Telharmonium II

Cahill, Thaddeus, Washington 1897-1902
Telharmonium II (Dynamophone)
Holyoke (USA) 1903–1906
Ca. 20 m, ca. 200 t
Wood, console with three five-octave manuals (144 keys each, up to 36 keys for one octave), toothed AC generators, motor, water-cooled, ca. 2,000 relay circuits, telephone lines, telephone receiver with horns

The second telharmonium’s 185 hp motor drives 145 toothed AC generators (dynamos) on 8 steel shafts to generate a sinus output voltage. The eight basic notes (C, D, Eb, E, F, G, A, Bb) can each be used to generate 16 harmonics. The resulting sound mix (up to six octaves) is output over two channels (melody and bass accompaniment) and transmitted to telephone receivers with horns via the telephone wires. At least two musicians were needed to operate the two keyboards, the pitch and volume pedals and up to 11 switches per key to mix sounds.