Acoustics – Plural diaphragm sound sources – Plural chambers
Patent
1991-04-29
1993-07-13
Gellner, Michael L.
Acoustics
Plural diaphragm sound sources
Plural chambers
181153, 181154, 181155, H05K 500
Patent
active
052275914
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a loudspeaker arrangement defined in the introductory section of the appended patent claim 1.
In principle a stereophonic sound effect is nowadays created so that a musical performance or the like is recorded with two microphones that are advantageously located at a distance from each other, the said distance corresponding to the interval between human ears. The voltage signals from the microphones are amplified in respective amplifiers, and recorded, generally each sound channel separately, to a suitable means such as a record or tape. Correspondingly, the obtained record is played by amplifying the sound signal recorded in each channel in respective amplifiers, and by reproducing the sound via loudspeakers placed at a suitable distance.
The problem with the current system is that a stereo effect is generally formed only if the loudspeakers of the separate channels together with the listener form an isosceles triangle, so that the listener is located at the point of the triangle. Thus the creation of a depthwise expanded stereo effect within a large space is difficult.
Another problem is that the current arrangements require at least two loudspeaker units.
In the prior art there is known, from the FI patent publication 35,014, an arrangement where two normal stereo channel signals are electrically transformed into three different outlet signals, which are amplified and fed out via three loudspeaker units. To a certain degree this type of arrangement creates a stereophonic impression of depthwise extension within the given space.
The problem with the aforementioned arrangement is that it requires three loudspeaker units and a special amplifier for producing three outlet signals out of two normal stereo channel signals.
The biggest drawback with the present-day stereo loudspeaker arrangements is that they are difficult to place within the given space so that the listeners on different sides of the space could get a clear stereophonic impression of the record being played. On the other hand, if the arrangement according to the above described Finnish patent publication is applied, special equipment is required.
A further drawback with current stereo loudspeaker arrangements is that the created stereophonic sound effect hardly gives an impression of a depthwise expanded sound. The sound field seems to come flat out of the wall. In a system of two loudspeakers, it is true, it is to some degree possible to create a depthwise extension of the sound field, particularly within the medium level of the loudspeakers, but the impression of the space of the performance remains, however, inadequate, and greatly dependent on the imagination of the listener.
The object of the present invention is to eliminate the above mentioned drawbacks. The loudspeaker arrangement of the invention means a substantial improvement in the creation of a threedimensional stereo sound effect within a given space.
The loudspeaker arrangement of the invention characterized by the features enlisted in the patent claim 1.
The loudspeaker arrangement of the invention for creating a three-dimensional stereo sound effect is to be placed at a suitable distance from sound-reflecting surfaces. According to the invention, the loudspeaker elements of the left and right channels in the loudspeaker arrangement are located within one and the same loudspeaker unit, where they are separated from each other by means of a zone corresponding at least to the size of the interval between human ears, and where they are arranged to radiate towards different sides of the said zone, in a similar fashion, within 180.degree. circle sectors, so that the sounds reflected from the surfaces, together with the sounds coming directly from the loudspeaker unit, create a depthwise expanded, threedimensional stereo sound effect, mainly within the sector expanding away from the loudspeaker unit.
In a preferred embodiment of the invention, the bass elements of the left and right channels are placed vertically with the cones towards opposite directions, so
REFERENCES:
patent: 3914549 (1975-10-01), Bose
patent: 3931867 (1976-01-01), Janszen
patent: 4673057 (1987-06-01), Glassco
Dang K.
Gellner Michael L.
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