The output module of the Performance Mixer system sums all conencted input modules and their channels, controls the final volume as well as separately the aux send and aux return levels .

No matter how many A-138p Input modules are connected, the A-138o Performance Mixer Output adds all of them to one stereo sum which is emitted at separate sockets for left and right. Besides this all signals from the channel auxiliaries are summed, available at the Aux Send socket. The Aux Send level can be adjusted. The effect signal has to return into the mixer somewhere of course, which is handled via the Aux Return mono socket. The Aux Return level is adjustable with a potentiometer.

Technical note: Version 2 of the A-138p is equipped with the additional 10 pin connector JP1. It can be used to establish an internal connection to the quad envelope follower A-135-4C. Version 2 can be identified by means of the pc board labelling (A-138p PERFORMANCE MIXER VERSION 2) and the additional pin header JP1. The marker point near JP1 denotes the red wire of the 10 pin ribbon cable that can be used to establish the internal connection between A-138p and A-135-4C. Version 2 of A-138p is manufactured since about June 2017.