This audio mixer circuit schematic we propose here is built around four amplifiers, which are current controlled, all of them incorporated in IC SSM2024, produced by Precision Monolithics Inc. (PMI). To obtain a small offset and a high rejection, the four mixer entries must have a 200 Ω impedance. Those impedances are obtained with resistors R5-R8, which belong to the voltage divider from every audio input.

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