Stereo separation control

Claim 1

Circuitry for use over the audio frequency range and responsive to first and second stereo audio input signals, L in and R in , for producing at least one of first and second audio output signals, L out and R out , said circuitry comprising stereo signal mixing circuitry including a first variable control means having a parameter, K, capable of varying over a range -1≦K≦+1 second variable control means having a parameter, K', capable of varying over a range -1≦K'≦+1; said first variable control means being responsive to said first and second input signals for selectively controlling the proportions of said first input signal and said second input signal to produce said first output signal such that the relationship between said first and second input signals and said first output signal is proportional to (L in )(1-K)+(K)(L in +R in )/(M) for 0≦K≦+1, and to (L in )(1+K)-(K)(L in -R in )/(N) for -1≦K≦0; said second variable control means being responsive to said first and second input signals for selectively controlling the proportions of said second input signal and said first input signal such that the relationship between said first and second input signals and said second output signal is proportional to (R in )(1-K')+(K')(L in +R in )/(M) for 0≦K'≦+1, and to (R in )(1+K)-(K') (R in -L in )/(N) for -1≦K'≦0, where 1/M is an instantaneous sum factor the value of which is adjustable and 1/N is an instantaneous difference factor the value of which is adjustable.