Kawai K5000S additive synthesizer

via this auction

"The K5000S provides 32 sound sources, which is an upper bound on polyphony, and can be quite a bit less, depending on patch complexity. A patch on this synth can combine up to six individual sounds, each of which may be either a PCM (sample) waveform, or an additive waveform. There is also a "multi" or "combo" mode, wherein each combination allows up to four patches to be placed across the keyboard. The "morph mode" you may have heard about is really not a mode, but a way of constructing new additive patches from existing ones (and as with any simple interpolation, the results are usually less interesting than the starting extremes). The provided PCM waveforms would be pretty standard fare, like any other sampled keyboard, except that the modest bank of roughly 123 synth (plus 225 drum) sounds seems to have been chosen carefully to complement the additive sounds. Using these in moderation often seems to balance the additive sounds in just the right way. Additive patches are composed of 64 harmonics, which may be comprised of either low harmonics (1-63) or high harmonics (64-127) of the note fundamental pitch. Additive sounds have low-velocity harmonic amplitude profiles (specifying volume for each harmonic), and high-velocity harmonic amplitude profiles, which are smoothly interpolated between, using various curves, depending on key strike velocity which makes for very smooth velocity-controller changes in timbre. Each harmonic of an additive waveform has its own ADSR envelope (with two attack segments) that can be looped. The K5000S also has a global narrow-band format filter (which I assume really just scales harmonic volumes), that can be used to impart overall coloration to additive sounds, and which can be modulated a variety of ways. Modulation options are pretty good, and include the usual sources (2 x LFO, amplitude envelope, mod wheel, pitch wheel, velocity, mono pressure), and destinations (pitch, volume, filter parameters). You can adjust certain parameters as a function of keyboard position ("key scaling"), though not as well as on some other synths (ex., Kurzweils). The K5000S also has an arpeggiator (and several dedicated knobs), which is reasonably capable, interesting, and useful (I reject the mythology about it being exceptional). There is also a set of 16 knobs, most with assigned synth modulation functionality, but four of which can be set to control various synth parameters (potentially more than one). Finally, there is a global effects section, with offers multiple buses and flexible routing, a complete effects repertoire, and generally very good effect quality. The knob feel is great; the switch feel is mediocre. Switch layout is a bit odd, but you can get used to it. Wandering around the cryptic UI is not fun, but it's not too hard, either. Editing sounds is doable, but quite tedious."