Abstract: Constant power balance control systems for stereophonic and quadraphonic sound systems are disclosed. Three different embodiments of the invention are disclosed. The first embodiment is a resistive network having a plurality of fixed resistors and a linear potentiometer. The second embodiment is a solid state circuit having four pairs of transistors. The transistors of each transistor pair are chosen to have characteristics such that for the same base-to-emitter voltage, the collector currents of the transistors of each pair satisfy a given ratio. The third embodiment is a combination of the first two embodiments. The third embodiment provides a comprehensive quadraphonic gain and balance control system.

Abstract: Method and apparatus for enhancing the directional content of information recorded or transmitted as four separate channels on a medium having only two independent tracks or channels and subsequently decoded into four signals each of which contains predominantly information pertaining to one of the four original channels but also information pertaining to others, in such a way that the resultant output signals when amplified and presented to four separate loudspeakers give the listener the illusion of four separate sources of sound.