. The Bell System technical journal. Telecommunication; Electric engineering; Communication; Electronics; Science; Technology. A HIGH EFFICIENCY RECEIVER 141 as a tube of this character, viz., -^ units, where p is the density of air, c, the velocity of sound, and A, the The Coupling Air Chamber and Diaphragm In order efifectively to make use of horns as sound intensifiers it is usually necessary to couple the throat of the horn to the diaphragm through an air chamber. We shall first consider the effect of this air chamber on the sound output of the loud speaker. This coupling air
. The Bell System technical journal. Telecommunication; Electric engineering; Communication; Electronics; Science; Technology. A HIGH EFFICIENCY RECEIVER 141 as a tube of this character, viz., -^ units, where p is the density of air, c, the velocity of sound, and A, the The Coupling Air Chamber and Diaphragm In order efifectively to make use of horns as sound intensifiers it is usually necessary to couple the throat of the horn to the diaphragm through an air chamber. We shall first consider the effect of this air chamber on the sound output of the loud speaker. This coupling air chamber is generally of an indefinite conical shape of the type shown in Fig. 1. If we assume that this air chamber is so proportioned that â THROAT OF HORN DIAPHRAGM. IL_^ L Conventional type of coupling air chamber. the annular area, lirrt, is equal to the throat area, and that the di- aphragm is driven so that its displacement is paraboloidal, then, as calculated from formulae developed in appendix A, the mechanical im- pedance imposed by the air chamber and horn on the diaphragm is shown in the curves of Fig. 2. Here the ordinates of the curves ri and Xi are proportional to the resistance and reactance respectively, and the abscissae are equal to the product of the frequency and the radius of the diaphragm. Of particular interest here is the large decrease in the resistance with frequency, for ri, multiplied by the square of the velocity of the diaphragm, is the acoustic power delivered to the horn. For example, if the radius of the diaphragm were four centimeters, no sound would be emitted at 4,000 We have here one reason why most horn-type loud speakers fail to reproduce high frequency tones at sufficient intensity. Of course, in most cases the high frequency tones are further attenuated by the fact that the mode of motion of the diaphragm changes with frequency. The decrease in - "The Function and Design of Horns," by C. R. Hanna and J. Slepian, Journa
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
