The instrument
The SK 10 was the first model of the SK synthesiser range, launched in 1979. It was followed in 1980 by the SK 20, SK 30 and SK 50D, and in 1981 by the SK-15, a simplified version of the SK 20. It is an analogue/digital synthesizer with 3 sections: organ, string and poly-synth, each of which can be used independently or combined. The organ features one of Yamaha's early implementations of FM technology in a very limited form, coinciding with the GS-1/2 development platforms that eventually led to the DX series.
Details
The SK 15 can be played over 4 octaves and is fully polyphonic. It has a Leslie simulator, vibrato, attack and sustain, brilliance and a transpose switch for one octave. The organ section offers stop levers from 1‘ to 16’, percussion levers with adjustable decay and controls for sustain, brilliance, decay and tremolo. The strings section has only limited editing options, but an excellent sound. The Poly Synth is a 7-voice polyphonic synthesiser with basic filter, pitch, envelope and portamento controls. It has 1 oscillator per voice. The split keyboard mode combines, for example, a bass sound from the synth section and a lead sound from the organ section.