The instrument
The SK synthesisers from Yamaha are the successors to the SS 30 Stringmachine. They offer various analogue sound generators. The smallest model is the SK 10 from 1979, which only has an organ, string and brass section. The SK SK 20, released in 1980, offers similar features, but the simple brass section of its predecessor was replaced by a polyphonic synthesiser. The SK 30 added a monophonic lead synth section, the SK 50 D a second keyboard and a bass section. Apart from the strings, all polyphonic sections of the SK series offer two to three preset sounds in addition to manual registration.
Details
The SK 20 is played over 5 octaves. Various split combinations are also available. The sounds can be mixed continuously in the master section and can also be detuned against each other in some cases. The organ section is modelled on classic Hammond organs. There are nine faders for the foot positions (16′, 8′, 51/3′, 4′, 22/3′, 2′, 1′), two further faders and a DECAY control for the percussion register, a brilliance control, two envelope switches (decay and sustain) and a sustain fader. The polysynth has an oscillator with six waveforms in different foot positions. A low-pass filter with resonance works as a low-pass filter with 12 dB attenuation per octave or as a 6 dB bandpass. It is also equipped with an ADSR envelope and an LFO with a sine waveform. The synths with strings can be operated in two octaves and share decay and release VCA envelopes with the polysynth. Vibrato, tremolo and ensemble effects are also available. (Source: Keyboards)