The Big Briar Theremin Years and Beyond, 1978 - 2004

Big Briar (1978 – 2002)

With the creation of Bob’s new company, Big Briar in 1978, the new focus was on controllers and computer interfacing. As mentioned in a newsletter from 1982, “Big Briar, Inc. specializes in designing and building electronic and computer music controllers, as well as musical instruments and systems using electronic and computer technology.” The theremin remained an excellent source of inspiration for these goals.

The first “theremin” to be produced and sold by Big Briar was the Model 500 Theremin-Type Controller. Relatively little is known about this non-sound-generating, controller-only model, as it is very rare and practically unknown in the theremin community. The little information that we have comes from a 1982 pamphlet that advertised a range of controllers including the Model 500, as well as a keyboard controller and a touch plate controller, all featuring digital or analog control outputs.

The Model 500 replicates the configuration of the theremin, with a pitch and volume antenna reminiscent of the Vanguard’s ‘shepherd's crook’ open loop, made of polished, gold-anodized aluminum. In the 1982 pamphlet, the cabinet was shown as a small, simple hand-finished hardwood cabinet, about the size of a Melodia or Troubador theremin. Later, in a small black and white advertisement in the May 1984 issue of Keyboard Magazine, a different design for the Model 500 controller was revealed, which appeared to have a white laminate-topped plywood cabinet in a similar style to the Big Briar Touch-Sensitive Plate currently owned by Microsoft Research partner and designer Bill Buxton.

The Model 500 has two tuning knobs, like most any theremin, which “compensate for variations in the environment.” There is an on/off switch, a standby switch, and “indicator lamps that tell when the controller is correctly tuned.” It is powered by dual rail 12 to 18 volts at 50 milliamps, which could be generated from an optional built in line-operated power supply.

The analog version has two control voltage (CV) signal outputs. The pitch CV ranges from zero to +5 volts as the player’s hand approaches the pitch antenna. With the standard of one volt per octave, this would yield a five octave playable ‘theremin’. There is also a gate signal activated as the hand is brought into the antenna’s field, to prevent triggering when there is no one near the controller. The volume CV also ranges from +5 to zero volts as the player’s hand approaches the antenna.

The digital version sends 14 bit data, control in and out lines, and an address line that identifies which antenna output is being measured. This pre-MIDI digital control was TTL and CMOS compatible for interfacing with early computers and digital programmers of the time.

In 1991, Big Briar released Bob’s newest theremin design, the Series 91. The April 1992 Information Bulletin No. 9201 described the Series 91 as using “contemporary solid-state digital and analog technology to implement the tone color and playing characteristics of the space-controlled instruments designed by Leon Theremin during the period 1930 – 1980.” The Bulletin also notes that “several cabinet styles and interface options are available,” which were listed as options A, B, and C. They are described at the end of this section, with notes about their respective designs.

The Series 91 theremins are not true superheterodyne theremins, unlike all of Bob’s previous analog designs and the theremins designed by Lev Termen. They consist of two separately-operating parts for control and tone generation. The tone circuit uses “contemporary analog synthesizer technology” which is designed to emulate the waveforms and spectral characteristics of Lev Termen’s instruments. There are four timbre options of varying brightness accessible from a dial on the faceplate of the instrument. The Series 91 theremin has G6 (2 ½ octaves above middle C) as its highest note, and can produce any pitch below that, giving it approximately a six octave playing range.

Looking inside the Series 91 theremins, one can observe two large coils of approximately three inches in diameter and eight to twelve inches in length, wrapped with extremely fine gauge enamel coated wire. These coils are reminiscent of those found in Termen’s own theremin designs, but instead of being connected to radio frequency oscillator circuits, they are coupled to phase detection circuits which detect when the pitch antenna circuit is excited with a 257 kHz signal, and when the volume antenna circuit is excited with a 450 kHz signal. These circuits generate control voltages which in turn control the sound generating circuits. Interestingly, these frequencies are also similar to the ones used in Lev’s early 1930s theremins, and were probably selected by Bob as starting points for his design of the Series 91s.

The Series 91 has a small built-in speaker, which is powered by a 10 watt amplifier, which could also be used to power an external 8 ohm speaker. It can be operated in either 120 or 240 volts mains power by a selectable switch. The instruction manual notes that if the mains socket or extension cable is ungrounded, the player should try switching the orientation of the plug for the “clearest tone and most sensitive antenna response.”

A road case and small performance speaker could be purchased as accessories for the Series 91 theremin. The speaker is six inch in diameter, high efficient, and mounted on a 16 inch square, clear, plastic baffle. The design is an homage to Lev Termen’s visually striking diamond speakers that accompanied his theremins from the early 1930s, which mounted the speaker on a diamond baffle and elevated it nearer to the player’s head.

According to the April 1992 Information Bulletin No. 9201, options A and B retailed for $1,800, with an additional $300 charge for option C, the Contemporary Cabinet. The road case was advertised for $325 and the speaker for $150. By November 1994, the prices increased approximately 40% across the board, with a few new design options listed in Information Bulletin No. 9201A, including a black cabinet for the 91A as well as black and walnut options for the 91C.

Bulletin No. 9201 also advertised an Option M modification, for a MIDI interface which would add MIDI inputs and outputs on the power panel on the underside of the theremin, and a front panel keypad and display. The description of the features was detailed enough to suggest the option was ready and available, but none of the Series 91 theremins sold are known to have a MIDI interface. Further research has shown that, according to Rudi Linhard, the designer of the MIDI circuit for the Ethervox (see below), Bob had initially hired a professor from a local university in Asheville to design the circuit. However, development stopped and a prototype never materialized. Later, in bulletin No. 9201A, the MIDI option was listed as “not currently available” and that a MIDI upgrade was planned for early 1995. This of course did not happen either, and a MIDI capable theremin was not to be seen until the release of the Big Briar Ethervox theremin in 1998.

According to engineer Stephen Dunnington, who was working for Big Briar at the time, it is estimated that around 150 Series 91 Theremins were made from 1991 to 1997. He indicted that Option A was the most popular, with Option B coming second, and Option C even rarer, due to the high cost and complicated cabinet design. Steve has also noted that most every component of the Series 91s were built in the shop at Big Briar, and that Bob had meticulously inspected every theremin shipped. A true labor of love.

Series 91 A “Traditional Cabinet”


Inspired by the cabinet of the iconic 1929 RCA Theremin, it was similar in size and shape to that instrument, but with a removable stand for travel. It featured high quality hardwood, with a hand rubbed lacquer finish for a dark brown color, or by special order in black. It’s little wonder that this cabinet style was the most popular ordered option, as it emulates the look of the classic quintessential theremin.

Series 91 B “U-Shaped Cabinet”


Inspired by Lev Termen’s 1960s era Moscow/Soviet theremins, this cabinet design was minimal, in a U shape, with vertical spaces for the larger pitch and volume coils, and space for the chassis and components below. Lev’s cabinets had simple, low profile stands, which made the theremins top-heavy. Fortunately, the Series 91s were lighter in weight, being solid state rather than employing vacuum tube technology, so this was not a concern. The 91B was plywood veneered with back Formica for a glossy sleek appearance. With its straightforward construction, these were the only cabinets made in house at Big Briar, rather than contracted to local woodworkers.

Series 91 C “Contemporary Cabinet”


Designed by sculptor and theremin enthusiast Dave McCornack, this cabinet has an unusual appearance, somewhat anthropomorphic or alien like, with long spindly legs posed a little like a quadruped standing at attention. The main cabinet is multifaceted, has angled sides and a steep slanting front. Also including detachable legs, these cabinets were made from cherry wood, with a hand rubbed lacquer finish in a light color or by special order in black or walnut. Unlike the others in the series, the antennas were polished copper with a clear lacquer protective coat.

Similar in size and shape to Bob’s Troubador theremin, the Etherwave is a solid-state analog theremin that mounts to a standard microphone stand, and is provided with a grounded power transformer. In place of the Troubador’s flat metal plate for the volume control antenna, the Etherwave returns to the classic volume loop shape not unlike the RCA Theremin, albeit smaller in size. In comparison with the Troubador, the Etherwave was designed to be mass produced using more common and readily available parts, and added more timbre options through the “Brightness” and “Waveform” controls. This theremin featured a five octave range and was far more affordable than the professional Series 91 theremins that Big Briar was concurrently producing.

Like the Melodia and Bob’s first theremin, the 201, this instrument was first introduced as the “EM Theremin” in a DIY article written by Bob for the February 1996 issue of Electronic Musician. A note in the article states that the theremin could be purchased from Big Briar as a kit, priced at $229. The kit version consisted of a pre-assembled and tested circuit board and an unfinished hardwood cabinet. Included with the theremin kit was an audio CD of Clara Rockmore’s “The Art of the Theremin” (recorded by Bob), an instructional VHS tape featuring Lydia Kavina, a manual, and the document “Understanding, Customizing, and Hot-Rodding Your Etherwave™ Theremin.” Later in 1996, Big Briar started selling ready-built and finished Etherwave theremins in a black instrument-grade painted finish for about $100 more.

The fifteen page “Customizing” document was created in response to many requests for information on how to adapt the Etherwave theremin to meet special technical requirements. This included options such as control voltage outputs, a foot pedal for controlling volume, and a left-handed playing modification which transposed the pitch antenna to the left and volume antenna to the right. Releasing the theremin schematic and providing both the ideas for modifying the instrument and the ability to do so via dedicated spaces on the circuit board harkens back to Bob’s early theremin designs, which he wrote about for the hobbyist magazines. Some of these features would be offered by Moog Music in 2008 as “Factory Modifications”, requiring the owner to send their theremin to the factory for an upgrade. The options included a pitch preview modification and an LED power indicator. Eventually Moog Music implemented most of the original guidebook’s hot-rodding options in the 2009 “Etherwave Plus” model, selling for about $500 or as an upgrade kit for the original Etherwave, priced at about $150.

The Moog Signature Series Etherwave was a special edition of the instrument, signed by Bob in silver on the top of the cabinet. Each theremin was tested personally by Bob before he signed it. These were discontinued in early 2004 and are rare and sought after theremins.

During its quarter century of production, the Etherwave has remained little changed from its original form. In terms of production and sales, it has outsold all other Moog products combined.

With the planned but undelivered MIDI functionality for the Series 91 theremins, and a “MIDI Theremin Market Survey” sent out to theremin owners in late 1996, it’s no surprise that the next theremin made by Big Briar, the Ethervox, would have MIDI capabilities.

First shown at the week-long Theremin Festival in Portland, Maine in the summer of 1997 and available for purchase in late 1997/early 1998, the Ethervox was a new theremin that was built upon the foundation of previous deigns and technology, while also introducing brand new features of MIDI control.

Replacing the Series 91, this professional grade, high quality theremin was housed in an attractive mahogany cabinet that sat on a base with removable legs for compact storage and easier shipping. The triangular shape of the cabinet evokes the design details of the Vanguard or even the RCA Theremin but feels more modern, with long tapered round legs and generous radii on all the corners. One thoughtful design detail is the inclusion of two small finger holes on the sides of the cabinet at the top, allowing for easy lifting and positioning of the cabinet when removing the instrument from or placing it onto the base.

Like Bob’s earlier theremins, the front panel control features pitch and volume adjustments, as well as waveform, brightness, and filter knobs for controlling the waveform. New to this theremin is a range switch which allows the player to select different octave ranges (2, 3 and 4 octaves extension above middle C) and a display with controls for accessing the MIDI features.

Since a theremin produces a continuously changing pitch as the player’s hand approach the antenna, the MIDI software needed an innovative way to send pitch data to a synthesizer. To solve this, the theremin transmits pitch data as a stream of pitch bend messages, at a user-selected rate of 60-200 times per second, in 7 or 14 bit resolution. Volume data is transmitted as a stream of master volume messages. The theremin can also be set to trigger individual notes of pre-programmed or user-programmable scales, such as chromatic, whole tone, tritones, pentatonic, etc..

The Ethervox has two ‘voice’ options for its tone generation; a true analog, heterodyne theremin similar to other past theremins built by Bob (Voice 1), and a synthesized sound, not unlike the Series 91 theremin, which is controlled by the theremin-to-MIDI controller inside the Ethervox (Voice 2). Both sounds can be activated at the same time through switches on the front panel, and can be recorded from discrete outputs on the theremin itself or from the ‘snake’ box which can be attached to the instrument. The ‘snake’ box is on a ten foot cord that allows connection of MIDI In, Out, and Thru, a foot switch input, a pedal input, pitch and volume CV, and balanced as well as unbalanced Voice 1 and Voice 2 audio outputs.

Highly regarded, the analog Voice 1 sound is believed by many to be one of the best sounding theremins that Bob has designed.

Moog Music (2004)

The Etherwave Pro is the final theremin designed by Bob. Prototyped on breadboards mounted to an old Etherwave, evidently his goal was to make a great sounding professional theremin with a small foot print, and that’s what he accomplished. It is unlike any theremin that came before, and has been praised for not only its great sound, portability, and playability, but also for its appearance. With a graceful and atypical cabinet designed by the Tennessee firm Sandbox, it won a 2005 Excellence in Design award from Appliance Design Magazine in the category "Leisure Appliances.”

It was introduced at Winter NAMM 2004 in Anaheim, and shipped mid-2004. In the press release, Moog Music President Michael Adams said, “As the leader in theremins our customers have been requesting a professional theremin with greater range and portability, the Etherwave Pro accomplishes both of these objectives in a package that matches the intrigue that all theremin players enjoy on stage.” To quote the manual, “it combines Dr. Robert Moog’s 50 years of theremin expertise with a cutting edge cabinet design.”

The cabinet features a gracefully curved continuous piece of birds-eye maple, with nickel plated controls and two prominent, matching maple knobs for the volume and pitch tuning controls. The cabinet stands vertical, sliding onto a modified mic stand. The pitch antenna connects to a horizontal arm that allows for an appropriate spacing between the volume and pitch antenna. This arm also contains some of the pitch control circuitry which contributes to its excellent interval spacing. Another thoughtful, small detail is the use of a headphone jack and socket for the volume loop, allowing a secure electrical connection with off-the-shelf parts, and giving tactile feedback to the operator when properly connected.

The Etherwave Pro embodies the best of all of Bob’s previous theremin designs (except MIDI), such as six and one-half octave range, a three position octave range switch, five timbre options, waveform, brightness, and filter controls, monitoring outputs for a tuner and headphones, and pitch and volume CV outputs. Looking at the schematic, the oscillator circuits are a more advanced version of the Etherwave oscillator design. The wave shaping circuits are similar to that of the Etherwave, while the entire wave shaping and filtering section is nearly identical to that of the Ethervox. The Etherwave Pro can be powered by 100 to 240 volt mains, without needing to be switched.

Announcing that production would soon cease, the last run of 80 models were going to have a solid walnut body instead of black composite material. Approximately 1,500 Etherwave Pros were made. Currently they are highly prized and will fetch an impressive price, a testament to the unsurpassed attributes of its design.

Without question Bob Moog is the world's most-successful theremin designer and producer. His theremins have outsold all other makes of theremins combined, worldwide. Designing and building theremins bookends Bob’s impressive career in musical instrument design. To quote Bob’s daughter and Executive Director of The Bob Moog Foundation, Michelle Moog-Koussa, “I honestly believe he would have been happy designing theremins his entire life if the synthesizer had not come into being.”