Yamaha DX21

Digital programmable algorithm synthesizer

Yamaha DX21 FM synthesizer
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1985 (May)
Initially sold for ¥123,000

The Yamaha DX21 is a 4-operator 8-algorithm synthesizer which can be played in Single, Dual and Split modes.

Another step in making capable synthesis available to the consumer public, the DX21 was released in 1985, improving upon the 4op FM technology first found in the DX9.

699£ got you somewhat what the DX5 was for the original DX7: sound features comparable to having two DX9 engines stacked (with split and layer capabilities), better memory, and a chorus unit. Velocity sensitivity was also available via MIDI input. All in a more compact package, with full MIDI implementation and better overall controls.

Praised by the critics for being a well-thought machine and not just a cut on features of previous models, the price tag made it another success for Yamaha in the 80s.


  • Programmable 4-operator 8-algorithm digital FM tone generator.
  • Independent 5-parameter envelope generator for each operator.
  • 32-voice internal RAM memory.
  • 128 voies programmed into internal ROM.
  • Built-in cassette interface for voice data storage.
  • Single, Dual and Split play modes.
  • 32 performance memories can be programmed with voice combinations and other performance parameters.
  • Built-in chorus effect.
  • 61-key keyboard.
  • The DX21's keyboard itself does not have key velocity, but its tone generator accept key velocity data from an external MIDI keyboard or sequencer.
  • Sustain footswitch, volume foot controller and breath controller inputs.
  • MIDI IN, OUT and THRU terminals.
Yamaha DX21 brochure
Yamaha DX21 brochure
Detail from Electronic Soundmaker & Computer Music, Sep 1985
Detail from Electronic Soundmaker & Computer Music, Sep 1985



61 keys

Sound source

FM tone generator (4 operators x A-B, 8 algorithms)

Simultaneous note output

Polyphonic: single 8 / dual 4 / split 4+4
Monophonic: single 1 / dual 1 / split 1+1

Memory capacity

32 voice internal RAM (alterable)
32 performance internal RAM (alterable)
128 voice ROM (reading only)

Connection terminals and interfaces

Output MIX/A, Output B (mono phone jack)
Output Phones (mono phone jack)
Control jack: foot switch, foot controller
Cassette port
Breath control

909w x 82h x 270d (mm) / 35.8” x 3.2” x 10.6”

8Kg / 17.6lbs


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Yamaha DX21

Yamaha DX21

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Yamaha DX21 FM Synthesizer

Buy used Yamaha DX21 FM Synthesizer
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Yamaha DX21

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