Hammond, Laurens, Chicago 1935
Lender: Eboardmuseum, Klagenfurt (Austria)
Model: Hammond E
148 x 75 x 118 cm, ca. 220 kg
Wood, keyboard, pedals, synchronous motor, serrated metal tone wheels, permanent magnet, cogwheel drive, tube amplifier

The cogwheel generator contains 91 tone wheels with a varying number of cogs driven by a synchronous motor, the speed of which depends on the network frequency. The speeds needed to generate the 12 semitones of each octave are obtained by means of a cogwheel drive with different ratios. Drawbars are used to adjust the intensity of the partials in order to configure the sound. The chorus effect is generated by a second tone generator slightly out of tune. The rigid mechanical settings of the frequency generation mean that the organ itself cannot become out of tune.