Rare 50s Passive Broadcast Summing Mixer – MX/18M/378

Rare Passive Broadcast Summing Mixer – MX/18M/378 – Belgian Radio, ca. 1960

Collector’s piece – also perfect for vintage analog studios

This passive 4-in / 2-out summing mixer was originally built for Belgian public broadcasting. Based on its mechanical design and component quality, it likely dates from the late 1950s or early 1960s. The internal build features four discrete, hand-wired attenuation stages made with high-grade resistors and massive brass terminals — similar in concept to the legendary Eckmiller W88 faders. All wiring is meticulously laid out by hand.

The mixer works passively, with four inputs routed to a dual mono output. It’s ideal for collectors of historical broadcast gear — but also fully functional for today’s audio workflows. Whether used as a minimalist summing solution in an all-analog setup or simply displayed in a vintage control room, this unit is a reminder of an engineering standard rarely seen today.

Build quality like this no longer exists. These kinds of mechanical rotary attenuators — with this level of material use — are virtually extinct, even in military-grade equipment. No surface-mount tech, no ribbon cables. Just brass, solder and craftsmanship.

Condition:

Very good for its age. Fully original. Tested and working, but sold as collectors item - no warranty

Specs (approximate):

– 4x Inputs

– Dual Output (parallel)

– Fully passive signal path

– Handmade rotary attenuators with solid brass terminals

– Solid enclosure with engraved front panel

A unique item with unmistakable character. Sold as a collector’s item – but absolutely usable as a passive 4-in-1 (or 4-in-2) summing device.