. The Bell System technical journal . Fig. 1—Western Electric Companys 394-type condenser microphone. Western Electric Companys 394-type microphone are cut at right angles. Holes, tapered at the outer end to reduce resonant effects, are bored through the plate at the intersection of the grooves to form connecting passages between the air film at the front and the cavity at the back. In order to prevent the resonance which would result if the grooves extended into the portion of the chamber surrounding the damping plate, the outer ends are closed by an annular ring which is pressed over a shoul
. The Bell System technical journal . Fig. 1—Western Electric Companys 394-type condenser microphone. Western Electric Companys 394-type microphone are cut at right angles. Holes, tapered at the outer end to reduce resonant effects, are bored through the plate at the intersection of the grooves to form connecting passages between the air film at the front and the cavity at the back. In order to prevent the resonance which would result if the grooves extended into the portion of the chamber surrounding the damping plate, the outer ends are closed by an annular ring which is pressed over a shoulder on the plate. The surface of the damping plate is plane within 8 X 10^ inch. The departure from a plane in any individual case is determined commercially by the interference pattern developed when an optically flat plate is placed over the damping plate under test. * The Air Damped Vibratorv System: Theoretical Calibration of the ConilenserTransmitter, I. B. Crandall, Physical Rcvinc, June 191S, pp. 449-46U. 50 BELL SYSTEM TECH
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
