Roland's D-50 was a keyboard synthesiser, first released in 1987 to great acclaim. It was both popular and influential, and although the D-50 itself is now obsolete, its influence is still felt today. The D-50 was one of the first synthesisers to combine synthetic sound generation with digital samples, using a process which Roland christened 'Linear Arithmetic', a meaningless term commonly abbreviated 'LA'. Simply put, the D-50 could combine traditional electronic tones with short recordings of real-world instruments, a process which is commonplace nowadays but was very clever at the time.

LA synthesis stemmed from the prohibitive cost of computer memory, which meant that the D-50s samples were both short and few in number, one hundred and twenty eight of them taking up a mere half a megabyte. Unable to sample entire pianos, flutes and guitars, Roland merely recorded the first second or so of each instrument, with the synthesiser section filling in the rest. The theory was that people's ears only pay attention to the first second of a sound, a theory which proved surprisingly accurate; the D-50's flute preset, for one, was remarkably lifelike at the time, and is still effective today. In 1987 it sounded like nothing else, certainly not its main competition, Yamaha's dated, twangy FM synthesisers. The D-50 also included built-in reverb and chorus effects, and an EQ section including a high-pass filter, something of a Roland fetish since the Juno-6 of yore. MIDI had, by 1985, taken off, and the D-50 was so equipped. It was 'bi-timbral', in that it could play two patches at once, each with its own MIDI channel. Polyphony varied from 16 notes to four depending on the complexity of the sounds produced, each patch consisting of four voices ('partials', Roland called them), with the D-50 capable of layering two patches. There were six LFOs which could be routed to various different attributes, whilst the envelopes which controlled the filter and amplifier were complex, multi-stage affairs.

The D-50's synthesiser section was based on that of the Roland Alpha Juno range, although simplified. It too used samples, albeit tiny samples of square and sawtooth waves. As the sampling engine was 8-bit it nowadays sounds rather fuzzy in the low-end, and the D-50 is poor at producing punchy, zappy electronic noises. As with the Alpha Juno, the filter's resonance control sounded like nothing else, being warm and incapable of self-oscillating tearing noises. One serious drawback was that the sampled sounds could not be run through the filter at all, although this could be compensated for with the EQ effect. This tended to make many D-50 patches sound the same, and the great success of the machine - it appeared on countless records from 1987 until the early 1990s - means that its most familar sounds sound overfamiliar today. One unusual addition was the ability to ring modulate a sample with a synth tone.

For all the LA theory and the mass of samples the D-50 ended up being used for two things; pads, which are sustained sounds which are used to 'pad out' a recording, and wavering glassy chime noises. The General Midi 'Atmosphere' patch is the essence of D-50 distilled into a single sound, whilst the same basic effect appears prominently in the background of Phil Collins' 'You Can't Hurry Love'. The D-50's most famous pad was 'Soundtrack', a smooth, fifth-separated sweep which became a staple of nature documentaries and ambient records. The D-50 was very good at organ and woodwind noises, plucked strings (such as the pizzicato strings on Enya's 'Orinoco Flow'), electronic pad noises, chimes and crunchy digital loops. The piano samples were very poor, but appear on many early acid house songs in lieu of anything better; Korg obviously took note of this, as their extremely popular Korg M1 had a famous and overused piano noise which appeared on every dance single from 1988 to 1992.

The digital loops were very influential, although subsequent machines by other manufacturers did more with the concept, most notably the Korg Wavestation. Today it is common for synthesisers, both physical and software, to have a number of patches which, when played, produce entire rhythm loops, but in 1985 it was revolutionary. The feature was introduced to the user with a patch called 'Digital Native Dance', a percussive, electronic sequence of crunches and flute sounds which was unusable in music but was clearly the future. The D-50's memory contained a number of similar loops, a last-minute addition which popped up on numerous industrial dance records, and the opening moments of Jean Michel Jarre's 'Revolutions'. It is also worth nothing that the backlit, 32-character, two-line panel LED was capable of displaying 'DigitalNativeDance' without abbreviation, at a time when many synthesisers used two-character LCDs.

Phil Collins, Jean-Michel Jarre, Enya. The D-50 was very popular and appeared on countless records during the period from 1985 to 1989 or so. As a piece of computer equipment it was quickly surpassed, most obviously by the aforementioned Korg M1, which had 16-bit samples and is still used on records today, albeit in sampled form (the organ bassline on Kylie Minogue's 'Can't Get You Out of My Head', for example). As with most other digital synthesisers there is no point in owning one at all, as the sound can be recreated easily by software synthesisers and samplers such as Absynth or Halion. The D-50's keyboard was pleasant to play but unexpectional, with aftertouch being very hard to activate. Roland's curious modulation/pitch-bend semi-joystick was a failed innovation, whilst the interface was not suited for performance. As with its contemporaries, the D-50 required the user to flip through several pages of information, altering values with a slider and + and - buttons, and many users stuck with the preset sounds. To combat this, and in common with Roland's previous analogue synthesisers, Roland sold a separate programming module called the PG-1000. Nonetheless, few of the machine's parameters can be altered in real time, the most crucial omission being the ability to sweep the filter whilst holding down a key.

The D-50 spawned a generation of Roland sound devices. The D-20, D-10 and D-5 were simplified keyboard versions of the D-50, the D-20 making up for its less complex sound and effects with a built-in sequencer and disc drive, whilst the D-550 and D-110 were rackmounted versions of their respected keyboard cousins. Most curious of all was the Roland MT-32, a small angled box which was intended as a computer sound module. Many early PC games have an option for MT-32 sound, and the machine is now the cheapest way to access LA, albeit using the simplified engine of the D-5. A further machine was the D-70, which was a physically imposing keyboard which combined the samples of Roland's later U-20 with the D-50's synthesis engine.

The falling cost of memory and the success of the D-50 led to a generation of synthesisers based around samples, although Yamaha stuck with FM until the early 1990s. Roland followed the D-50 with the U-20, whilst Korg produced the M1, both of which concentrated on giving the user high-quality samples of strings, piano, choirs and so forth. Both were popular machines, although limited in that they could do little more than mix several samples and play them back, rather like a modern-day iteration of the tape-loop Mellotron. The user was limited to those sounds which appeared in the machine's ROM, and until the mid-90s the synth market found itself stuck in a rut. It was not until the advent of virtual analogue machines and software synthesisers that the D-50's legacy was finally put to rest.

On the second hand market the D-50's value is mostly historic. As with all sample-based synthesisers the price has dropped over recent years, as it can be emulated easily. Indeed the D-50 was, essentially, a software synthesiser, albeit running on custom hardware. Whilst analogue synthesisers have knobs and dials to twiddle, and produce timeless electronic sounds, the D-50 does not and cannot. Nonetheless it was an extremely important step in the evolution of modern synthesis, one which has had an enormous influence.

Selected sources
Firtly, my own D-50, and Julian Colbeck's excellent 'Keyfax' books. Secondly,
http://www.cassiel.com/gearhead/d50.html
http://www.sospubs.co.uk/sos/1997_articles/jul97/rolandd50.html
http://www.aracnet.com/~tloepp/support/d50.html