GB358044A - Improved damping means for a sound reproducing diaphragm - Google Patents

Abstract

358,044. Diaphragms. PODSZUS, E., 33, Sch÷neicherstrasse, Friedrichshagen, Berlin. June 25, 1930, No. 19338. Convention date, June 26, 1929. [Class 40 (iv).] A diaphragm b is damped by springs h or like members of high elasticity (e.g. tungsten, steel) which are in contact with the diaphragm at the loops of the overtones of the natural vibrations. The damping may be selected to take up the increase in amplitude due to the resonance of the diaphragm by selecting the thickness of the wire, the diameter of the springs h, and the area of contact. The position of the loops of the overtones may be found by sprinkling sand on the vibrating diaphragm, the sand collecting at the nodes and leaving the loops clear. The springs h may be also placed in other positions and when used on both sides of the diaphragm, may serve as the diaphragm supports. The damping springs are preferably not placed at the positions of greatest amplitude, e.g. the centre portion of the diaphragm, but in the zones dividing the radius in medial section. The springs may be made of wire bands or strips not more than 1/100 mm. thickness, wound in coils of diameter a small fraction of a centimetre, and, where not supporting the diaphragm, are mounted on the supporting members a, c, placed a millimetre or so distant from the diaphragm. They may be in loose contact or glued to the diaphragm. The damping-effect may be increased if some of the springs are in friction contact with each other.