Capable of providing both 8-ohm and constant-voltage outputs (70V and 100V), the 135MA and 160MA are configurable for a variety of uses. Each housed in a half-rack-space chassis, the 135MA is equipped with three inputs and a 35W amplifier output, while the 160MA provides four inputs and a 60W amplifier output. Both models provide priority muting, which can be voice-activated or triggered via an external switch, and are compatible with microphones requiring phantom power.

The front panel of each model comprises a rotary input volume knob and green signal/clip LED for every channel, rotary output volume knob with green (signal) and red (clip) LEDs, recessed pots for bass and treble adjustment, and a power switch with accompanying blue LED. The back panel includes a balanced Phoenix-type mic/line input with threshold control, several line-level RCA input jack pairs (two for 135MA, three for 160MA), a telephone/MOH output with level control, a preamp output, screw-terminal speaker outputs, and a detachable IEC power cord. A DIP switch panel is also provided. Convection-cooled, the new mixer-amplifiers feature protection mechanisms, including current limiting, over-temperature thermal cutout, and DC-fault load protection. The units are also protected against turn-on/turn-off “thumps.”