GB1363483A - Means for indicating a balance position between the channels of a four channel stereophonic system - Google Patents

Abstract

1363483 Volume controls MATSUSHITA ELECTRIC INDUSTRIAL CO Ltd 23 Sept 1971 [29 Sept 1970] 44497/71 Heading H4J The balanced listening position for a 4- channel stereophonic system is provided by a visual display on an indicator. Fig. 2 shows four amplifier channels. Output 11 supplies a front left speaker (1), Fig. 1 (not shown). Output 15 supplies a front right speaker (2). Output 19 supplies a rear left speaker (3) and output 23 supplies a rear right speaker (4). The two front channels are interconnected by a potentiometer 24 having a variable tapping to earth. This variable tapping is ganged to the earthed variable tapping of a potentiometer 25 interconnecting the two rear channels. The adjustment of the earthed tappings is controlled by a slide knob 31 (Fig. 4) movement of which adjusts the sound output level from left to right. In a similar manner potentiometer 26 interconnects the two left channels and potentiometer 27 interconnects the two right channels. The earthed tappings of potentiometers 26 and 27 are ganged and movement of a slide knob 30 adjusts the sound output level from front to rear. Slide knobs 30 and 31 are secured to rods 33 and 34 respectively which extend through holes in an L-shaped member 35 carrying a lamp 36. Lamp 36 has an opaque cover 38 provided with a hole 39. This provides a light spot which is projected on the underside of a grid-like indicating board (40), Fig. 3 (not shown). The position of the light spot on the grid indicates the balance position in the listening room.