Channel mixer for multi-channel audio systems

A system for simulating reverberation acoustics in an audio signal having first and second input signals comprising:

• first and second reverberation means each for responding to an input signal to provide a similar output signal which persistently repeats beyond the input signal duration, with a decay in signal magnitude with each repetition;
• means for mixing the output signal of said first reverberation means with the second input signal, the output of which is applied as the input signal of the second reverberation means;
• means for mixing the output signal of said second reverberation means with the first input signal, the output of which is applied as the input signal of the first reverberation means, thereby to provide recirculation of signals through the first and second reverberation means in a closed loop;
• means for providing the loop gain of the closed loop less than unity;
• first and second output mixers;
• the first output mixer combining the first input signal, the first reverberation means output signal and the second input signal;
• the second output mixer combining the second input signal, the second reverberation means output signal, and the first input signal;
• first and second phasing means each providing an output reproduction of an input signal applied thereto with the frequency components thereof higher than a selected frequency inverted in phase with respect to frequency components lower than the selected frequency;
• and
• third and fourth output mixers, the outputs of which are respectively applied as the inputs of the second and first phasing means;
• the third output mixer receiving the output of the first output mixer signal and the output of the first phasing means to provide an output representing the combination thereof;
• the fourth output mixer receiving the output of the second output mixer signal and the output of the second phasing means to provide an output representing the combination thereof;
• the outputs of the third and fourth output mixers defining first and second system output signals with simulated reverberation acoustics.

In an audio reproduction system having at least two separate audio signals driving separate front speakers, the improvement of circuitry which creates two additional signals for driving separate rear speakers, said circuitry comprising:

• first and second phasing means each responsive to an input to provide an output in which frequency components in the input signal higher than a selected frequency are inverted in phase with respect to frequency components lower than the selected frequency;
• first and second input mixers receiving on first inputs thereof respective ones of the two separate audio signals and receiving on second inputs thereof the outputs of the first and second phasing means respectively;
• and
• means for applying the outputs of the first and second mixers respectively to the inputs of the second and first phasing means;
• the outputs of the first and second mixers defining signals for driving said separate rear speakers.

A circuit for distributing the information in two input signals into two outputs comprising:

• first means responsive to at least a first one of said two input signals for providing a first output representation thereof in which signals in a predetermined range of frequencies are substantially inverted in phase with respect to other frequencies in said first output representation;
• second means responsive to at least a second one of said two input signals for providing a second output representation in which signals in a predetermined range of frequencies are substantially inverted in phase with respect to other frequencies in said second output representation;
• means for combining said first output representation with said second input signal to provide one of said two outputs;
• means for combining said second output representation into said first input signal to provide the other of said two outputs.