Right- and left-channel signals pass through 1 C4-a and -b buffer amps into active crossover IG5; low frequencies are sent to the IC6-c mixer, and middle and high frequencies are sent to the analog delay lines of 1C1 and 1C2. That output passes through lC6-a and -d to filter high- frequency sample steps. 106-b signals are remixed with low frequencies by 106-c and are sent to final out via IC4-c, and -d buffers. One channel (R) is a variable-delay circuit, using an analog bucket-brigade device and a variable clock frequency. This is compared in amplitude and phase to the L channel (fixed delay).