Yamaha DX21 (1985)
The DX21 was Yamaha's mid-1980s attempt to make four-operator FM synthesis affordable. DB Magazine (May 1986, p.55) listed it as an FM digital synthesizer with 61 keys, 128-voice memory, two FM tone generators, four operators, eight algorithms, eight-note polyphonic operation, and built-in MIDI. That reads like a cut-down DX7 for players who couldn't justify the flagship. The same listing priced the DX7 at $2,045 and the DX5 at $3,645, which gives the DX21's market position some context. It doesn't give the DX21's own list price.
The DX21 held 32 voice memories, not the 24 of its cheaper siblings. Yamaha's own DX27 and DX100 manuals both note that when you load a DX21 voice set by cassette, only the first 24 voices fit into those machines' internal memory. Voices 25-32 need the single-voice load function. That 32-voice capacity is one of the few concrete facts about the instrument that survives in manufacturer print.
Beyond that, the record thins out. The DX21's exact original retail price, its full operator parameter set, and its production end date aren't documented in the sources available here, so they stay blank rather than get invented. What is certain: a 61-key, 8-note-polyphonic, 4-operator FM synth with 8 algorithms, 32 voice memories, split/layer capability, and MIDI.
- 61 full-size keys, 8-note polyphony
- 4-operator FM, 8 algorithms, 2 tone generators
- 32 voice memories (per Yamaha DX27/DX100 manual notes)
- Split keyboard and layered sounds; MIDI in/out
- Voice data cassette storage/load
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