Polarizing CV-Mixer

This is my prototype of Bipolar CV Mixer. Nothing really special here but very practical module in modular setup. Four inputs with level pots. One Master output with attenuator pot, one straight output and one inverted output. A nice LED-driver with a spear op-amp (one TL074). LED's show if the mixed voltage is bipolar or unipolar. I must source a dual-color led with two parallel LED's in same case. Switch selects if the input potentiometers behave as attenuators or polarisers. When polarising you can either add (cw side) or subtract (ccw side) voltages from the master-mix.