Home-brewed Theremins ... and other strange devices

Theremin Geschichte / History

The technical Fundamentals of Theremin's Aetherwaves-Music.
By Dipl.-Ing.  A. L i o n, Berlin 1927

Originally published in: 'Zeitschrift für Instrumentenbau Jahrgang 48. Nr.5 1.12.1927  S.198-199, Paul de Wit, Leipzig'

English transcription by

Transcription Note:

The article [9] 'Die technischen Grundlagen von Theremin's Aetherwellen-Musik' of A. Lion was originally published in the German instrument-manufacturers magazine 'Zeitschrift für Instrumentenbau Jahrgang 48. Nr.5 1.12.1927  S.198-199, Paul de Wit, Leipzig' in December 1927, shortly after Theremin had presented his instrument in various cities of Germany, so in Munich on the 12th of November 1927 at the ODEON concert-hall, Odeonsplatz 3 (today: 'Bavarian Ministry of the Interior'). The program [43] of this presentation and concert was originally not included in the article and  is presented for completion. It is assumed, that the program of Theremin's performances was similar every time it was presented. It has to be noted that according to the program flyer two (!) Theremin-Instruments were played, one by Julius Goldberg and the other by Leon Theremin himself. From the drawing attached to the article, the instrument played by Theremin was the early one including the little switch box on the left, referred to as tone-color register, as can be seen on the well known vintage pictures. From today’s point of view and knowledge, the article is partially incorrect. Therefore, some comments are added which are enclosed in {brackets}.

Additional information of early electronic theremin circuitry can be found in the following historical German publications:

[7] Ing. Joachim Winckelmann: “Das Theremin-Musikgerät – Aetherwellen-Musik … ein neues Reich der Töne!”, DRB46 Deutsche Radio-Bücherei, Deutsch-Literarisches Institut J. Scheider, Berlin-Tempelhof, 1932  

[8] Ing. Joachim Winckelmann: “Das neue Universal-Schaltungsbuch – Die 120 modernsten und besten Schaltungen!”, DRB25 4. Auflage, Deutsche Radio-Bücherei, Deutsch-Literarisches Institut J. Scheider, Berlin-Tempelhof, 1932

The presentations of the 'Music out of the Air' by professor Leo Theremin of Leningrad have gathered extraordinary sensation some weeks ago. One immediately noticed, that this instrument can not be considered a mindless device, subtly utilizing technical advances, nor a talking-machine and  neither a artificial instrument, whose technical refinement creates tonal sounds, resembling e.g. a violin and a cello; instead one could see that this 'Aetherwaves-Musical-Instrument' was capable to produce entirely new sound-characters of remarkably richness, partially resembling known instruments, to some extent outclassing them by far, at which the performing artist, not different to a string- or percussion-instrument, controles by the musical will, incarnated in his hands, pitch, volume, softness of tone - shortly everything representing the artistic performance. Only the generation of sound-material, in a manner of speaking -  which has to be manipulated by the performing artist, takes place by novel technical means, namely basically using the currently most subtle and sensitive – the radio-tube.

Theremin's instrument is an apparatus, connected to a speaker, exhibiting a rod- and a loop-shaped antenna made of strong brass wire. When the right hand is brought near the rod-antenna in the air, sounds of extraordinary tone-beauty and richness, whose pitch is determined by the distance of the hand to the antenna, are generated. By increasing the distance to or approaching the loop-shaped antenna, the volume is controlled accordingly. The sound-generation is thus electrical, but the performance is artistic as with every other musical instrument. The non-technician, the musician as well as the ordinary person, seems to stand in front of a marvel, when Theremin actually catches such perfect sounds out of the air, one hears the strangest speculations of the formation of this sounds. A marvel, or something supernatural, multitudinous people actually believe in, is of course not at hand; instead only a ingenious utilization of technical means for musical purposes. The fundamentals of Theremin's musical instrument shall therefore shortly described in the following lines and one will see, that this is not a marvel but 'only' a combination of a number of good ideas.

A sound perception is based always on somehow generated vibrations. At Theremin's invention, the oscillator is the radio-tube - nowadays known to everybody, radiating electrical waves, thus oscillations. From the well-known disturbances of radio-transmissions, every radio-listener is already familiar with the fact that a antenna not only receives waves but also transmits them {refer  to regeneration-receiver}. One can now substantially change the 'capacity' of an antenna by moving an object, e.g. the hand, near it and hence by such movements a pitch influencing vibration-change of the oscillator, thus the tube, is provoked, this means that a certain position of the 'playing' hand in relation to the antenna corresponds to a specific pitch. This is the principle, all far from that is the task of certain circuits and the coupling of multiple of those resonant circuits, allowing to generate flawless tones and overtones. Shape and size of the antenna and the distance of the hand from it in space, corresponding to specific pitches, thus the 'spatial grips', can be determined by rules within certain limits and can, if one wishes, be adapted to match the grips of the violin or cello. If one utilizes two or three antennas, one can play two or three voices simultaneously using one hand {this is very questionable and is probably an interpretation of the author, not aware of the actual functions of Theremin's circuits; according to patents, simultaneous voices have been achieved by Theremin using several fixed oscillators – or one fixed oscillator with several resonant circuits to extract the RF (Radio Frequency) harmonics, which are mixed to the variable oscillator-signal, producing corresponding beat frequencies, controlled by a single pitch-antenna}. To learn the grips is said to be even easier than to learn playing string-instruments. The sound affecting the ear, thus the conversion of electrical to acoustical vibrations, takes place as known from radio-broadcasts by the speaker, which as a result significantly dominates the sound-character and has to be superior in therms of acoustics {known today as broadband speaker [23]}.

The volume is controlled by change of the current-strength, which serves to produce the oscillations within the sound-generator {this is somewhat incorrect; the anode (plate) or filament current of the audio-amplifier/limiter tube is controlled}. There are various contemplable means, e.g. as the simplest the variation of an interconnected resistor using a pedal {this resistor may not have controled the speaker or speaker amplifier directly in Leon Theremin's original instruments}. However, the change of the filament heating – every radio-amateur is already familiar with this term – can be accomplished with the help of the interaction of a additional 'high frequency resonant circuit' of another tube as well, which is controlled in the same manner as the sound producing one {the pitch oscillator tube, connected to the pitch antenna}, namely by approaching or removing a hand, the left, to/from the related {volume control} antenna. The one hand controls the 'music-antenna' {pitch-antenna}, the other the 'volume-antenna'. One can arrange yet another equally manipulated special 'switch-on antenna' for switching on or off the sound, but therefore simpler means exist.

The change in tone-color, thus the harmonics- and sub-harmonics {!} related to the fundamental sound, can be achieved by utilization of different tubes {tubes with different characteristics, refer to Theremin's patents}, arranged within the instrument, or by other known components of radio-technology like capacitors, choke-coils and so forth, which are switched on while playing, by means of lateral 'registers' {refer to pictures of Theremin's early instruments}. The importance of the speaker for the color of sound was already mentioned. The beauty of sound is enhanced, similar to string instruments, by a slight vibration of the music playing hand, whereby new possibilities of influencing the tonal-character are accomplished {frequency- and amplitude overtone sound-spectrum modulation [41]}. At Theremin's instrument, not other means are applied than those already known from radio {but in abnormal ways}. In general, a 2 volts rechargeable {lead-} battery for filament-heating and an anode (plate-) voltage of 180 volts is used {a standard in those days}.

Theremin's presentations, which are also remarkably approbatory received by the music-world, have given an idea of the many possibilities of such musical instruments. The tight tuning of a pitch by electrical means outclasses all other mechanical means of adjustments {at fixed pitched instruments}. Intervals can be met with an accuracy other instruments not possess. Theremin actually did build other similar instruments, solely based on electrical adjustment of intervals. The presented 'Thereminophon' {= Theremin-Keyboard ?} allows the generation of every high- and low pitched sound by alteration and switching in the different sound-creating elements. Because the fineness of adjustment by electrical means knows no borders, and the strangest sound-colors and the largest volumes can be achieved, for music – and in particular for the orchestral-music of the future, entirely new means have been created by those instruments.

The sounds of the instruments built according to Theremin's chain of thoughts, do follow all prescribed peculiarities and details of the score, from the percussion-instrument to almost the human voice, in a remarkably way. It has to be especially emphasized, that the most essential of those instruments is not the application of electricity conduced to art, thus switching soulless notes – the entirely mechanical mastering of the sound-material, but rather the much closer connection of the sound-material to the individuality of the performing artist, mastering the sound without interposition of mechanical or machinery means by his hands. No other instruments achieve that; all are tangibly burdened – only the air, in which this instrument is 'played', is immaterial and virtually weightless. Therefrom its unsurpassable expressiveness, its ability of following the line of the musician's thought more instantaneously and precisely than the known musical instruments.

This instrument is no mindless robot: the artistic work nowhere depends more directly on the ability and musicality of the artist like at it. 

Dipl.-Ing. A. L i o n ,  Berlin.