Quadraphonic reproducing system with gain control

Claim 2

In apparatus for reproducing on four separate loudspeakers adapted to be arranged around a listener four individual audio information signals contained in first and second composite signals each of which includes a combination of At least three of said audio information signals with preselected phase and amplitude relationships, the combination comprising: first and second input terminals to which said first and second composite signals are respectively applied, a first signal combining network connected to said input terminals and operative to derive by combining the signals in said composite signals with preselected amplitude and phase relationships four output signals predominantly containing signals representing the information in respective ones of said four individual signals each accompanied by lower level signals representing information contained in others of said individual signals, signal coupling means including first, second, third and fourth variable gain amplifiers for separately coupling one of said output signals to a respective one of said four loudspeakers, and gain control means for varying the gain of said variable gain amplifiers so as to selectively amplify the output signals or signals instantaneously predominant relative to the remaining output signals, said gain control means including control circuit means connected to said first and second input terminals and operative to derive from said first and second composite signals four auxiliary signals containing audio information substantially corresponding to the audio information contained in corresponding ones of said four output signals, and means for continuously comparing the instantaneous amplitudes of said auxiliary signals.

Claim 5

In apparatus for reproducing on at least three sound reproduction devices an equal number of individual audio information signals contained in first and second composite signals each of which includes a combination of at least three of said audio information signals with preselected amplitude and phase relationships, the combination comprising, signal combining means to which said first and second composite signals are applied and operative to produce output signals equal in number to the number of individual audio information signals contained in said composite signals and each predominantly containing signals representing the information in a respective one of said individual audio information signals, and signal coupling means for coupling said output signals to respective ones of said sound reproduction devices, said signal coupling means including control signal generating means connected to receive said first and second composite signals and operative to derive therefrom auxiliary signals of substantially constant amplitude regardless of the amplitudes of said composite signals, means for combining said auxiliary signals to produce control signals corresponding to said audIo information signals and at any given instant to produce one or more control signals corresponding to the predominant audio information signal or signals then present in said composite signals, and amplitude-modifying means connected to receive said control signals and operative in response thereto to enhance the amplitude of the output signal or signals which instantaneously contain predominant audio information signals relative to the other output signals.

Claim 6

In apparatus for reproducing on at least three sound reproduction devices an equal number of individual audio information signals contained in first and second composite signals each of which includes a combination of at least three of said audio information signals with preselected amplitude and phase relationships, the combination comprising, signal combining means to which said first and second composite signals are applied and operative to produce output signals equal in number to the number of individual audio information signals contained in said composite signals and each predominantly containing signals representing the information in a respective one of said individual audio information signals, and signal coupling means for coupling said output signals to respective ones of said sound reproduction devices, said signal coupling means including control signal generating means connected to receive said first and second composite signals and operative to derive therefrom auxiliary signals of substantially constant amplitude regardless of the amplitudes of said composite signals, means for combining said auxiliary signals to produce control signals corresponding to said audIo information signals and at any given instant to produce one or more control signals corresponding to the predominant audio information signal or signals then present in said composite signals, and amplitude-modifying means connected to receive said control signals and operative in response thereto to enhance the amplitude of the output signal or signals which instantaneously contain predominant audio information signals relative to the other output signals.

Claim 7

Apparatus according to claim 3 wherein said amplitude modifying means provides a signal transmission function which remains at a normal level when substantially all of the audio information signals contained in said composite signals have approximately the same amplitude.

Claim 8

In apparatus for reproducing on four separate loudspeakers adapted to be arranged around a listener four separate channels of program information contained in first and second composite signals respectively containing first and second component signals representing the program information in first and second ones of said channels, and each containing component signals representing the program information in third and fourth ones of said channels, the combination comprising: first and second input terminals for receiving said first and second composite signals, respectively, a first signal combining network connected to said input terminals and operative to derive from said composite signals four output signals predominantly containing signals representing the information in respective ones of said four channels each accompanied by lower level signals representing information contained in others of said channels, signal coupling means including first, second, third and fourth variable gain amplifier means for receiving and separately coupling a respective one of said four output signals to a respective one of said four loudspeakers, and control circuit means having a pair of input terminals connected to respective ones of said first and second input terminals and four output terminals connected to respective ones of said variable gain amplifier means, said control circuit means being operative in response to said first and second composite signals to produce four auxiliary signals containing program information substantially corresponding to the program information contained in respective ones of said four output signals and to detect the predominant signal or signals instantaneously present in said auxiliary signals and to produce control signals for varying the gain of said variable gain amplifier means so as to increase separation between adjacent loudspeakers.

Claim 9

In apparatus for reproducing on four separate loudspeakers adapted to be arranged around a listener four separate channels of program information contained in first and second composite signals respectively containing first and second component signals representing the program information in first and second ones of said channels, and each containing component signals representing the program information in third and fourth ones of said channels, the combination comprising: first and second input terminals for receiving said first and second composite signals, respectively, a first signal combining network connected to said input terminals and operative to derive from said composite signals four output signals predominantly containing signals representing the information in respective ones of said four channels each accompanied by lower level signals representing information contained in others of said channels, signal coupling means including first, second, third and fourth variable gain amplifier means for receiving and separately coupling a respective one of said four output signals to a respective one of said four loudspeakers, and control circuit means having a pair of input terminals connected to respective ones of said first and second input terminals and four output terminals connected to respective ones of said variable gain amplifier means, said control circuit means being operative in response to said first and second composite signals to produce four auxiliary signals containing program information substantially corresponding to the program information contained in respective ones of said four output signals and to detect the predominant signal or signals instantaneously present in said auxiliary signals and to produce control signals for varying the gain of said variable gain amplifier means so as to increase separation between adjacent loudspeakers.

Claim 10

Apparatus according to claim 5 wherein said control circuit means further comprises, means for continuously comparing the relative amplitudes of said four auxiliary signals and operative to produce control signals for varying the gain of the variable gain amplifier means carrying the output signals instantaneously containing said predominant signal or signals.

Claim 11

Apparatus according to claim 6 wherein said control circuit means includes means for applying said control signals to the variable gain amplifier means and operable to maintain substantially equal the gains of the variable gain amplifier means associated with the first and the fourth of said loudspeakers and to maintain substantially equal the gains of the variable gain amplifier means associated with the second and the third of said loudspeakers.

Claim 12

Apparatus according to claim 6 wherein said comparing means includes means for separately rectifying said four auxiliary signals, and means operative in response to said rectified auxiliary signals to maintain the average value of the sum of said rectified auxiliary signals substantially constant.

Claim 13

Apparatus according to claim 8 wherein said comparing means further includes at least one signal weighting network to which all of said rectified auxiliary signals are applied for producing a signal indicative of which of said output signals contains said instantaneously predominant signal or signals.

Claim 14

Apparatus according to claim 8 wherein said comparing means further includes a single signal weighting network to which all of said rectified auxiliary signals are applied, said signal weighting network being operative to combine two of said rectified auxiliary signals modified by a given weighting factor with the other two of said rectified auxiliary signals modified by a different weighting factor to produce a control signal indicative of which of said two sets of rectified auxiliary signals contains said instantaneously predominant signals or signals, means for applying said control signal in one phase to the control terminals of said first and fourth variable gain amplifier mean, and means for applying said control signal with opposite phase to the control terminals of said second and third variable gain amplifier means.

Claim 15

In apparatus for reproducing on four separate loudspeakers four separate channels of program information contained in first and second composite signals respectively containing first and second component signals representing the program information in first and second ones of said channels, and each containing in-phase portions of a signal representing the program information in a third one of said channels and phase-displaced portions of a signal representing the program information in a fourth one of said channels, the combination comprising: first and second input terminals to which said first and second composite signals are respectively applied, first signal transfer means including a pair of summing networks connected to said input terminals and operative to add and subtract selected components of said composite signals to produce four output signals predominantly containing signals representing the program information in respective ones of said four channels each accompanied by signals representing information contained in its adjacent channels, first, second, third and fourth signal coupling means, each including variable gain amplifier means, for coupling said four output signals to respective ones of four loudspeakers adapted to be arranged around a listener, control circuit means connected to respective ones of said first and second input terminals and including second signal transfer means operative in response to said first and second composite signals to produce four auxiliary signals containing program information substantially corresponding to the program information contained in respective ones of said four output signals, signal comparing means operative to continuously compare the relative amplitudes of said four auxiliary signals and to produce control signals indicative of which signal or signals is instantaneously predominant among said four output signals, and means for coupling said control signals to said variable gain amplifier means and for varying the gain of said variable gain amplifier means so as to increase separation between adjacent loudspeakers.

Claim 16

In apparatus for reproducing on four separate loudspeakers four separate channels of program information contained in first and second composite signals respectively containing first and second component signals representing the program information in first and second ones of said channels, and each containing in-phase portions of a signal representing the program information in a third one of said channels and phase-displaced portions of a signal representing the program information in a fourth one of said channels, the combination comprising: first and second input terminals to which said first and second composite signals are respectively applied, first signal transfer means including a pair of summing networks connected to said input terminals and operative to add and subtract selected components of said composite signals to produce four output signals predominantly containing signals representing the program information in respective ones of said four channels each accompanied by signals representing information contained in its adjacent channels, first, second, third and fourth signal coupling means, each including variable gain amplifier means, for coupling said four output signals to respective ones of four loudspeakers adapted to be arranged around a listener, control circuit means connected to respective ones of said first and second input terminals and including second signal transfer means operative in response to said first and second composite signals to produce four auxiliary signals containing program information substantially corresponding to the program information contained in respective ones of said four output signals, signal comparing means operative to continuously compare the relative amplitudes of said four auxiliary signals and to produce control signals indicative of which signal or signals is instantaneously predominant among said four output signals, and means for coupling said control signals to said variable gain amplifier means and for varying the gain of said variable gain amplifier means so as to increase separation between adjacent loudspeakers.

Claim 17

Apparatus according to claim 11 wherein said control signal coupling means includes a logic circuit operative to momentarily apply a gain-varying control signal to the variable gain amplifier means carrying the output signals corresponding to the instantaneously predominant signal or signals.

Claim 18

Apparatus according to claim 12 wherein said control circuit means further includes first and second signal shaping networks connected between said first and second input terminals and said second signal transfer means, said first and second signal shaping networks having like transmission characteristics approximating the equal loudness contour of the human ear at moderate loudness level and over the audio range of interest and operative to modify said first and second composite signals, respectively, according to said transmission characteristics.

Claim 19

Apparatus according to claim 12 wherein said second signal transfer means includes firSt and second gain control amplifiers, each having an input terminal to which said modified first and second composite signals are respectively applied, a control terminal and an output terminal, means including summing networks connected to the output terminals of said first and second gain control amplifiers for adding and subtracting selected components of said modified composite signals to produce and apply to said signal comparing means said four auxiliary signals, and wherein said signal comparing means includes means for separately rectifying the four auxiliary signals and means for applying a control signal to the control terminal of both said first and second gain control amplifiers of a magnitude to so control their gain as to maintain the average value of the sum of said rectified four auxiliary signals substantially constant.

Claim 20

Apparatus according to claim 14 wherein said logic circuit includes at least one signal weighting network to which said rectified four auxiliary signals are applied.

Claim 21

Apparatus according to claim 14 wherein said logic circuit includes first, second, third and fourth signal weighting networks to each of which all of said rectified four auxiliary signals are applied, each of said weighting networks being operative to combine a respective one of said rectified auxiliary signals modified by a given weighting factor with the other three rectified auxiliary signals modified by a different weighting factor.

Claim 22

Apparatus according to claim 16 wherein said control signal coupling means includes first, second, third and fourth wave-shaping networks respectively connected between said first, second, third and fourth signal weighting networks and respective ones of said variable gain amplifier means.