The trautonium came into being in the late 1920s'/early thirties as a result of a conversation between the composer Paul Hindemith and the engineer Friedrich Trautwein
when they met in the experimental radio station at the Berlin academy of music. Trautwein had first envisaged developing an electronic organ which was refused on financial grounds. Hindemith, being a
viola virtuoso, suggested creating an electronic instrument that could be played in the manner of a stringed instrument. As a result of their collaboration three instruments were constructed for the
performance of Hindemiths' triostucke, with Hindemith, Oskar Sala and Rudolph Schmidt to play each of the parts. As a result of the concerts' success Telefunken wanted to commission a home electronic
instrument based on the design and Oskar Sala who had become enthusiastic about the project, involved himself in the development of a dual manual version with a pedal as a master volume
Telefunken had, in the meantime designed the rather delightfully named thyratron tube, which produced a rich, skewed sawtooth waveform that is quite distinct when viewed on an oscilloscope and becomes almost a square wave when the output is driven hard enough. Trautwein presented Sala with a circuit which had two such valves synchronised with each other as sound generators, the second tube sounding an octave lower. This became the basis of the subharmonic generator, the means by which polyphony could be achieved, soon after Sala was able to produce intervals of a third and fifth by choosing certain tubes. After the second world war a "somewhat crazy circuit" as Sala described it, was designed that enabled the complete realisation of the undertone sequence with a twenty sequence switch. This was extended to 24 divisions on the semiconductor version. It is therefore somewhat ironic that Hindemith had this to say of the subharmonic series-
It seems to me repugnant to good sense to assume a force capable of producing such an inversion ... [The undertone series] can never have for music the same
significance as the overtone series ... This ‘undertone series’ has no influence on the color of the tone, and lacks the other natural advantages of the overtones
series ... (Hindemith, the Craft of Musical Composition, p. 78).
In Sala's own words, " The subharmonic sequence is in itself an interesting occurrence. The tones become lower and lower and therefore have a fuller sound. They don't have anything in common with the sinus tones of the overtone sequence. they always stay polyphonic while being played together and of course respond as sawtooth waves to any kind of formant."
The other main feature of the Trautoniums' sound are the fourfold formant filters, for the time a very sophisticated means of varying the timbre of a waveform. It is essentially four switchable lowpass/bandpass filters with resonance, one for each of the subharmonics. Unlike many filter designs which self oscillate when the resonance is increased, Trautweins' circuit distorts, producing an effect described as trompeten, or a trumpet like brassy texture. The combination of the bandmanual, subharmonic generator and the formant filters made for an instrument of great subtlety, being capable of chameleon like changes in timbre, great expressivenes and polyphony.