International projectionist (Oct 1931-Sept 1933)

June 1933 INTERNATIONAL PROJECTIONIST the cell has no effect on the cell characteristics. Thus, by testing both vacuum and gas-filled cells under this same set of conditions, the true quality of these cells can be measured and compared. For convenience, let us call this sensitivity the inherent or basic sensitivity. Technically, it is called "specific surface sensitivity." Effect of Gas When an inert gas is admitted to a caesium photo-electric cell it has two effects: (1) it increases the current output of sensitivity and (2) at the same time introduces the factor of glow voltage. By controlling the amount of gas admitted the sensitivity of the cell can be multiplied as much as five times the basic sensitivity, but the greater the amount of gas admitted, the more the glow voltage is lowered. In speaking of glow voltages there are two types of conditions under which this can be measured. The first condition, one which is of very little interest to sound equipment manufacturers, although it is frequently used by certain manufacturers of photoelectric cells, is the dark glow voltage or the voltage at which the cell glows when dark. However, inasmuch as this voltage drops considerably when the cell is subjected to light, the dark glow voltage has little significance from the point of view of the manufacturer of sound equipment. The glow voltage he is interested in is the voltage at which the cell ionizes or glows under normal conditions of use. For this reason the glow voltage used on Visitron Cells is what we call the "light glow voltage." This is the point at which cells will glow when subjected to the normal amount of light used in sound heads. Cells of relatively low basic sensitivity can be made to give a large output at 90 volts by increasing the pressure of the gas in them, but this results in a lowering of the glow voltage so that the danger of having the cell glow during operation is greatly increased. Another disadvantage is that the reproduction from a cell of this kind is of poorer quality than from a cell having high basic sensitivity and high glow voltage. In other words, the higher the basic sensitivity the higher the glow voltage can be made and still get high output and superior reproduction. It is obvious from this then, that in gas-filled cells, high output alone does not necessarily mean high qua]it\\ Many cells rated at glow voltages of 180 or more are rated at the dark glow voltage. Visitrons, however, are always rated at the light glow voltage which gives a truer picture of the actual quality of the cell. The higher the glow voltage, the better sound reproduction the cell will give and the longer the cell will last. Thus, although the sensitivity of the cell is the most obvious characteristic by which cells can be tested, from the point of view of the manufacturer of sound equipment a no less important characteristic is the glow voltage. What J bout Tell Hiss'? In the last analysis, the whole matter boils down to the basic sensitivity of the cells in question. If the cell has a sui!iciently high basic sensitivity to start with, the amount of gas necessary to raise the sensitivity to a point that will give good sound reproduction will still not lower the glow voltage to a dangerous point. As for the much-discussed "cell hiss," a term commonly applied to a hissing sound issuing from the loudspeakers, our experience has been that cells in which the output is obtained by considerable gas amplification and which have a correspondingly lower glow voltage are apt to be responsible for some ofs this noise ; whereas other cells which have a greater surface sensitivity^ and which can be operated at a voltage farther below the glow point, do not exhibit this characteristic. FAKE PRESS REPORTS ANENT RACKET INVESTIGATION 'p KEATING of the impending Senatorial investigation into racketeering, the New York World-Telegram recently front-paged a story having a Washington dateline in the course of which the affairs of Local 306 were given great prominence, the implication being that one of the first jobs of the investigation committee would be to inquire into the "rotten" conditions prevailing in Local 306 and other unions. Although investigation by International Projectionist tended to show that this story, despite its sensational handling by the World Telegram, evidenced gross exaggeration, practically every motion picture trade paper promptly "lifted" the story and rewrote it for industry consumption. So obvious is it that racketeering is conspicuous by its absence in the affairs of Local 306 today that the World-Telegram, which has used Local 306 for many a juicy story and shows great reluctance in letting the story die, has been forced to turn to the case of the permit men as a hub upon which to center its attack upon the 306 leadership. Forced to recognize judicial decisions favorable to both Local 306 and the I. A. in cases which it practically tried in its news and editorial columns, the WorldTelegram has been hard-pressed ta keep the Local 306 pot boiling. \ Labor Not Singled Out While it is true that labor unions will come under the eye of the investigating committee, it is also true that labor unions will get no more and no less attention than other groups and individuals. As a matter of fact, the biggest racket at the moment is that which has newspapers selling out tofinancial interests who control advertising expenditures. It is no secret around New York that powerful financial interests within and without the industry are out to "get" amusement unions; but it is not to be expected that the U. S. Government will lend a helping hand in these efforts. The harm in the World-Telegram story resulted when all the industry trade papers "lifted" the item and, without bothering to make even one phone call, promptly rewrote it and made a mess of what was already a built-up yarn. Possibly the industry trade papers would carry no news if daily newspapers were not published. — J. J. F. What is the economical average amperage used in the various types of lam.ps? Low Intensity Lamps 15 to 20 amperes Hi-Lo Intensity Lamps 60 to 70 High Intensity Lamps 120 to 200 State Associations Prove Their Worth N outstanding development of organization work during the past year is the demonstrated efficiency of state associations in matters of direct concern to a given state, as contrasted with the apparent inability of larger bodies — such as two, three, or more states — to get anything done. Invariably, the larger the group, the more scattered the territory, the more diverse the interests and the more pronounced the lack of coordination. Particularly in legislative work was the worth of the state association demonstrated. While not always successful in carrying their objectives, state associations easily outclassed those units which, numbering among their ranks representatives of more than one state, found the load of conflicting interests nmch too tall an obstacle to hurdle. Effective state organization has often been the means for inaugurating policies which subsequently provide the basis for similar activity on a broader scale. The future development of state associations into highly useful cogs in the machine that is the International seems assured. — J. J. F.