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| Number | Title | Issue Date |
| 4251685 | Reproduction of sound In a sound reproduction system which enables the listener to distinguish between signals from in front and behind as well as signals on the left and the right, only two independent transmission channels are employed. The contributions to the signals in th... | 02/17/1981 |
| 4236039 | Signal matrixing for directional reproduction of sound Multidirectional sound signals are optimally matrixed to increase the psychoacoustic directional fidelity as compared with prior systems. Four (or more) azimuthally spaced loudspeakers are fed from two transmission channels with very satisfactory directio... | 11/25/1980 |
| 4072821 | Microphone system for producing signals for quadraphonic reproduction A system including a compact array of special purpose microphones and an encoder, especially suited for use with surround-sound sources, for producing two composite output signals equivalent to those required by the "SQ" quadraphonic system to establish t... | 02/07/1978 |
| 4006313 | Transmitting and reproducing system having improved noise reduction characteristics for quadraphonic audio information signals A transmitting and reproducing system includes an encoder for selectively combining at least four signals for transmission along two channels. At least three of the signals are combined in a predetermined amplitude and phase relationship to form a first u... | 02/01/1977 |
| 3970788 | Monaural and stereo compatible multidirectional sound matrixing Multidirectional source signals which are encoded in two monaural and stereo-compatible transmission channels with predetermined amplitude and phase relations indicative of source directions and adapted to be decoded for formation of more than two loudspe... | 07/20/1976 |
| 3937885 | Control circuit for a matrixed four channel audio reproducing system A gain controlled audio amplifier for each channel which includes a differential to single ended converter fed by a differential amplifier, the common emitters of which are coupled to balance and volume control circuitry for controlling the amount of curr... | 02/10/1976 |
| 3932706 | Signal synthesizing system adaptable for discrete four-channel sound reproducing system and matrix four-channel sound reproducing system The invention discloses a system for synthesizing first and second recording or transmission signals adaptable for both of a discrete four-channel stereo sound reproducing system and a matrix four-channel stereo sound reproducing system. The first recordi... | 01/13/1976 |
