Multivox MX8100

“Up for auction today is a very nice old Multivox MX-8100 CV/Gate synthesizer keyboard/sequencer, made most probably in the late 1970s by Multivox Corporation of America out of Hauppauge, NY. It features 37 keys, the ability to record and playback up to 4 sequences of notes, both Exponential (Hz/Volt, Moog, etc.) and Linear (Oct/Volt, Korg, etc.) output, and multiple tunable parameters. And pretty blinking lights.

There’s a dearth of information out there on this unit, and I’ve never seen a manual for it, so here’s a description of the features as best as I understand them:

On the left front of the board is the sequencer section. You can select any one of four memory banks, play and record a sequence, then play it back by punching one of the four buttons. I don’t know how exactly how many notes a sequence will hold, the amount of RAM in this machine has got to be miniscule, but it’s enough to set up some pretty decent loops. (There’s a handy red “bar graph” to the right of the sequencer banks that will tell you how much memory you have left. But, be aware that the sequences are NOT saved when the keyboard is powered down.)

Going on to the right, you have controls for setting your sequence to one time or endless, as well as for setting the tempo of the playback. You can shut Newkey Trigger on and off and adjust the Portamento rate.

The rightmost set of controls on the board is a lot of fun, allowing you to adjust the Slope, Frequency, and Range of the CV output, for both Exponential and Linear CV. I don’t know the scientific definition of those terms, but I know they allow one to mangle the sound in interesting ways.

The back of the unit has 1/4″ Input/Output jacks for Exponential and Linear CV, as well as Input/Output jacks for both positive and negative Gate signals.

There are also 1/4″ jacks for “Remote”, “Foot Switch”, and “External Restart”. Exactly what those do I don’t know. My guess would be that these were designed to be chained together, but that’s only a guess. There’s also a pair of mysterious “Data Ports”. They look a bit like midi jacks, but they’re not. Was it possible to control this unit from some early computer? Your guess is as good as mine.

Speaking of midi, this keyboard doesn’t do midi, it’s strictly control voltage. Note also that this keyboard does not produce any sound on its own, it’s strictly a controller. Just wanted to make that clear 🙂

This particular unit has aged remarkably well, it’s clean and corrosion-free and has only a few minor scratches on the decals. They keys are slightly yellow but work very well, as does everything else I’ve been able to test .”
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