Roland TR-909

Image:RolandTR-909-front.jpg

Roland TR-909

The Roland TR-909 Rhythm Composer was a partially analog, partially sample-based drum machine built by Roland Corporation in 1984. Being the brainchild of Tadao Kikumoto, the engineer behind the Roland TB-303, it features a 16-step music sequencer and a drum kit that, at that time, aimed for realism and cost-effectiveness. Only around 10000 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 the hype of techno and acid began; more expensive, sample-based drum computers were better at faithfully reproducing real drum sounds, whilst the TR-909 sounded synthetic.

The drum kit contains the following sounds:

• Bass drum
• Snare drum
• Low tom
• Mid tom
• High tom
• Rim shot
• Handclap
• Hi-hat (open or closed, but not at the same time)
• Cymbal (ride or crash, but not at the same time)

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 12-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. A more complex model would also include timbral change, but reproducing this effect using the TR-909's analogue electronics wasn't feasible. It took the industry a while to even offer this effect in sample based drum machines, due to the price of sample memory and the number of samples one would have to take to faithfully reproduce it.

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, punch the buttons 1, 5, 9 and 13 on the bassdrum part, and you have just programmed a 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.

Other manufacturers have made similar devices. These are:

• Jomox XBase 09
• Korg Electribe R (mk I and II)

Not everyone needs the sequencer, so the sounds are also available in convenient 1U high rack units:

• Jomox AirBase 99
• Novation Drumstation

Additionally, an clone of the TR-909's synthsizer parts is available in partial-kit form: 9090. 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.

(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.)

Related links

ReBirth - software synthesizer for PC and Mac that emulates the TR-909 among others

External links

• Samples of the TR-909 are available at Hyperreal.org.
• Vintage Synth Explorer: Roland TR-909