MPX-100

About the MPX-100

Introduced around 1960, the Fisher MPX-100 is a stand-alone FM stereo multiplex decoder that interfaces between an FM mono tuner and a stereo amplifier. It uses five vacuum tubes (6BL8, 12AX7, 12AT7 among others) to decode multiplex FM stereo signals, enabling full stereophonic sound from mono tuners. The unit features the exclusive Fisher Stereo Beacon, an automatic indicator that lights when a multiplex stereo signal is received and turns off for mono broadcasts. It also includes an automatic switching system that senses stereo or mono transmissions and switches modes accordingly, eliminating manual switching. The MPX-100 has input jacks for high and low level tuner outputs and controls for stereo separation and output level, which are adjusted once during installation. It can be mounted in a custom cabinet or with an optional wood cabinet. The unit operates on 105-120V AC, weighs about 7 lbs, and measures approximately 4" high by 12" deep by 4" wide. It was50 in the early 1960s. The MPX-100 was designed to adapt existing FM tuners to the then-new FM stereo multiplex broadcasts, providing a convenient and high-quality stereo upgrade.