GB1363759A - Loudspeaker apparatus - Google Patents

Abstract

1363759 Loud-speakers FASER-UNDKUNSTSTOFF-PRESSWERK ROMEN KG 5 Nov 1971 [25 Nov 1970] 51510/71 Heading H4J A loud-speaker comprises a low-frequency, e.g. bass, diaphragm which is driven via an enclosed air space by a second diaphragm driven directly by vibratory energizing means and which is intended to cover the range of frequencies above that of the first diaphragm. In a coaxial arrangement of conical diaphragms (Fig. 1) the low and the higher frequency diaphragms 1, 2 are flexibly supported by a chassis 6, and the higher frequency diaphragm 2 is driven via a moving coil arrangement situated in an enclosed air space bounded by parts of diaphragms 1, 2, chassis 6 and bellows 8, 10. The area of the low-frequency diaphragm 1 bounding the air space is made smaller than the corresponding area of diaphragm 2 so that vibration amplitude amplification takes place at the low frequencies transmitted by the air space. The moving coil arrangement may be housed within the cone 2 instead of in the air space (Fig. 2, not shown). In a composite diaphragm (Fig. 3) chassis 22, 23 flexibly supports lowfrequency diaphragm 26, 20 which in turn flexibly supports higher frequency diaphragm 17. In a further arrangement (Fig. 5) the diaphragms are separately mounted and area coupled by an air pipe 31. The enclosed air spaces may be connected to the atmosphere via a small aperture to allow for changes in atmospheric pressure. More than one lowfrequency diaphragm, each having a different resonance frequency, may be coupled by the enclosed air space to the higher frequency diaphragm.