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TR-909 Front Panel
|Synthesis type||Analog Subtractive and
Digital Sample-based Subtractive
|Memory||96 Patterns, 8 Songs|
|Effects||Individual level, tuning, attack,
decay, and tone controls for some
|Keyboard||16 Pattern Keys|
|External control||MIDI In/Out & DIN Sync In|
The Roland TR-909 Rhythm Composer is a partially analog, partially sample-based, drum machine introduced by the Japanese Roland Corporation in 1983. The brainchild of Tadao Kikumoto, the engineer behind the Roland TB-303, it features a 16-step step sequencer and a drum kit that aimed for realism and cost-effectiveness. It is fully programmable, and like its predecessor, the TR-808, it can store entire songs with multiple sections, as opposed to simply storing patterns. It was the first MIDI-equipped drum machine. Around 10,000 units were produced.
As with the TB-303, the realism of the TR-909 was severely limited by technical constraints, and this showed when the machines were released at relatively low prices before its rise in popularity, coinciding with the beginnings of techno and acid. More expensive, sample-based drum computers were better at faithfully reproducing real drum sounds, while the TR-909 sounded synthetic.
The drum kit contains the following sounds:
- Bass drum
- Snare drum
- Low tom
- Mid tom
- High tom
- Rim shot
- Hi-hat (open or closed, but not at the same time)
- Ride cymbal
- Crash cymbal
All drums except for the hi-hats and cymbals are synthetically generated; there is an oscillator circuit with a dedicated filter and envelope curve. The hi-hats and cymbals are 6-bit samples, compressed and combined with a volume envelope curve (and tuning) to allow slight modification. Thanks to the analog circuitry, various aspects of the drum sound can be modified (pitch, attack, decay).
There is also a feature called "accent"—a primitive means of humanizing the drumbeat. In a simplified model of a drummer and a kit, the loudness of the sound created would basically depend on the velocity at which the drummer hits a given part of the kit. A human drummer can emphasize certain notes by playing them louder, and the accent parameter provides a means to boost a particular step.
Part of the charm of the TR-909 comes from its 16-step sequencer — today it might look primitive, not allowing subtle grooves and being limited in variety with only 16 steps, while a more lively, complicated drum pattern might need much more than that. On the other hand, acid techno music is usually simple compared to the styles that might require more than 16 steps to a bar. For example, punching the buttons 1, 5, 9 and 13 on the bass drum part would create a simple "four to the floor" beat.
While the sequencer is running, a light runs from step 1 to step 16.
The TR-909 has several editing modes: pattern editing where one focuses solely on the 16 steps, and track editing, which allows for chaining various patterns in a row. Because it has MIDI, it's also possible to control other instruments with the sequencer.
This machine and its unique sequencer (both Roland and other manufacturers used either a grid-based sequencer, showing the dots on an LCD, or another method that did not display the pattern at all) were the basis for so-called grooveboxes — self-contained compact synthesizer workstations with rudimentary keyboards and pattern-based sequencers, aimed at creators of electronic music, using sample-based sound generation and a number of realtime controls.
Notable users and songs 
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- 808 State
- Aphex Twin
- Atari Teenage Riot
- Benny Benassi
- The Berzerker
- Boys Noize
- Chemical Brothers
- Dennis Ferrer - has requested to one day be buried with his 909
- Phil Collins - "Sussudio", "Take Me Home"
- Daft Punk and their Revolution 909 song
- Fatboy Slim
- The Glove
- Gorillaz- Plastic Beach
- Gus Gus
- Inner City
- Kerri Chandler
- LCD Soundsystem
- Oliver Lieb
- Jeff Mills
- Bobby Orlando & Divine
- The Prodigy
- Vince Watson
- Skinny Puppy
Other manufacturers have made similar devices:
(Grooveboxes are not included in this list as they contain more than just drums, though they may have copied the principle of the 16-step sequencer.)
- JoMoX is a German company in Berlin. Its first Drum Machine was called the "Xbase 09";
- they also made a rack version of it called the "Airbase 09". It was discontinued in the late 1990s. Jomox currently makes a newer model called the Xbase 999.
Additionally, a clone of the TR-909's synthesizer parts is available in partial-kit form. This kit includes the main board and audio out PCBs, sample ROMs, and PIC Microcontroller (for handling MIDI) but requires a builder to order their own components and design their own enclosure.
- ReBirth RB-338 - software synthesizer that emulates the TB-303, TR-808, and TR-909. Available for Windows and Mac (OS 9 or older), IPhone and iPad.
- D16 Drumazon - software drum machine that emulates the TR-909.
- AudioRealism ADM - software drum machine that emulates the TR-909 as well as the TR-808 and TR-606 drum machines.
- Martin Russ. Sound synthesis and sampling. p. 66.
- Hsieh, Christine. "Electronic Musician: Tadao Kikumoto". Retrieved 2010-10-02.
- Vince Watson (June 29, 2012). "Vince Watson Closing 909 Festival 2012 with 909 Solo (Full Version)". Youtube. Retrieved 11 January 2013.
- Radiohead (December 31, 2007). "Radiohead - Videotape (Scotch Mist Version)". YouTube. Retrieved 19 January 2012.
- Justin Kleinfeld (April 1, 2007). "Skinny Puppy gets respect". Electronic Musician Magazine. Retrieved 2 August 2010. Text " Remix Interviews cEvin Key and Nivek Ogre of Skinny Puppy " ignored (help)
- 9090 Introspectiv
- TR-909 samples
- Vintage Synth Explorer: Roland TR-909
- Roland 909 emulator with source code
- DGenR8 Virtual Analog Drum Synthesizer - A TR-909 inspired drum synthesizer using analog modeling
- Hobnox Audiotool - Flash music applet featuring simulations of the TR-808, TR-909, TB-303, and various stomp effects
- TR-909 samples in .wav format
- Rebirth Museum - Online museum and download page for the ReBirth RB-338
- DIY 909 clone