I really like this organ. It had always been classified as a kind of synth, but in fact it is essentially an organ since it had only one waveform (which is even not saw but simply square) in its two oscillators. It had even no filter, no modulation, and no envelope! It was nothing else than two sources of sound providing nothing else than a square form. Each sound source was mounted as traditional divide-down circuit as on all the organs and string synths or this epoch, and both had just an own vibrato as modulation, that's all. The only possibility to vary the sound was just to detune one source on an adjustable amount... and to use the pitch-bend level at the left of the panel during the monophonic play with the right hand. It was simple a two octave range keyboard, not a three octave range (the grey part of the keyboard wasn't really a third octave, it was a special 12 keys keyboard placed here atleft as a second keyboard of only one octave... or to repeat easier for the left hand some of the buttons of the panel to vary the richness of the sound in harmonics as with the 7 white buttons of the left part of the panel and the five sliders at the center!)
It was published to be used as a very cheap lead keyboard beside the string machines at an epoch where very few musicians could afford the very expensive real synths of Moog and ARP. In fact it was developed to be something able to compete a bit against the ARP Pro Soloist (reproduced with nice sounds in the ProSolo VST) which was itself also a sort of ultra-simple synth of the poor... but with the prestige of the mark ARP. AM Music Technology made a very nice emulation of the ProSolo VST) and Elektrostudio made a very nice emulation of the Davolisynth.
Dave Sinclair was a virtuoso of the Davolisynth in his rock band Caravan (that he founded in 1968) at the years of 1972-75 (far less after), and he played it a bit again for the fun of the public in the years 1978-79 in a few concerts when he was keyboardist of the band Camel.