When Teisco, known for its guitars, was acquired by Kawai in the 1970s, the company also began to build keyboards. In 1981, the polyphonic SX-400 came onto the market rather late. It was intended as a competitor to the Roland Jupiter-4, to which it is quite similar. It is four-voice polyphonic or monophonic with the VCOs. The keyboard covers four octaves, and there are also 8 presets and 8 user memory locations.
The SX-400 has four voices, each with a VCO, which can be set independently in the foot position and detuned against each other. The oscillation modes are triangle, sawtooth and square with pulse width modulation. In addition to the VCOs, there is a sub-oscillator that can be used to add sub or noise to the VCO signal or used alone. Quad selects unison, all four oscillators, Dual allows two VCOs to sound simultaneously. Mono means four-voice polyphonic play with one VCO per voice and SOLO means one VCO for one monophonic voice. The filter is a 24 dB lowpass with control options for frequency, resonance and keyboard tracking (KCV). Modulations are performed by LFO I or LFO II or ENV normal or ENV reverse. There are ADSR envelopes for the filter and for the VCA. (Source: Amazona)
