Theremin Brings Good Vibes
The Theremin is considered the world’s first electronic instrument. It can be heard in Led Zeppelin’s “Whole Lotta Love,” and in the soundtracks of classic (and less-than-classic) films like The Day the Earth Stood Still, Hitchcock’s Spellbound and the recent Mars Attacks!
Designed by Russian-born inventor Lev Termen (see sidebar) and first manufactured by RCA, the original Theremin looks like a wooden podium in a high-school auditorium that has sprouted antennas. These are what make the music that wafts from the speaker in eerie, wavering tones whenever movement-usually a human hand-runs through the magnetic field they create. The sound is like “candy for the soul,” said Gary Bogue, a networking engineer at Concentric Network Corp. (Cupertino, Calif.).
Without ever actually touching the instrument, the tiny electrical effect of a player’s hands in space controls pitch over a range of more than five octaves. The dynamic level ranges from fortissimo (very loud) to complete silence. Every gesture translates into a continuous pitch or volume change, making the Theremin a highly expressive musical instrument, and making the player look a bit like a magician.
“I’m often amazed at the thought that this was first developed in a period when people where just trying to understand how to buy and operate a radio receiver,” said Mike Fugere, an engineering project manager at Rockwell Automation, the company’s industrial-automation group in Lebanon, N.H.
The original Theremin was built using vacuum tubes, but in the early 1960s Robert Moog-inventor of the synthesizer that bears his name-published one of the first transistorized Theremin schematics. That led to a wave of Theremins using hybrid digital/analog electronics and incorporating musical instrument digital interface (MIDI) output. Many EEs spend their off-hours constructing such models, as the few remaining originals are now in museums or owned by wealthy private collectors.
“I’ve built the PAiA Electronics’ Theremax and a Big Briar Etherwave model,” said Barile, referring to two popular and inexpensive do-it-yourself digital Theremins. “Both are great, because you don’t have to spend six months tracking down parts and etching your own circuit boards. I have plans to build a transistorized Theremin, and one day I’ll build a tube Theremin-for nostalgia’s sake.”
For his part, Rockwell’s Fugere is looking to design and build a hybrid-tube-based Theremin to add to his homemade collection of Theremaxes.
John Simonton, the president of 30-year-old PAiA Electronics in Edmond, Okla., is not surprised at the popularity of his company’s “Tmax.” Trained as an EE, he knew he was on to something that would attract like-minded souls.
“At the time I designed and built Tmax, it was very satisfying because it was a ‘return-to-my-roots’ sort of thing,” Simonton said. “I hadn’t worked with any radio-frequency stuff since I was a boy, and my previous products were vacuum-tube amplifier things. It was a lot of fun.”
Moog’s Big Briar company in Asheville, N.C., offers an inexpensive digital Theremin kit, too, alongside its professional models. Moog said the Theremin was a big inspiration for his renowned Moog synthesizer.
“I never stopped working with Theremins,” he said. “Even while I worked for Moog Music and Kurzweil [pioneering electronic-instrument firms], I built custom Theremins from time to time. After I left Kurzweil and returned to North Carolina, I decided to come up with a completely new Theremin design, which became our Series 91 instruments. We’ve been making them for over six years now.”
Virtual renaissance
But the real Theremin renaissance was born on the Internet. Noting interest in Theremins in newsgroups and mailing lists, PAiA’s Simonton decided to introduce his product on the Web with a “mystery circuit” contest. It clicked with Netheads. “The Net changed all the rules,” he said. “The Web makes it so easy for people to find info on what would otherwise be an obscure and difficult instrument for which to locate [parts].”
The Web-only Theremin Enthusiasts Club International, based in Canada and located at www.he.net/~enternet/teci/teci.html, continues to draw new members-more than 500 so far, many of them technical professionals. They surf the online bulletin board to swap parts, share tips or simply gush over their favorite instrument.
The enthusiasm has spilled over into actual physical meetings. Last month’s week-long festival in Maine featured concerts by the handful of Theremin virtuosos, screenings of films with Theremin soundtracks and technical symposiums. A “Theremin celebration” is planned at the Loud Music Festival in Northampton, Mass., in September.
Signal mix
The basic principle behind the Theremin is known as heterodyning: mixing two signals of different frequencies and extracting the difference. The pitch circuit of the Theremin uses two RF oscillators, one fixed and one variable, to create this effect. Moving the hands near the pitch antenna changes the speed of the variable oscillator, and the difference between the two comes out as a musical note. The volume circuit works in a similar manner.
The advent of the transistor made the oscillators-originally vacuum tubes-considerably more stable. Analog Theremins usually use four transistor oscillators arranged in two pairs. Each pair forms a beat-frequency oscillator, the outputs of which are modulated by the effect of a player’s hand capacitance near each antenna.
Digital Theremins use CMOS oscillators and logic gates to produce two dc levels. One dc level varies with the proximity of the player’s hands from the pitch antenna; the other varies when the volume antenna is approached. This circuit is where many electronic engineers find a place to construct a myriad of personal imprints, or find ready-made variations at Web sites such as that of the University of Glasgow’s Department of Physics and Astronomy in Scotland.
The Internet is even providing new ways to play the instrument. Most notable is the Inner Communications Labs’ Web site, based in Japan, which enables visitors to play a Shockwave-enabled online Theremin on a Web browser.
However, Rockwell’s Fugere sees further and richer uses for the actual physical hallowed instrument-for instance, as an instructional tool for youngsters interested in electronics. He and others, including Moog, regularly take their Theremins into classrooms to demonstrate basic principles of waves, sound and E-fields.