History [from the Wikipedia]
The theremin was originally the product of Russian government-sponsored research into proximity sensors. The instrument was invented by a young Russian physicist named Lev Sergeivich Termen (known in the West as Léon Theremin) in 1919 after the outbreak of the Russian civil war. After positive reviews at Moscow electronics conferences, Theremin demonstrated the device to Bolshevik leader Vladimir Lenin. Lenin was so impressed with the device that he began taking lessons in playing it, commissioned six hundred of the instruments for distribution throughout the Soviet Union, and sent Theremin on a trip around the world to demonstrate the latest Soviet technology and the invention of electronic music. After a lengthy tour of Europe, during which time he demonstrated his invention to packed houses, Theremin found his way to the United States, where he patented his invention in 1928 (US1661058 ). Subsequently, Theremin granted commercial production rights to RCA.
Although the RCA Thereminvox, released immediately following the Stock Market Crash of 1929, was not a commercial success, it fascinated audiences in America and abroad. Clara Rockmore, a well-known thereminist, toured to wide acclaim, performing a classical repertoire in concert halls around the United States, often sharing the bill with Paul Robeson. In 1938, Theremin left the United States, though the circumstances related to his departure are in dispute. Many accounts claim he was taken from his New York City apartment by KGB agents, taken back to the Soviet Union and made to work in a sharashka laboratory prison camp at Magadan, Siberia. He reappeared 30 years later. In his 2000 biography of the inventor, Theremin: Ether Music and Espionage, Albert Glinsky suggested the Russian had fled to escape crushing personal debts, and was then caught up in Stalin's political purges. In any case, Theremin did not return to the United States until 1991.
After a flurry of interest in America following the end of the Second World War, the theremin soon fell into disuse with serious musicians, mainly because newer electronic instruments were introduced that were easier to play. However, a niche interest in the theremin persisted, mostly among electronics enthusiasts and kit-building hobbyists. One of these electronics enthusiasts, Robert Moog, began building theremins in the 1950s, while he was a high-school student. Moog subsequently published a number of articles about building theremins, and sold theremin kits which were intended to be assembled by the customer. Moog credited what he learned from the experience as leading directly to his groundbreaking synthesizer, the Moog.
Since the release of the film "Theremin: An Electronic Odyssey" in 1994, the instrument has enjoyed a resurgence in interest and has become more widely used by contemporary musicians. Even though many theremin sounds can be approximated on many modern synthesizers, some musicians continue to appreciate the expressiveness, novelty and uniqueness of using an actual theremin. The film itself has garnered excellent reviews.
The theremin is unique among musical instruments in that it is played without physical contact. The musician (occasionally referred to as a thereminist) stands in front of the instrument and moves his or her hands in the proximity of two metal antennas. The distance from one antenna determines frequency (pitch), and the distance from the other controls amplitude (volume). Most frequently, the right hand controls the pitch and the left controls the volume, although some performers reverse this arrangement. Some low cost theremins use a conventional, knob operated volume control and have only the pitch antenna.
The theremin uses the heterodyne principle to generate an audio signal. The instrument's circuitry includes two radio frequency oscillators. One oscillator operates at a fixed frequency. The frequency of the other oscillator is controlled by the performer's distance from the pitch control antenna. The performer's hand acts as the grounded plate (the performer's body being the connection to ground) of a variable capacitor in an L-C (inductance-capacitance) circuit. The difference between the frequencies of the two oscillators at each moment allows the creation of a difference tone in the audio frequency range, resulting in audio signals that are amplified and sent to a loudspeaker.
To control volume, the performer's other hand acts as the grounded plate of another variable capacitor. In this case, the capacitor detunes another oscillator, which affects the amplifier circuit. The distance between the performer's hand and the volume control antenna determines the capacitor's value, which regulates the theremin's volume.
Easy to learn but notoriously difficult to master, theremin performance presents two challenges: reliable control of the instrument's pitch with no guidance (no keys, valves, frets, or finger-board positions), and minimizing undesired portamento that is inherent in the instrument's microtonal design.
Pitch control is challenging because, like a violin or trombone, a theremin generates tones of any pitch throughout its entire range, including those that lie between the conventional notes. In the case of some string instruments, the range is divided along the strings by use of length divisions (e.g., frets on a guitar). By contrast, in the case of the theremin, the entire range of pitches is controlled by the distance of the performer's hand or fingers to the pitch antenna in mid-air. Precise control of manual position coupled with an excellent sense of pitch is required, since the electromagnetic field around the antenna tends to change slowly over time, resulting in changing positions of individual pitches.
Also, the theremin's continuous range of pitches lends itself to glissando playing, which can be inappropriate to the piece being performed. Skilled performers, through rapid and exact hand movements, minimize undesired portamento and glissando to play individual notes and can even achieve staccato effects. Small and rapid movements of the hands can create tremolo or vibrato effects.
Although pitch is governed primarily by the distance of the performer's hand to the pitch antenna, most precision thereminists augment their playing techniques with a system called "aerial fingering", largely devised by Clara Rockmore and subsequently adapted by Leon Theremin and his protege, Lydia Kavina. It employs specific hand and finger positions to alter slightly the amount of capacitance relative to the pitch antenna to produce small changes in tone quickly and in a manner that can be reliably reproduced.
Equally important in theremin articulation is the use of the volume control antenna. Unlike touched instruments, where simply halting play or damping a resonator silences the instrument, the thereminist must "play the rests, as well as the notes", as Ms. Rockmore observes. Although volume technique is less developed than pitch technique, some thereminists have worked to extend it, especially Pamelia Kurstin's "walking bass" technique.
Skilled players who overcome these challenges by a precisely controlled combination of movements can achieve complex and expressive performances, and thus realize a theremin's potential.
Some thereminists in the avant-garde openly rebel against developing any formalized technique, viewing it as imposing traditional limitations on an instrument that is inherently free form. These players choose to develop their own highly personalized techniques. The question of the relative value of formal technique versus free form performances is hotly debated among thereminists. Theremin artist Anthony Ptak uses antenna interference in live performance.
Recent versions of the theremin has been functionally updated: the Moog Ethervox, while functionally still a theremin, can also be used as a MIDI controller, and as such, the artist is able to control any MIDI-compatible synthesizer with it, using the theremin's continuous pitch to drive modern synths.