GB433211A - Improvements in or relating to electroacoustic translating devices - Google Patents

Abstract

433,211. Loud-speakers. ELECTRICAL RESEARCH PRODUCTS, Inc., 195, Broadway, New York, U.S.A.-(Assignees of Blattner, D. G.; 165, Laurel Hill Road, Mountain Lakes, New Jersey, U.S.A.) Feb. 10, 1934, No. 4430. Convention date, Feb. 28, 1933. [Class 40 (iv)] An electroacoustic device, such as a loudspeaker, comprises a plurality of different sized diaphragms each adapted to translate a separate band of frequencies within the audio-frequency range and having the same angle of distribution at corresponding relatively high frequencies in the frequency bands translated thereby, i.e. the product of the diameter or equivalent diameter of any diaphragm and a frequency within the band translated thereby is equal to the product of the diameter or equivalent diameter of any other diaphragm and a frequency within the band translated thereby, the said frequencies being the same per cent of the maximum frequency translated by the diaphragms corresponding thereto. Fig. 1 shows one form of construction in which disc diaphragms 11, 12 and 13 are mounted by flexible annuli 14, 15 and 16 in a baffle 10. The diaphragm 11 may be adapted to cover the range from 3000 to 15,600 cycles, the diaphragm 12, 575 to 3000 cycles and the diaphragm 13 up to 575 cycles. Each diaphragm is operated by a separate actuating unit, each unit being connected to a corresponding channel of a multi-channel electrical filter, Fig. 2, (not shown). If desired, a fourth diaphragm could be employed covering a range from 21 to 110 cycles in which case diaphragm 13 would cover a range from 110 to 575 cycles. Fig. 4 shows a modification employing three coaxially disposed moving coil loud-speakers, the horn 28 and diaphragm 27 of the speaker 23 and the frusto-conical diaphragm 26 of the speaker 22 being disposed within the diaphragm 25 of the speaker 21. According to a further modification, Fig. 6, a high frequency loud-speaker 29 comprising a relatively small diaphragm 34 and exponential horn 35 is supported by a strut 36 from a flange 37 on the exponential horn 33 of a low frequency speaker 30 having a large frusto-conical diaphragm 32 associated with the horn 33. The speakers 29, 30 are connected with corresponding channels of a filter 31.