GB1342638A - Sound reproduction system - Google Patents

Abstract

1342638 Four channel stereo system SANSUI ELECTRIC CO Ltd 19 May 1971 [21 May 1970 24 June 1970 16 July 1970 (2) 25 Sept 1970 (2)] 15856/71 Heading H4R Left, L, and right, R, stereo signals are combined to form four composite signals L-#R, L + #R, R + #L, and R-#L, where # is a value between 0 and 1. The signals L-#R and R-#L are phase shifted to have substantially the same phase, and the signals are applied to respective loud-speakers arranged at the corners of a quadrilateral defining a listening area. R + #L and L + #R are fed to the respective right and left front speakers while R-#L and L- #R are fed to the respective right and left rear speakers. As described with respect to Fig. 3 the four signals are derived by feeding R and L signals to respective phase splitters 33 and 34 the outputs from which are fed to a potential divider 35-40, from which taps 41 to 44 supply the front signals. The phase shifting can be provided by the circuit of Fig. 5 which provides + 90 degree phase shift to the R-#L signal applied at terminal 51, and -90 degree phase shift to the signal L - #R applied at terminal 54, so that the signals are substantially in phase and the stereo image is properly located. This arrangement provides a varying phase shift between the front and rear signals and to eliminate this, phase shift circuits can be provided in all signal channels, Fig. 7 (not shown), so as to provide equality of phase in the two front signals and the two rear signals, and 90 degree phase shift of the front signals relative to the rear signal.