[NOTE: the following article originally appeared in Gyrofrog № 2, October 1992]
The theremin is perhaps one of the most unusual musical instruments to have emerged in the twentieth century. Invented by Leon Theremin around 1920, the theremin is the result of experiments with radio and vacuum-tube technology, making it one of the very first electronic musical instruments (its only significant predecessor being Thaddeus Cahill's gargantuan telharmonium, which debuted around the turn of the century). Rather than being plucked, struck, bowed, or keyed like other musical instruments, the theremin is played by changing the proximity of one's hands to two antennae, one controlling pitch and the other controlling volume.
The theremin operates using a principle of radio operation called heterodyning. Heterodyning is a method of combining two frequencies well above the range of human hearing (or, more specifically, in the radio frequency range) to produce a third frequency that is equal to the difference between the two radio frequencies and lies within the range of human hearing (i.e. approximately 20 Hz to 20,000 Hz). In the case of the theremin, a beat frequency oscillator combines the output of two radio-frequency oscillators -- one operating at a fixed frequency of 170,000 Hz, the other with a variable frequency between 168,000 and 170,000 Hz as determined by the proximity of the musician's hand to the pitch antenna. The difference of the fixed and variable radio frequencies results in an audible beat frequency between 0 and 2,000 Hz. Thus, the theremin player changes the pitch of the instrument by moving his or her hand closer to or farther from the pitch antenna. The theremin's volume is controlled similarly, by moving the other hand closer to or farther from a second antenna.
The general public became aware of the theremin during the 1920s and 1930s, when Leon Theremin toured Europe and then moved to New York with his instrument. Violinist Clara Rockmore became the first musician to really master the instrument, having overcome the fact that since the theremin is played by moving one's hands through the air, there is no visible or tactile reference for determining pitch, as there are with the frets of a guitar or the keys on a piano. On the other hand, this gives the theremin player the ability to produce a glissando, or glide, between pitches, as with a trombone, slide whistle, or slide guitar. A C.D. titled The Art of the Theremin features Clara Rockmore, with piano accompaniment by her sister, Nadia Reisenberg, performing theremin renditions of music by Rachmaninoff, Stravinsky, Tchaikovsky, and other composers. The theremin heard on this disc was built by Leon Theremin himself, and produces a tone which eerily resembles a cross between a woman's voice and a violin.
Leon Theremin was approached by composers Henry Cowell and Edgard Varese to design instruments specifically for their respective compositions. Cowell (for whom Fred Frith's old band, Henry Cow, was named) worked with Theremin on the development of the rhythmicon, which used the theremin's heterodyning principle but was controlled by a piano-style keyboard and capable of producing complex rhythms. By the time Cowell's composition finally premiered, however, the rhythmicon was no longer functional and had to be simulated with a computer. Theremin unsuccessfully tried to invent a new instrument for Edgard Varese's Equatorial; Varese instead used the French-designed ondes martenot. This instrument also operated using the heterodyning principle, but was controlled by moving a finger ring attached to a sliding loop of wire, with a diagram of a piano keyboard printed underneath for pitch reference (an ondes martenot may be heard in the soundtrack of the Alfred Hitchcock film Spellbound). Leon Theremin also invented a special dance platform called the terpsitone which also doubled as a musical instrument, using the principles of the dancer's movements.
R.C.A. marketed its own version of the theremin during the 1930s, and Bob Moog, inventor of the Moog Synthesizer, made his living in the early 1960s by selling do-it-yourself theremin kits of his own design. In fact, the theremin used in the Beach Boys' "Good Vibrations" may have been one of Moog's instruments. Another rock group, appropriately named Lothar and the Hand People, prominently featured the theremin in their music.
For anyone who is so inclined (and, of course, possesses a certain amount of knowledge of electronics), it is possible to construct a theremin based on schematic diagrams, which are available from at least three different sources. The liner notes from The Art of the Theremin include the schematic diagram of the R.C.A. theremin. While this model uses vacuum tubes, someone I know claims that the tubes used in the circuit are still available. Unfortunately, the values of the different resistors, capacitors, and inductors are not specified. The book Electronic Music Production (2nd edition) by Alan Douglas features a schematic diagram of an updated, transistorized theremin, but the values of these transistors are not given. The schematics in Experimenting with Electronic Music by Robert Brown and Mark Olsen are more complete, although the directions for fine-tuning the circuit are a bit unclear.
As of 1987, when The Art of the Theremin was released, Leon Theremin was conducting research in electronic music and acoustics at the University of Moscow.
Addendum (1996): In November 1993 (about one year after I first wrote this), Leon Theremin died in Moscow at the age of 97. A few years earlier, Theremin was allowed to visit the United States, during which time he did a guest lecture at Stanford University. Around the time of Theremin's death, Todd Rundgren released a CD titled No World Order, the cover of which shows Rundgren playing what appears to be an R.C.A. theremin. Fishbone and The Jon Spencer Blues Explosion are both known to have taken theremins along during concert tours. More recently, a documentary titled Theremin: a Musical Odyssey, directed by Steven Martin, has been released to wide acclaim (it is available on video). The film features interviews with Robert Moog, Clara Rockmore, Todd Rundgren, Brian Wilson, and Leon Theremin himself. Theremin kits are once again on the market, and are available from Paia Electronics as well as Robert Moog.
- Brown, Robert and Mark Olsen. Experimenting with Electronic Music. Blue Ridge Summit, PA: TAB Books, No. 666, 1975.
- Douglas, Alan. Electronic Music Production. Second edition. Blue Ridge Summit, PA: TAB Books, No. 1418, 1982.
- Holmes, Thomas B. Electronic and Experimental Music. New York: Scribners, 1985.
- Moog, Robert. Liner notes. The Art of the Theremin by Clara Rockmore. Delos International D/CD 1014: 1987.
- Rockmore, Clara. The Art of the Theremin. Delos International D/CD 1014: 1987.