Four channel sound reproduction system

Claim 2

A sound reproduction system comprising: means for generating stereophonically related right and left audio signals; means for combining said right and left signals to form at least four composite signals, a first composite signal being a differential signal formed by subtracting the left signal from the right signal, a second composite signal being a sum signal formed by adding the left signal to the right signal, a third composite signal being a sum signal formed by adding the right signal to the left signal and a fourth composite signal being a differential signal formed by subtracting the right signal from the left signal; phase shifting means operating over a predetermined frequency range for shifting phase of at least two of said composite signals to cause the first and fourth composite signals to have substantially the same phase and prevent any of said composite signals from being substantially 180* out of phase from the others; and at least four electroacoustic transducers so arranged as to define a listening area and supplied with said at least four composite signals respectively.

Claim 3

A sound reproduction system according to claim 1 wherein the electroacoustic transducers are substantially positioned at the apices of a tetragon and directed to the interior thereof.

Claim 4

A sound reproduction system according to claim 2 wherein, with the right and left signals designated as R and L respectively, the first of said four composite signals may be exprEssed by R- Delta 1L, the second composite signal by R+ Delta 2L, the third composite signal by L+ Delta 3R and the fourth composite signal by L- Delta 4R where Delta 1, Delta 2, Delta 3 and Delta 4 represent proportion constants each having a prescribed value falling within the range of zero to 1, the electroacoustic transducer placed on the right side behind the listener sitting in a quadrilateral listening area defined by said four electroacoustic transducers being supplied with the first composite signal, the electroacoustic transducer disposed on the right side ahead of the listener being supplied with the second composite signal, the electroacoustic transducer located on the left side ahead of the listener being supplied with the third composite signal, and the electroacoustic transducer positioned on the left side behind the listener being supplied with the fourth composite signal.

Claim 5

A sound reproduction system according to claim 3 wherein the phase shifting means shifts over a prescribed frequency range of 300 to 3,000 Hertz the phase of the first composite signal substantially by 90* in a prescribed direction and the phase of the fourth composite signal substantial-ly by 90* in the opposite direction, thereby preventing any of the sounds produced by the electroacoustic transducers from being substantially reversed in phase from the others.

Claim 6

A sound reproduction system according to claim 3 wherein the phase shifting means causes over the entire audio frequency range the first and fourth composite signals to have substantially the same phase, the first and second composite signals to be differentiated in phase substantially by 90*, the second and third composite signals to have substantially the same phase, the third and fourth composite signals to be differentiated in phase substantially by 90*, thereby preventing any of the sounds generated by the electro-acoustic transducers from being substantially reversed in phase from the others.

Claim 7

A sound reproduction system for use with a two channel source producing first and second audio signals and at least first, second, third and fourth electroacoustic transducers about a listener, with said first and second transducers being adapted to position at the front side of the listener and said third and fourth transducers at the rear side thereof, the combination comprising: first means connected to receive said first and second audio signals for combining said first audio signal with an amplitude portion of said second audio signal; second means connected to receive said first and second audio signals for combining said second audio signal with a portion of said first audio signal; third means connected to receive said first and second audio signals for combining said first audio signal with an out-of-phase amplitude portion of said second audio signal; fourth means connected to receive said first and second audio signals for combining said second audio signal with an out-of-phase amplitude portion of said first audio signal; fifth means for coupling the output of said first means to said first transducer; sixth means for coupling the output of said second means to said second transducer; seventh means for coupling the output of said third means to said third transducer; eighth means for coupling the output of said fourth means to said fourth transducer; and phase shifter means connected between at least one of said third and seventh means and said fourth and eighth means to provide a predetermined phase difference between the outputs of said third and fourth means to thereby decrease the opposite phase relationship between the inputs of said third and fourth transducers.

Claim 8

A sound reproduction system for use with a two channel source producing first and second audio signals and at least first, second, third and fourth electroacoustic transducers about a listener, with said first and second transducers being adapted to position at the front side of the listener and said third and fourth transducers at the rear side thereof, the combination comprising: first means connected to receive said first and second audio signals for combining said first audio signal with an amplitude portion of said second audio signal; second means connected to receive said first and second audio signals for combining said second audio signal with a portion of said first audio signal; third means connected to receive said first and second audio signals for combining said first audio signal with an out-of-phase amplitude portion of said second audio signal; fourth means connected to receive said first and second audio signals for combining said second audio signal with an out-of-phase amplitude portion of said first audio signal; fifth means for coupling the output of said first means to said first transducer; sixth means for coupling the output of said second means to said second transducer; seventh means for coupling the output of said third means to said third transducer; eighth means for coupling the output of said fourth means to said fourth transducer; and phase shifter means connected between at least one of said third and seventh means and said fourth and eighth means to provide a predetermined phase difference between the outputs of said third and fourth means to thereby decrease the opposite phase relationship between the inputs of said third and fourth transducers.

Claim 9

The combination according to claim 6 including first phase shifter means connected between said third and seventh means and second phase shifter means connected between saiD fourth and eighth means, with said first and second phase shifter means having phase shifting characteristics for providing across a predetermined frequency range between the inputs thereof, a phase difference of about 180*.

Claim 10

The combination according to claim 7 wherein said predetermined frequency range is about 300 Hz to 3,000 Hz.

Claim 11

The combination according to claim 7 wherein said first and second phase shifter means phase-shifts the inputs thereof at a predetermined frequency by +90* and -90*respectively.

Claim 12

The combination according to claim 6 including first phase shifter means connected between said third and seventh means and second phase shifter means connected between said fourth and eighth means, and including third and fourth phase shifter means respectively connected between said first and fifth means and between said second and sixth means, and wherein said first to fourth phase shifter means have phase shifting characteristics for providing over the entire audible frequency range between the inputs of said first and second phase shifter means a phase difference of about 180*.

Claim 13

The combination according to claim 6 wherein said first to fourth means include at least first, second, third and fourth potentiometers connected in series and each having a slidable arm, and wherein one terminal of said series connection adjacent to said first potentiometer is connected to receive the out-of-phase signal of first audio signal, the other terminal thereof adjacent to said fourth potentiometer is connected to receive the out-of-phase signal of said second audio signal, the junction of said first and second potentiometers is connected to receive said second audio signal, and the junction of said third and fourth potentiometers is connected to receive said first audio signal.