Sonata features two separate but similarly controlled generators, one for the sound's immediate attack and another for the fundamental tone. Both consist of rich harmonic spectra which are filtered to provide desired overtones. Each possesses an exponential decay envelope for amplitude and another for the filter, as well as a normal ADSR envelope for one or both. The output from these is then fed into a little magic black box (a complex setup of delay devices set relatively for each note) that shapes the sound, emphasizing desired frequencies and providing richer post-filter overtones, similar to the way an instrument's body will influence its sound. There are three global effects: a cross delay, distortion, and a dense reverb meant to accent near-field reflections.
Sonata costs US$35 and a demo version is available.