EML Polybox for sale. This one's orange. Fully serviced by professionals and working great, no typical surprises most people expect when they buy vintage gear from other sellers.
Back in the day, most synthesizers were monophonic - that is they could play only 1 note at a time. EML realized this limitation and came up with the Polybox. This rare little box has built in oscillators which track the pitch of an incoming audio signal really well - even following vibrato and portamento successfully. Take any monophonic synthesizer audio output, patch it into this synth and play the Polybox's keys along with the mono melody to convert it to chords. Or lock the chord memory so it follows your melody automatically with a set chord that's transposed along with the melody's pitch. Or play its internal oscillators as its own sound. This is a very cool, unique and extremely useful tool! It's rare too. And pretty dang cute! Works well with various synths, including the Electrocomp line from EML.