Doepfer A-135-4A/B VC Performance Mixer (A + B) [DEMO]

A-135-4A is the main module. It is very similar to module A-138p, but with voltage control for all parameters (except gain). Also the front panels of A-135-4A and A-138p are very similar. The only difference are the additional LEDs which are used to display the magnitudes of all voltage controlled parameters. This is necessary because the positions of the manual controls do not necessarily correspond to the resulting parameter value because these are composed by both the manual controls and the applied external control voltages. Without the LEDs one one be left in the dark in regard to the actual parameter value.

A-135-4B is used to route the 16 external control voltage to the main module A-135-4A.