Electrical – Audio Mixing Circuit


So I'm working on a audio mixing circuit, and based on some research I settled on the following circuit:

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My question is whether or not the circuit will work as intended. I feel that the process of mixing the signals in such a way seems overly simplistic and I might be missing something obvious. Any suggestions would be great. Thanks

Best Answer

It is overly simplistic and may not always work as intended.

Specifically, if either of the inputs is (a) fed from an appreciable source impedance and (b) drives a second output, that second output will hear crosstalk from the other inputs. It should be obvious why, and you can easily calculate the level of crosstalk when you know all the impedances.

So it's not something you'd want in a recording studio.

(If neither of those conditions holds, then this circuit will actually work, provided the input resistors are high enough to prevent the inputs from damage by being connected together)

The classic mixing configuration is a "virtual earth" mixer, based around an inverting amplifier configuration (e.g. using an opamp, NOT a power amp like an LM386). This holds the mixing node (the opamp's inverting input) at ground potential so there is no crosstalk between inputs.