A amplifier. Filaments in Series The 49-A and the 41 -A Amplifiers operate with the filaments of two or more tubes in series. In such cases the failure of a filament in one of the 239-A Tubes will extinguish all the tubes. It is necessary to inspect all the tubes to determine which one is at fault. W. E. Reproducer The present design of the Western Electric Reproducer is somewhat different than other makes. The entire casing is filled with oil. This is a very good method for dampening or smoothing out any tendency of excessive vibration on part of the needle. On the side of the case, opposite the magnetic poles, is a thin steel gold plated diaphragm to which the needle holder is attached. The flexibility of this diaphragm permits the needle sufficient freedom to follow the record grove undulations. It also acts as an armature. One of the magnet pole pieces is in the form of a circle. It extends around the edge of the steel diaphragm. The other magnet pole piece is double and is located opposite the center of the diaphragm — its end a few thousandths of an inch removed from the diaphragm. It has a coil wound upon each of its prongs, which are both, the same polarity. The movements of the needle, caused by the record groove undulations, will be reproduced in the flexing or binding of the diaphragm — the greatest effect of which will be concentrated at its center. And since the center pole piece is placed at a certain fixed distance from the center of the diaphragm, when it is at rest, it follows that the needle movements will be precisely reproduced in alternations of distance between the diaphragm center and end of center pole. Tube Failure Sign When the amplifier tube is about to fail, it will be perceptible that the weakness usually shows at one spot on the filament. This spot will glow W. E. DEVICE INSTALLED IN 21 MORE LONDON HOUSES London — Western Electric sound apparatus has been installed in 21 more houses here. Houses equipped are: Elite, Kingston; Alcazar, Hounslow; Britannia, Camden Town; Scala Croydon; Clock Tower, Wandsworth; Picture House, Ipswich; Palace, Andover; Gaiety, Southampton; Park Hall, Cardiff; New Plaza, Morecambe; Coliseum, Harrow; St. James', King's, Lynn; Grosvenor, Oldham; Lyseum, Edinburgh; Theater Royal, Blyth; Coatsworth Hall, Gateshead; Empire, St. Annes; Empire, Wigan; Palladium, Manchester; Rialto, Liverpool; and Cinema, Stockton. Russia Purchasing RCA Sound Equipment American sound picture equipment is being purchased by Russia for installation in Soviet theaters following negotiations between Akmino and E. E. Bucher, executive vice-president of RCA Photophone. The first sets will be installed in Moscow. Sound for Renville, Minn. Renville, Minn. — Sound equipment has been installed at the Garden, according to Manager Parsons. An Arctic Nu-Air ventilating system also has been installed. Ealand Joins Vitaphone Detroit — Tom Ealand, has been appointed short subject representative for Vitaphone here, succeeding Frank Gebhart, who has been transferred to the home office. more brightly than the rest of the filament. It is imperative to replace the tube with a new one immediately upon detecting the warning sign. Interruptions usually occur through negligence, and it is likely that the filament of a vacuum tube will fail in the middle of a sound reel, if you do not properly check the filament. Noisy Tubes Only occasionally will a noisy tube be found. Such tubes rarely give trouble except in the first stage of amplification. The frying and hissing noise is caused by the filament throwing off electrons at an irregular rate. . If you suspect a noisy tube, set the fader at zero. Then, if there is any noise, change the tube in the first stage, from the first amplifier, exchanging it for a tube from elsewhere or insert a spare tube. T-A-C DUAL SOUND DEVICE HAS MANY NOVEL FEATURES __ Theatre Acoustic Distributing Corp., New York, formed by Levy Bros, is distributing nationally a dual sound apparatus which is especially designed for small theaters. The combination disc and sound device can be installed within four to six hours. It consists of two turntables attached to the pedestal of the projection machine, which are driven by a main shaft of the projector through a short universal shaft. Shocks and vibrations are eliminated, it is claimed, by special absorbing devices. Only two gears of the device are used and mounted on ball bearing shafts which are in oil baths. The sound on film attachment is mounted directly under the head of the projector and has two mooring parts mounted on ball bearings thus preventing, it is said, any flutter due to projection vibrations. Features of the company's sales plan is a free service guarantee of 90 days and promise of immediate delivery. The prices of the various types of equipment offered by the company vary according to the apparatus selected. The sound on film and disc combined is listed at $2,600; with $2,850 additional for the nonsynchronous device, sound on film without disc sells for $2,250; disc apparatus without sound heads $1,850. Among houses already equipped with the company's product are Colonial, Portsmouth, N. H.; Strand, Lewiston, Me.; Star, Concord, N. H.; Bergen, Tenafly, N. J.; Proctor's 23rd St., New York; and Clinton Square, Albany. New Amplifier Ready Cleveland — Radio Receptor Company of New York, manufacturers of Powers amplifiers, is maintaining local headquarters with the Oliver M. P. Supply Co. John B. Dutton is the district engineer in charge. He announces development of a new secondary or double channel amplifier for theaters under 1000 seats. By special arrangement with Oliver, Dutton will supervise all installations of the Oliver Reproducer, developed by E. E. Oliver, and sold through the Oliver M. P. Supply Company. Reopens with Talking Pictures Middletown, Conn. — The Capitol, recently acquired by Warner's, has been transformed into a talking picture theater. Wire Lansing House Lansing, Mich. — The Orpheum has been wired with De Forest equipment.