The Telharmonium (also known as the Dynamophone) was an early electrical organ, developed by Thaddeus Cahill circa 1896 and patented in 1897. The electrical signal from the Telharmonium was transmitted over wires; it was heard on the receiving end by means of "horn" speakers.
Like the later Hammond organ, the Telharmonium used tonewheels to generate musical sounds as electrical signals by additive synthesis. It is considered to be the first synthetic instrument due to its ability to generate sounds electromechanically because the sound is produced by moving parts rather than electronic oscillators.
Cahill built three versions: The Mark I version weighed 7 tons. The Mark II version weighed almost 200 tons, as did the Mark III. Each was a considerable advancement over the features of its predecessor. A small number of performances in front of a live audience were given in addition to the telephone transmissions. Performances in New York City (some at "Telharmonic Hall", 39th and Broadway) were well received by the public in 1906, and the performer would sit at a console (see picture) to control the instrument. The actual mechanism of the instrument itself was so large it occupied an entire room — wires from the controlling console were fed discreetly through holes in the floor of an auditorium into the instrument room itself, which was housed in the basement beneath the concert hall.
The Telharmonium foreshadowed modern electronic musical equipment in a number of ways. For instance, its sound output came in the form of connecting ordinary telephone receivers to large paper cones — a primitive form of loudspeaker. Indeed, Cahill was noted for saying that electromagnetic diaphragms were the most preferable means of outputting its distinctive sound.
The Telharmonium's demise came for a number of reasons. Its immense size, weight and power consumption (this being in an age before vacuum tubes had been invented) caused obvious problems. In addition, problems began to arise when telephone broadcasts of Telharmonium music were subject to crosstalk and unsuspecting telephone users would be interrupted by strange electronic music. By 1912, interest in this revolutionary instrument had changed, and Cahill's company was declared not successful in 1914.
Cahill died in 1934; his younger brother retained the Mark I for decades, but was unable to interest anyone in it. This was the last version to be scrapped, in 1962.
Telharmonium tones are "clear and pure" — referring to the electronic sine wave tones it was capable of producing. However, it was not restricted to such simple sounds. Each tonewheel of the instrument corresponded to a single note, and, to broaden its possibilities, Cahill added several extra tonewheels to add harmonics to each note. This, combined with organ-like stops and multiple keyboards (the Telharmonium was polyphonic), as well as a number of foot pedals, meant that every sound could be sculpted and reshaped — the instrument was noted for its ability to reproduce the sounds of common orchestral woodwind instruments such as the flute, bassoon, clarinet, and also the cello. The Telharmonium needed 670 kilowatts of power and had 153 keys that allowed it to work properly.