Sound signal converting apparatus for use in a four channel stereophonic reproduction system

Claim 2

In a sound signal-converting apparatus including matrix circuit means for reproducing first, second, third and fourth four-channel output signals by additively combining two channel input signals in first and second ratios to produce said first and second output signals, respectively, and subtractively combining said two channel input signals in third and fourth ratios to produce said third and fourth output signals, respectively, the improvement wherein said matrix circuit means includes means for varying each of said first, second, third, and fourth mixing ratios from a first ratio when both two channel input signals are at one frequency to a second higher ratio when both two channel input signals are at a second higher frequency.

Claim 3

A sound signal converting apparatus for reproducing four output signals from first and second channel signals comprising: means connected to receive the first and second channel signals for producing sum and difference signals; first level varying means connected to receive the difference signals for varying the level thereof according to the frequency thereof; second level varying means connected to receive the sum signal for varying the level thereof according to the frequency thereof; means for additively combining the sum signal of first and second channel signals and the output signal of said first level varying means to produce a first output signal; means for subtractively combining the sum signal of first and second channel signals and the output signal of said first level varying means to produce a second output signal; means for additively combining the difference signal of first and second channel signals and the output signal of said second level varying means to produce a third output signal; and means for subtractively combining the difference signal of first and second channel signals and the output signal of said second level varying means to produce a fourth output signal.

Claim 4

A sound signal converting apparatus for reproducing four output signals from first and second channel signals comprising: means connected to receive the first and second channel signals for producing sum and difference signals; first level varying means connected to receive the difference signals for varying the level thereof according to the frequency thereof; second level varying means connected to receive the sum signal for varying the level thereof according to the frequency thereof; means for additively combining the sum signal of first and second channel signals and the output signal of said first level varying means to produce a first output signal; means for subtractively combining the sum signal of first and second channel signals and the output signal of said first level varying means to produce a second output signal; means for additively combining the difference signal of first and second channel signals and the output signal of said second level varying means to produce a third output signal; and means for subtractively combining the difference signal of first and second channel signals and the output signal of said second level varying means to produce a fourth output signal.

Claim 5

A sound signal converting apparatus according to claim 2 wherein said first and second level varying means are operative to attenuate the levels of the difference and sum signals, respectively, as the frequencies thereof fall.

Claim 6

A sound signal converting apparatus according to claim 3 wherein each of said first and second level varying means includes a capacitor.

Claim 7

A sound signal-converting apparatus for reproducing on four output channels four-channel signals from first and second channel signals, comprising: first means for additively combining said second channel signal with said first channel signal in a predetermined ratio of said second channel signal to said first channel signal for channel signals of a medium frequency, in a larger ratio than said predetermined ratio for channel signals of a lower frequency and in a smaller ratio than said predetermined ratio for channel signals of a higher frequency to produce a first output signal; second means for additively combining said first channel signal with sadi second channel signal said a predetermined ratio of said first channel signal to said second channel signal for channel signals of the medium frequency, in a larger ratio than said predetermined ratio for channel signals of the lower frequency and in a smaller ratio than said predetermined ratio for channel signals of the higher frequency to produce a second output signal; third means for subtractively combining said second channel signal with said first channel signal in a predetermined ratio of said second channel signal to said first channel signal for channel signals of a medium frequency, in a larger ratio than said predetermined ratio for channel signals of the lower frequency and in a smaller ratio than said predetermined ratio for channel signals of the higher frequency to produce a third output signal; and fourth means for subtractively combining said first channel signal with said second channel signal in a predetermined ratio of said first channel signal to said second channel signal for channel signals of the medium frequency, in a larger ratio than said predetermined ratio for channel signals of the lower frequency and in a smaller ratio than said predetermined ratio for channel signals of the higher frequency to produce a fourth output signal.

Claim 8

A sound signal-converting apparatus for reproducing on four output channels four-channel signals from first and second channel signals, comprising: first means for additively combining said second channel signal with said first channel signal in a predetermined ratio of said second channel signal to said first channel signal for channel signals of a medium frequency, in a larger ratio than said predetermined ratio for channel signals of a lower frequency and in a smaller ratio than said predetermined ratio for channel signals of a higher frequency to produce a first output signal; second means for additively combining said first channel signal with sadi second channel signal said a predetermined ratio of said first channel signal to said second channel signal for channel signals of the medium frequency, in a larger ratio than said predetermined ratio for channel signals of the lower frequency and in a smaller ratio than said predetermined ratio for channel signals of the higher frequency to produce a second output signal; third means for subtractively combining said second channel signal with said first channel signal in a predetermined ratio of said second channel signal to said first channel signal for channel signals of a medium frequency, in a larger ratio than said predetermined ratio for channel signals of the lower frequency and in a smaller ratio than said predetermined ratio for channel signals of the higher frequency to produce a third output signal; and fourth means for subtractively combining said first channel signal with said second channel signal in a predetermined ratio of said first channel signal to said second channel signal for channel signals of the medium frequency, in a larger ratio than said predetermined ratio for channel signals of the lower frequency and in a smaller ratio than said predetermined ratio for channel signals of the higher frequency to produce a fourth output signal.

Claim 9

A sound signal-converting apparatus according to claim 1 wherein said first means includes an impedance circuit including reactive impedance elements for coupling said first channel signal to the first output channel, and a resistor for coupling said second channel signal to the first output channel; said second means includes an impedance circuit including reactive impedance elements for coupling said second channel signal to the second output channel, and a resistor for coupling said first channel signal to the second output channel; said third means includes an impedance circuit including reactive impedance elements for coupling said first channel signal to the third output channel, and a resistor for coupling said second channel signal of opposite polarity to the third output channel; and said fourth means includes an impedance circuit including reactive impedance elements for coupling said second channel signal to the fourth output channel, and a resistor for coupling said first channel signal of opposite polarity to the fourth output channel.

Claim 10

A sound signal-converting apparatus according to claim 6 wherein said impedance circuits include a parallel arrangement including a first resistor, a first capacitor and a serial circuit of a second resistor and a second capacitor, respectively.

Claim 11

A sound signal-converting apparatus according to claim 5 further including means for producing a sum signal by additively combining said first and second channel signals and for producing first and second difference signals having the opposite polarities by subtractively combining said first and second channel signals; wherein said first means includes means for coupling said sum signal to the first output channel and means for coupling said first difference signal to the first output channel, the latter means including level-varying means for increasingly attenuating the level of said first difference signal as its frequency falls; said second means includes means for coupling said sum signal to the second output channel and means for coupling said second difference signal to the second output channel, said latter means including level-varying means for increasingly attenuating the level of said second difference signal as its frequency falls; said third means comprises means for coupling said first difference signal to the third output signal and means for coupling said sum signal to the third output channel, said latter means including level-varying means for increasingly attenuating the level of said sum signal as its frequency falls; and said fourth means has means for coupling said second difference signal to the fourth output channel and means for coupling said sum signal to the fourth output channel, said latter means including level-varying means for increasingly attenuating the level of said sum signal as its frequency falls.

Claim 12

A sound signal-converting apparatus according to claim 8 wherein said level-varying means include a capacitor, respectively.