First MIDI synths, Hallelujah, Beatmania drelectro1 ♦ December 26, 2011 ♦ 2 Comments 1982 Sequential Circuits releases the (6P) Prophet-600 , the first synthesizer with built-in MIDI . MIDI is first demonstrated at the January 1983 Winter NAMM by Sequential owner Dave Smith . For the first 15 years, pro-quality synths had