He and his wife died in 1942 of food poisoning during the famine caused by the Nazi-Fascist occupation during WWII.
[b] They were custom-built for him in Piraeus by the luthier Kyriakos Peismatoglou, and differed in one important respect from other plucked long-necked lutes in use in Greece at this time, in that they were not fretted according to the equal temperament division of the octave into twelve identical semitones.
Instead they[c] had sixteen frets to the octave, which permitted, among other things, the playing of microtonally different intervals such as the so-called three-quarter tone, and the neutral third, at certain positions on the fretboard.
It is to be heard very clearly playing an introductory taxim to the song Diamánto alaniára (Διαμάντω αλανιάρα), during which is to be heard the exclamation Γιά σου Γιοβάν Τσαούς με το ταμπούρη σού (approx: Hi there Yovan Tsaous with your tambouri).
It appears that Tsaous was almost alone in playing these particular instruments; the fact that they did not produce equally tempered intervals made them problematic in ensemble work, and this is readily audible in his recordings, which have a unique sound.