Electronic Circuit mixer with 3 line inputs and 3 mic inputs

A simple mixer with 3 line inputs and 3 mic inputs using commonly available parts.
The mixer circuit above has 3 line inputs and 3 mic inputs.
The mic inputs are suitable for low impedance 200-1000R dynamic microphones. An ECM or condenser mic can also be used, but must have bias applied via a series resistor. As with any mixer circuit, a slight loss is always introduced. The final summing amplifier has a gain of 2 or 6dB to overcome this. The Input line level should be around 200mV RMS. The Pinouts for LM741, LF351 ,TL071 and NE5534 are shown below. Pinouts for other IC's can be found on the