GB1253044A - - Google Patents

Abstract

1,253,044. Loud-speaker enclosures; stereophonic systems. BOSE CORP. 29 Oct., 1968 [4 Dec., 1967], No. 51248/68. Headings H4J, H4R and H4X. A sealed cabinet of a loud-speaker system has a rear baffle inclined relative to a front panel and upper frequency sound is directed across the rear baffle in a beam having a rearward component perpendicular to the front panel and a lateral component substantially parallel to the front panel. A fluid-tight loud-speaker enclosure, Fig. 3, has rear baffles 33, 34 forming an angle of 120 degrees and on which are mounted full range loud-speakers 41, 42, 43, 44 and 45, 46, 47, 48 respectively. The front baffle has a single loudspeaker 31, also full range. Loud-speakers 42, 43, 44 are in series to form a first group, loudspeakers 45, 47 and 48 are in series to form a second group and loud-speakers 41, 46, 31 are in series to form a third group. The groups are connected together and the loud-speakers are co-phasally excited. The inside volume may be filled with fibreglass. Two such enclosures 15<SP>1</SP>, 16<SP>1</SP> (Fig. 2), each responsive to one channel of a stereophonic system, may be placed with the front baffles facing a listener and the rear baffles facing a reflecting wall. Alternatively, a single enclosure may be used, loud-speakers 41, 42, 43, 44 being connected to one stereo amplifier channel (Fig. 7) and loud-speakers 45, 46, 47, 48 being connected to a second stereo amplifier channel. A dividing baffle is then provided in the interior of the enclosure (Fig. 9, not shown). The loud-speaker 31 is connected to a centre output channel or is alternatively connected so that it receives a " sum " signal, e.g. by connecting its winding in series with windings of loudspeakers on the left and right rear baffles. Complementing means is associated with the system to establish a substantially uniform radiated power density for the system over substantially the entire audible frequency range. A complementing circuit 62, 63 (Fig. 6, not shown) is connected between the preamplifier and amplifier section of each channel (e.g. between the " monitor " and "recording" sockets, when the amplifier is switched to " tape monitor "). The complementing circuits each provide adjustable bass and treble lifts (Fig. 8, not shown), for the complementing function. In modifications the baffles may be tilted upward or downward. Different numbers and kinds of speakers may be used. The high frequency energy from the front loud-speaker may be attenuated electrically, mechanically or acoustically. There may be a single loud-speaker on each rear baffle and on the front panel, the one on the front panel being energized through an attenuating network that delivers about “ the high frequency energy to the front loudspeaker, compared with that delivered to each rear loud-speaker.