FilmIndia (1940)

Resume Of Information For Technical minded Readers LANSING Shearer Sound System For Better Theatres Power Amplifiers The power amplifiers are AC operated, negative feedback stabilized type and represent the very latest design. They have a hum level far below the minimum required theatre sound work. Frequency response is exceptionally fine and equal to the very high standards demanded by the associate equipment. At full power output rating the total harmonic distortion is less than 1%. Amplifiers are so arranged that condition of •each individual tube may be determined by a meter. All necessary controls are mounted on the amplifier panels. The amplifiers are designed to give long service under world-wide conditions of lemperaturej humidity, etc. Dividing Network The dividing networks as specified with the various systems are for dividing the amplifier power between the high and low frequency speakers. The standard cross over frequencies are 400 and 500 cycles depending on the system ordered. Monitor volume control, test and emergency switches are all mounted on the front panel. Monitor Equipment A single stage bringing type amplifier for feeding the Monitor speaker is mounted on the dividing network, chassis and has a volume control which is independent of the balance of the system. The Monitor speakers are of a type suitable for this work and are mounted in a base reflex cabinet. Loudspeaker Field Supplies The field supplies listed and supplied with the various systems are carefully designed and built to give best results with the various speakers. Each Field supply is complete ( Contd. from last issue ) in itself and will supply current for one or more units as specified. In each case the field supply has enough capacity to supply current to the monitor speaker as well as the stage speakers. Field supplies are complete with pilot light and necessary controls. Exciter Lamp Supply The excitor lamp supplies are made in sizes suitable for the various systems. They furnish filtered DC for the exciter lamps and filament supply for both preamplifiers. They are of the copperoxide type, heavily filtered and mounted on individual chassis. Each has sufficient capacity to operate the recommended apparatus without overloading. The Stage Loudspeakers The Lansing-Shearer speaker systems have been engineered to Romola in "Khazanchi" a Pancholi production. meet the conditions necessary for perfect sound reproduction in various size theatres from the smallest to the largest. The basis of all Lansing-Shearer systems is the use of low frequency horns (bins) together with high frequency horns of balanced design to fit the needs of the individual installation. The low frequency horns consist of one or more 80" bins, which may have from 2 to 4 low frequency speaker units depending on the size of system. The high frequencies are projected through a multicellular horn which may consist of from 8 to 18 cells. One or more high frequency speaker units are used through straight or "Y" throats. The multicellular horns are not die cast, but are made of heavy guage steel with all space between cells packed with acoustically inert material which assures absolute freedom from distortion. Each horn system comes complete with woodwork wings, terminal box and necessary cable for connecting the speaker units to the terminal box. Instructions Clear, concise installation and operating instructions are included in every shipment. The factory engineers are at the service of buyers for any special information bearing on Lansing-Shearer Horn systems. The Lansing Manufacturing Company operate a modern factory fully equipped with fine; precision tools fcr metal work and also a fully equipped wood working plant for making the low frequency horns and cabinets. Every part from the smallest transformer to the largest pieces are manufactured by Lansing in their own plant. (To be continued) 52