How a Theremin Works

In the early 1920s, physicist Léon Theremin was doing research on proximity sensors for the Russian government. He was trying to develop something like a land-based sonar device using an electromagnetic field to detect objects that entered a certain zone. Instead, Theremin came up with a musical instrument: his namesake, the theremin.

He demonstrated his creation to Russian leader Vladimir Lenin, who was said to have "adored" the new instrument [source: Beckerman]. Lenin sent Theremin on a world tour to show off the new technology, and Theremin delighted audiences throughout Europe with his "ether-wave" concerts. Theremin eventually found his way to the United States, where he patented the "Thereminvox" in 1928.

Hailed as the world's first electronic instrument, avant-garde composers like Joseph Schillenger immediately recognized the potential of Theremin's device. In 1929, Schillenger premiered his "First Airphonic Suite" in New York City, and his theremin soloist, Léon Theremin, became the talk of the town. RCA quickly snapped up manufacturing rights to the Thereminvox and hatched an advertising campaign designed to sell a theremin for every living room in the country [source: Beckerman].

Although RCA's "Theremin" was a commercial failure, their 1930s-era device is still considered by many to be the holy grail of theremins [source: Michael Rogers]. In a time before electric guitars and synthesizers, the theremin amazed audiences with its seemingly magical capabilities. Virtuoso performances by theremin masters like Clara Rockmore and Lucie Rosen ensured a loyal cult following for the instrument.

In 1954, before he began work on the synthesizer that bears his name, Robert Moog's company, the R.A. Moog Company, began producing theremins. From there, the instrument's following grew even larger, and it became associated with eerie wails in science fiction films [source: Theremin.info]. Today, the theremin still enjoys a dedicated cult following and appears occasionally in all kinds of music, from symphony concertos to the music of Tom Waits.

For an instrument that only sold 485 original units, the theremin has enjoyed a storied history, especially in film. Here are just a few programs that have featured Léon Theremin’s unique invention [source: Theremin.info]:

With no complicated chords or fingerings, at first glance, the theremin seems like it should be a cinch to play. So why do many enthusiasts consider it the world's most difficult instrument? Find out on the next page.

Way back in the early 1920s, when Léon Theremin worked at the Physico-Technical Institute in St. Petersburg, Russia, he noticed that when he moved his body in or out of an electromagnetic field produced by a radio frequency oscillating circuit, he changed its frequency [source: Harrison]. The human body has a certain natural capacitance (the ability to hold an electrical charge). What Theremin observed when he used his body to disrupt the oscillator’s electromagnetic field was the effect of this capacitance. Maybe because he was a musician and a cellist by hobby, Theremin began pondering how to exploit capacitance to create a new musical instrument.

In a 1989 interview with Olivia Mattis, Theremin said, "I conceived of an instrument that would create sound without using any mechanical energy, like the conductor of an orchestra" [source: Mattis]. What Theremin dreamed up was an electronic instrument with two primary circuits: a pitch circuit and a volume circuit. The pitch circuit used two tuned (radio frequency) oscillators: a fixed oscillator and a variable oscillator. The fixed oscillator generated waves at a static frequency. The variable oscillator was capable of producing a range of frequencies and was connected to a vertical antenna. Through a process called heterodyning, signals from the fixed and variable oscillators were mixed together. The frequency of one oscillator was subtracted from the other. The difference was amplified and, finally, output as an audible musical tone.

The second circuit (the volume circuit) controlled the level of the tone generated by the pitch circuit. Much like in the pitch circuit, it used an oscillator connected to an antenna. Disrupting the electromagnetic field around this antenna raises or lowered the volume of the music tone generated by the pitch circuit.

Today, hackers and musical tinkerers of all kinds use these same principles to create all manner of Theremins and Theremin-like devices. Since a simple fluttering of fingers is all it takes to make noise on a Theremin, it seems like the Theremin would be a cinch to play. Find out why many enthusiasts consider the Theremin the world's most difficult instrument in the next section.

Many people have played the theremin, but only a few have mastered it. Below, we'll list three of the most important players in theremin history.

Clara Rockmore: Probably the world's most celebrated thereminist, Clara Rockmore developed an intricate fingering technique for theremin that allowed for precise pitch control.

Lucie Bigelow Rosen: A student of Léon Theremin, Lucie Rosen kept a detailed notebook on theremin design and construction [source: Thereminvox.com]. Her theremin, designed by the inventor himself, is still on view at her former home, Caramoor.

Samuel Hoffman: Hoffman lent his theremin skills to numerous television shows and movie soundtracks including "It Came From Outer Space," "The Day the Earth Stood Still" and "The Delicate Delinquent" [source: Theremin.info].

With only two antennae to manipulate, the theremin seems like it would be a breeze to play. Looks, however, can be deceiving. In the hands of a master, the theremin can sing with the precision, vibrato and depth of a seasoned mezzo-soprano. When operated by a novice, on the other hand, it produces little more than earsplitting blats and squawks.

A theremin works by generating electromagnetic fields around two antennae. A straight, vertical antenna controls pitch; A horizontal, looped antenna controls volume. A masterful player makes very small, precise finger and hand movements in the field around the vertical antenna to change pitch and create melodies. ("You have to play with butterfly wings," virtuoso thereminist Clara Rockmore was quoted as saying [source: Wakin].) In addition to controlling pitch, a theremin player must also control volume. She accomplishes this by hovering her hand (usually the left) over the instrument's horizontal antenna. Exaggerated jerking and flailing movements are counterproductive. An experienced theremin master appears to be dancing with her hands, drawing a song from thin air, like magic.

The secret to great Theremin playing lies in perfect pitch control. A great player must possess a good ear, fine muscle control and ample coordination. The first time a new player approaches a theremin, his performance is more likely to sound drunken and atonal than distinguished or adept. Many hours of practice, however, help a player develop the hearing and muscle memory necessary for keeping a melody in tune. Once he's mastered those basics, he can progress to adding vibrato and dynamics to his playing. A real theremin master can make an instrument soar with the fortissimo of Pavarotti or fade to the most delicate of whispers. If you want to learn even more about the art of theremin playing, take a look at our article How to Play a Theremin.

Theremins with fixed volume controls may be somewhat easier to play since they only have one antenna. Curious about the different types of Theremins available? The next page has you covered.

Relatively simply circuitry coupled with a certain cult novelty makes the theremin one of the most hackable instruments out there. From vintage, vacuum tube devices to musical toys made out of LEGO bricks, there are theremins and theremin kits to suit every fancy.

Probably the most popular version on the market today is the Moog Etherwave Theremin. The Standard Moog Etherwave features pitch and volume antennae, as well as rotary pots for controlling waveform and sensitivity. The Moog Etherwave Plus contains all the features of the standard version, plus it can act as a controller for other Moog analog devices. Last but not least, the Moog Etherwave is also available in kit form, enabling users to customize their theremin's housing and circuitry.

Analog theremins built with tube circuitry are also of great interest to theremin-o-philes seeking to recreate the elusive tones of early devices. Theremin expert Arthur Harrison has built a Web site, Theremin.us, dedicated to spreading knowledge about theremins and theremin-building. He offers kits for sale as well as detailed instructional articles, including schematics, on constructing vacuum tube powered theremins. Even Harrison, however, warns against the dangers involved with building these devices, which use lethal AC voltages.

Other types of theremins include:

Endlessly eerie and magnificently mysterious, the theremin has inspired musicians, scientists, makers and artists for generations -- and will, no doubt, continue to do so for generations to come.

Find lots more information about this noir novelty on the next page.