Projection engineering (Sept 1929-Nov 1930)

Page 54 Projection Engineering, September, 1929 the musical scale. This can be done at the will of the operator and without disturbing the lower middle and bass tones. Wright-De Coster dynamic speaker The Tone Modulator is designed to be connected between the phonograph pickup and the input of the audio amplifier. It readily lends itself for use in connection with sound equipment in theatres. The Tone Modulator is priced at $7.50. THE "FOTO-VOICE" EQUIPMENT The Foto-Voice Synchronizing Unit as herein illustrated is a sturdily constructed iron stand supported by three adjustable iron legs, and on which is mounted a unique worm reduction gear and stabilizing assembly. On this a 16-inch balanced aluminum turntable is rotated by means ot a direct drive pinion shaft — the possibility of record slippage being eliminated by a depression machined in its center and a nickeled weight placed on the record at this point. The tone arm is of mahogany and swung in carefully machined bushings for perfect freedom of movement — a high grade make of electric pickup is employed — the assembly being properly balanced for maximum reproduction results. The driving medium is through a specially constructed adjustable shaft, which in turn is driven by a simple gear and bracket attachment at the projector. The complete unit requires only twenty inches of floor space and may be placed to either side of or under the rear of the projector lamp house. The Booth control panel provides for switching from one turntable to the other and from the booth to the Non-Synchronous Console, with a fader which permits absolute control of volume to the amplifier input. An auxiliary changeover switch is also supplied for location wherever most convenient to the operator. The Foto-Voice Non-Synchronous Console is a finely finished cabinet measuring 17" x 32" by 30" high — the front panel of this cabinet is hinged to open for greater convenience in operating and the top is arranged to be entirely removable if so desired. Two Bodine non-interference turntable motors are employed, each operated by individual switches that are mounted on a small bakelite panel which also carries instant changeover and fader control and effect button. The Booth Monitor Horn is a 7%-inch cone magnetic speaker mounted in a 12inch cabinet, and is equipped with individual volume control. The Amplifier is an entirely a-c-operated unit of well-known manufacture, and is r / °1 / capable of properly reproducing voice and music in any degree of volume required. The Speakers are of the dynamic a-coperated cone type, and are attached to two specially designed horn units with a 30-inch bell opening. Manufactured by The Foto Voice Company, 817-19 Granby St., Norfolk, Va. UNIVERSAL "KK" MICROPHONE The new model Universal Broadcast Station Microphone is now available through the New York and Chicago offices of the Gotham Engineering and Sales Co., or from the Universal Microphone Co., Inglewood, Calif. This is a superior two-button unit with solid back, stretched duralumin diaphragm and gold contact surfaces. The curve of response is unusually flat from 30 to 10,000 cycles, and the absence of bothersome "hiss" is notable. It can be supplied complete as shown in the photograph, equipped with ring desk mount, covers, and cord, or the microphones alone can be procured. ,f Universal 'KK" two-button microphone. This microphone is ideal for use in broadcast studios, public address work, announcements in connection with talking movie installations, or wherever the most perfect pick-up of the carbon granule type is required. The unit alone lists at $75.00, or complete with ring desk mount, covers, and cord, as shown, at $98.50. The new "Foto-Voice" synchronizing unit attached to standard projector. NEW ROLA DYNAMIC SPEAKERS New models offered by The Rola Company include the Rola electrodynamic units for installation by manufacturer or dealer in cabinet radio sets and electric phonographs, as well as the Rola units in talking picture installations, public-address and school systems. They also include three Rola cabinet loudspeakers for use with table receiving sets. In its display the Company is presenting for the first time two new Rola electrodynamic units and is also introducing further refinements and improvements in its "J" line of electrodynamic reproducers. The new Rola electrodynamics have a high output efficiency, obtained by the use of relatively high flux densities in the air gap. High flux densities are obtained without increase of field energizing power, through the use of very short air gap distances. The short, precision air-gap is made practical by a highly refined moving coil structure, together with extreme accuracy in the spacing of the pole pieces. Another improvement is the ventilating of the field winding which minimizes temperature changes. The new Rola ventilnted construction e'iminates dead-air insulating areas around the windings and results in a substantial reduction in operating temperature. The removable center-pole nose piece — an exclusive Rola feature which enables easy elimination of any magnetic particles which misrht enter the air gap — has been retained. The new "J" series of electrodynamic units with 7%-inch cones and adjustable center pole tip, have been further improved and refined. Chief among the new features is the laminated bakelite spider support, ventilated field coil and more effective slot openings behind the cone. Included in the "J" series are the Model "J-90" for field excitation from standard power-pack. The series also includes the Model J-110, a complete electrodynamic unit for light-socket operation with all sets and amplifiers. Other Rola electrodynamic units for manufacturers or dealers are wound to meet any voltage New Rola "Concert' Speaker. Dynamic current ratio and for use with any power pack circuit. In addition to the above units the Rola Company also provides the Rola Cabinet Loudspeaker Model 30-J — equipped for lightsocket operation with any table receiving set. The new "C" or Concert Series electrodynamic units are similar in all respects to the "J" types except for their 9-inch cone diameter. This increased cone size gives somewhat greater power capacity and is adapted particularly well to amplifiers using 245 tubes in push-pull combination. The new "R", or Auditorium electrodynamic unit, has a cone diameter of 12 inches. It possesses a magnetic field structure of great size and power und uses the full output of a type 280 rectifier tube. Among the Rola electromagnetic loudspeakers are the Rola Model 20 cabinet speaker — attractive in design and of established popularity. The Rola Model 15 New Rola "Auditorium' Speaker. Dynamic equipped with the same unit as the Model 20, furnishes high quality performance at moderate cost. The Rola Model M is the complete electromagnetic unit as installed in the Rola Models 15 and 20. NEW BEST THEATRE PICKUP A new phonograph pickup has been announced by the Best Manufacturing Company of Irvington, N. J., manufacturers of the famous BBL, Motor. One of the serious objections to pickups has been the damage they do to thi? records. When one first looks at the Best Theatre Pickup one would think its large size and tremendous weight would wear out the records even quicker than the other pickups. The Theatre Pickup, however, is so finely counterbalanced that just enough weight bears on the record for the needle to track