The Yamaha DX-21 is a 61-key synth, based on FM synthesis, from the mid 80s.

It is 8-voice polyphonic, and while it sounds very close to other DX’s, it was a consumer keyboard, without velocity or aftertouch sensitivity.

If you’ve used the Yamaha DX21, leave a comment with your thoughts on it!

Features:

• Performance Memory – 32 Performance Memory System, programmable with data on play modes, key shift, detune and pitch bend. It will automatically recall these real-time performance parameters as well as the voice or combination of voices.
• FM Digital Synthesis – Instead of VCOs, VCAs, and VCFs, the DX21 uses “operators” (a digital sine wave generator combined with an envelope generator) to produce sound that can be used alone or in combination with other operators.
• Voice Memories – 32MB RAM (Random Access Memory) voice memories, organized in two banks of 16 voice selector keys.
• Pre-Programmed Voices Built In – 128 pre-programmed voices permanently stored in internal ROM (Read Only) memory. Organized into groups of 8, these voices can be loaded individually or in groups into the 32-voice RAM memory.
• Three Ways to Play – Two FM Tone Generators allow voices to be selected three ways: Single, Dual, or Split play modes.
• MIDI Functions – A broad range of MIDI functions make the DX21 exceptionally useful in virtually any MIDI system application.
• Cassette Storage – A built in cassette interface allows an unlimited number of voices to be programmed and stored on cassette tape. Cassette voices can then be loaded into RAM memory when needed.

Specifications:

• Keyboard 61 keys, C1 – C6
• Sound Source FM Tone Generators: 4 operators x 2 (A,B), 8 Algorithms
• Polyphonic 8 notes (Single), 4 notes (Dual), 4 + 4 notes (Split)
• Monophonic 1 note (Single, Dual), 1 + 1 note (Split)
• Internal Memory 128 ROM voice memory, 32 RAM voice memory, 32 RAM performance memory
• Controls Pitch Bend Wheel, Modulation Wheel, Volume, Balance, Data Entry
• Displays LCD (16 characters x 2 lines)
• Connecting Terminals Output Mix/A, Output B, Phones, Cassette
• Control Terminals Footswitch (Sustain, Portamento), Foot Controller (Volume), MIDI (In, Out, Thru)
• Dimensions 909(w) x 82(h) x 270(d) mm, 35.8(w) x 3.2(h) x 10.6(d) inches
• Weight 8 kg (17.6 lbs)
• United States and Canada 120 V, 50/60 Hz
• General Models 220 – 240 V, 50 Hz
• Power Consumption 7 W

Resources:

• burp.nl has a information on the Yamaha DX21, Yamaha DX27 & Yamaha DX100.
• Yamaha’s DX21 page
• DX21 Sound samples
• Soundquest DX21 Editor/Librarian
• Video demo via alphacode909