These photos are courtesy of Pasquale Rosa. This VC mixer was added to the CEMS after 1969.
It is constructed as a module with four VCA and one mixer PCBs. Edge connectors are used for front panel wiring.
The label simply says Volt Con. Mixer
This photo shows one of the four channel PCBs.
This photo shows the barrier strip used for power distribution.
This partial photo shows sthe mixer PCB.