156 x 174 x 155 cm, ca. 200 kg
Wood, keyboard, toothed steel discs, recording magnets, tube amplifier
Twelve sets of steel cogwheels rotate in front of recording magnets with speeds at a ratio of 1:1.059 (corresponding to the frequency ratio between adjoining semitones). One set consists of fourteen cogwheels, but the keyboard covers a range of four octaves (the pitch range from 16’ to 1’ being eight octaves), and thus it is obvious that the remaining cogwheels, thanks to the different shape of their cogs, serve the determination of the timbre. The periodic changes in the magnetic field in the coils generate a tone-frequency alternating current that can be processed using filters or mixed with other tone frequencies. It was this latter method that was used by Laurens Hammond four years after Stelzhammer in the USA.