The Polyphon 'Hermann Just' is the first coin-insertion model of automated performance machines that was produced by Polyphon. The disc mechanism enabled the shift of the music box into more commercial surroundings.
The beginning of the 20th century marked the end of the age of large cylinder instruments. The newly developed disc-type music box was mainly made by 'The Big Three': Polyphon, Symphonion and Regina.
Gustave Brachhausen and Paul Riessner founded Polyphon Musikwerke around 1890 and went on to produce various instruments with a wide array of disc sizes and different cabinet styles.sources
The music played by this type of music box, is programmed by punching perforations into a disc. The disc causes a music comb to be plucked by means of intervening levers. As with most music boxes of this kind, the discs change automatically in the ‘Hermann Just’ which holds 12 discs. The desired selection can be made by placing the sliding indicator on the appropriate tune card on the front of the machine.sources