Ray Wilson authored this content while he was actively running MFOS as the founder and resident genius.
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Article by Ray Wilson

Simple Stereo Summing Mixer

Here is a simple stereo summing mixer. The summer op amp outputs are re-inverted so that the outputs are the same phase as the inputs. Use a low noise dual op amp. The caps are ceramic unless noted. The resistors can be 1/4W 5%. The op amp cited in the schematic has a maximum voltage of +/-12V. If you wanted to add gain you could increase the values of the 10K feedback resistors in the output stages. As 20K you would have a gain of 2, as 100K you would have a gain of 10. The formula is simply feedback resistor value divided by input resistor value (10K). AD8022 Information.