The A-138n 4HP module is a simple four-channel mixer that can be used both to mix control voltages and to mix audio signals. Each of the four inputs has its own attenuator. The output is twofold (mini-multiple.)
The module is the narrow version of the A-138a and has almost identical functions. However, the controls are narrower and smaller, rubberized knobs are used. But the front panel with 4TE is only half as wide as that of the module A-138a . It is therefore primarily intended for applications where space is limited. The functional difference to the A-138a is that the output is not equipped with an attenuator.