Roland TR-909

The TR-909 was a partially analog, partially sample-based drum machine built by Roland Corporation in 1984. Being the brainchild of Tadao Kikumoto, also the engineer behind the TB-303, it features a 16-step music sequencer and a drum kit that, at that time, aimed for as much realism as was possible.

Like the TB-303, the mark of realism was missed by a few miles due to technical constraints, and this showed when the machines were blown out for low prices before the hype of techno and acid began; sample-based drum computers were better in 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
• Hihat (open or closed, but not at the same time)
• Cymbal (ride or crash, but not at the same time)

All drums except for the hihats and cymbals are synthetically generated; there is an oscillator circuit with a dedicated filter and envelope curve. The hihats and cymbals are 6-bit samples, compressed and combined with a volume envelope curve 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 part called "accent" - this is a primitive means to humanize the drumbeat. If we were to design a model of a drummer and a kit, and we simplify the model, the loudness of the sound depends on the velocity the drummer hits the percussion with. A human drummer can emphasize certain notes by playing these louder, and the accent parameter provides a means to boost a particular step. A more complex model would also include timbral change, but it took the industry a while to offer this 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 is due to the 16-step sequencer - in this day and age it might look primitive, not allowing subtle grooves, and 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 programed a 4-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 the so-called groovebox - self-contained compact synthesizer workstations with a rudimentary keyboard and a pattern-based sequencer, aimed at electronic music, using sample-based sound generation and a number of realtime controls.

Other manufacturers have made similar devices. These are:

• Jomox XBase 09
• Elektron Machinedrum
• 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

The grooveboxes are not included in the list since they also contain more than just drums, even though they might have copied the principle of the 16-step sequencer.

External links

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