The Roland TR-909 Rhythm Composer is a drum machine introduced by the Roland Corporation in 1983. It was the first Roland drum machine to use samples and MIDI. Though it was a commercial failure, the 909 became influential in the development of electronic
The 909 was designed by Tadao Kikumoto, who also designed the Roland TB-303 synthesizer. Chief Roland engineer Makoto Muroi credited the design of the analog and pulse-code modulation voice circuits to "Mr Ou" and its software to "Mr Hoshiai".
Whereas its predecessor, the TR-808, is known for its "boomy" bass, the 909 sounds aggressive and "punchy". It was the first Roland drum machine to use samples (prerecorded sounds), for its crash, ride and hi-hat sounds; other sounds are generated with analog synthesis. As the clap and snare are generated via the same noise source, they produce a phasing effect when played together.
The 909 was also the first Roland drum machine to use MIDI, allowing it to synchronize with other devices,[5] or for sounds to be triggered by an external MIDI controller for wider dynamic range. Older Roland machines can be synchronized via the DIN sync port (a precursor to MIDI).
The 909 features a sequencer that can chain up to 96 patterns into songs of up to 896 measures, and controls including shuffle and flam. It features an improved accent feature, allowing users to accent particular beats or sounds.
Roland changed elements of the 909 during its lifetime, correcting problems and adjusting sounds. Some users modify their machines to match sounds from earlier revisions.