Roland D-50 Digital LA Synthesizer

The Roland D-50 is a 16-voice synthesizer with a 61-key touch-sensitive keyboard. It was the first synthesizer to use sample-based digital subtractive synthesis—referred to by Roland as LA synthesis or linear arithmetic synthesis—for sound generation. To develop its warm sound, Roland provided the development engineers with two sound designers. For complex sound editing, the Roland PG-1000 external programmer (1987) can be connected. The D-550 is a rack-mount variant with nearly 450 adjustable parameters. More affordable variants were introduced in 1988 with the D-10, the D-20, and the D-110 rack module. In 1990, the D-50 was replaced by the D-70.

The D-50 is one of the best-selling synthesizers alongside the Yamaha DX7 (1983) and the Korg M1 (1988). It has been used by musicians such as Prince, Sting, Michael Jackson, Enya, Jean-Michel Jarre, Tangerine Dream, and the Pet Shop Boys.

The sound generation of the D-50 can be divided into the sample section and the synthesis section. It combines an attack sample with the square and sawtooth waveforms of digital oscillators, which provide the sound body (sustain). The samples were recorded with a resolution of 16 bits. The first 47 waveforms are pure attack samples, the next group are loops containing only the upper range of the overtone spectrum and the last 24 samples are sample loops with incorrect loop points. The PCM samples cannot be filtered. The pulse width can be modulated using velocity, aftertouch and LFO. The raw oscillation forms pass through a resonant low-pass filter (Time Variant Filter) with a multi-stage envelope, which can be influenced by an LFO or the envelope responsible for the filter, and then through the amplifier. There are 16 synthesiser voices (tones) consisting of two partials. A partial is a sound chain consisting of an oscillator or sample, including filter, envelopes and LFO. Up to four partials can be combined to form a patch, with seven interconnection options, as well as ring modulation. The D-50 has chorus, reverb and echo effects as well as a 2-band equaliser.