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INTERNATIONAL PROJECTIONIST
VOLUME X
NUMBER 2
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FEBRUARY 1936
Function and Application of Sound System Analyzer Equipment
By A. C. SCHROEDER
MEMBER, LOCAL UNION 150, LOS ANGELES, CALIF.
PROJECTIONSTS are becoming analyzer conscious, intensely so, and are asking all sorts of questions regarding them. For months I have been asked about the different instruments— what they will do, what this, that and the other one will do; or is this one worth more than some other one? Any of the good analyzers will undoubtedly give satisfactory service. What to recommend to the house along this line will have to be decided by you yourself. Do I hear you say, "Well, you're a big help"? Let's see what can be done about it.
Correct Usage Important
When a theatre buys an analyzer, the thing is valueless unless you, the projectionist learn how to use it. After you do learn, you are in a position to know which one you want, so the thing to do is to learn what these units are for, how they work and how to interpret the results. To tell all about this is a
big order for one article so in this installment we will just cover the high spots.
The analyzer is a device whereby the circuits are extended from the tube sockets to one or more sockets on the analyzer, and to one or more meters. The extension is made by putting a plug into the socket in the amplifier. The plug is on one end of a cable, the other end going to the analyzer sockets.
Adapters are furnished so that the plug can be inserted in sockets made for tubes having from four prongs up to those having eight prongs, and adapters for the erpi 211 and 242 type tubes may be had. Instead of four wires in the cable, as in Fig. 1, the cable will have eight wires, and the plug will have seven or eight prongs. Fig. 2 shows how the
Diagrams referred to herein appear on the next page
sockets in the analyzer are connected to the cable. The wires extending to the right represent the cable, at the other end of which is the plug. The gadget on the end of the eighth wire is a clip for the terminal at the top of some tubes.
Meter Equipment
Very often an analyzer has only one meter and is connected to the various circuits either by switching or by plugging a pair of test leads into different jacks. The meter is connected through a number of switches so that multiplier resistors of various values can be used in series with the meter for voltage tests, and so that shunt resistors may be used for different ranges of current measurements. A copper-oxide rectifier is included and allows the d.c. meter to measure a.c. voltages or currents. This is used because the ordinary a.c. meter draws too much current for testing sound equipment and radios.
Although the cable has eight or nine
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