The ‘Hugoniot Organ’. Charles-Emile Hugoniot . France, 1921.

Hugoniot's patent for a tone-wheel sound generator December 1919
A diagram from Hugoniot’s patent for a tone-wheel sound generator December 1919

CharlesEmile Hugoniot ( died; France, 1927 ) was a French mechanic, researcher and inventor of early electronic musical instruments. Hugoniot was awarded seven patents in France from 1919-1923 for various methods of sound generation including tone-wheels and photo-electrical tone generators.

Starting in 1919, Hugoniot began a process of improving existing sound generation devices of the period, first; Thaddeus Cahill’s electro-magnetic tone-wheels (from Cahill’s patent’s that would have been known to him in France) and continuing to electromagnetic steel discs and photo-electrical methods possibly influenced by the South African physicist, Hendrik van der Bijl’s patents from 1916. By doing so, Hugoniot introduced these new methods to a French group of electronic engineers.

Hugoniot Appears to have constructed only one instrument–  a photo-electric organ described in his patent (FR550.370) In 1921. The instrument was one of the first to use a photoelectric technique to generate sound: Hugoniot projected a light beam onto a selenium photo-voltaic cell through an array of 12 rotating discs cut with with concentric rings of radial slits. The frequency (and speed of rotation) generated an electrical pulse from the photo-voltaic cell that equated to an octave pitch.

Hugoniot’s died in 1927 before he could develop his ideas any further than prototypes yet he left behind a legacy of innovation that influenced a new generation of French pioneering instrument designers including Pierre Toulon and Givelet & Coupleaux.

Hugoniot's patent for a photo-electrical sound generator August 1921
Hugoniot’s patent for a photo-electrical sound generator August 1921

With this scheme the various types of wave forms for different timbres may be placed in radial sectors on a disk; another disk carrying the scanning slits in circular tracks rotates before this wave-form disk. A source of light and photocell complete the translating arrangements. Each slit track scans its corresponding wave cycle at a speed corresponding to one pitch of an approximate tempered scale. Thus, one wave and one slit track serve for each tone frequency of the tempered scale. Naturally the lowest pitch tracks are nearest the center and the highest are nearest the circumference of the scanning disk.

Another interesting arrangement is that used by Lesti and Sammis in the Polytone. Here, instead of using a series of similar wave-form cycles on a continuous track, with a single scanning device, only one complete such cycle is used with periodic scanning by a series of similar scanning slits, equispaced on a continuous track. The slit spacing is precisely equal to the wave-form lengths, so that this wave form is repeated at the scanning frequency; i.e., the number of slits passing it per second. The same method was disclosed as early as 1921 by the French inventor Hugoniot, who described an electrical musical instrument of this type in his patent’

A description of Hugoniot’s photo-electrical sound generation method from ‘Electronic Music and Instruments’ Institute of Radio Engineers, 1936


Bush, D., & Kassel, R. (2004;2006;). The organ: An encyclopedia. London: Taylor and Francis. doi:10.4324/9780203643914 P.167

‘Electronic Music and Instruments’ By Benjamin F. Miessner (Miessner Inventions, Inc., Millburn, New Jersey) . Institute of Radio Engineers. 1936. (

The Magneton. Wilhelm Lenk & Rudolf Stelzhammer. Austria, 1930

Rudolf Stelzhammer and Wilhelm Lenk demonstrating the Magenton at the Erfindermesse, London 1935
Rudolf Stelzhammer and Wilhelm Lenk demonstrating the Magenton at the Erfindermesse, London 1935

The Magneton, designed by Wilhelm Lenk at the University of Vienna, was a tone-wheel organ-like electronic instrument based on the same principles as Cahill’s Telharmonium (c1900)  and the later Hammond Organ of Laurens Hammond and  John Hanert; the electromagnetic principle of producing a voltage tone and associated timbres by spinning varied shaped metallic wheels within a magnetic field.

Tone-wheels of the Mageton
Tone-wheels of the Magneton arranged over 12 axles. Technology Museum Vienna.

The instrument’s contribution to tonewheel technology was to achieve a constant fixed rotation by using a frequency controlled motor regulator. This allowed the player to easily and accurately transpose the instruments switch at the flick of a switch.

Rudolf Stelzhammer and the Magenton in 1935
Rudolf Stelzhammer and the Magenton in 1935

The first promotional model of the instrument was produced by the Vienna piano company Stelzhammer in 1930 – four years before the first Hammond organ hit the market. The instrument was designed as a practice instrument for ‘real’ pipe organs and as a way of encouraging active participation from the congregation in sacred music (as espoused by the “Popular Liturgy Movement” in pre-war Austria).

The Stelzhammer Magneton tone wheel organ, 1930.
The Stelzhammer Magneton tone wheel organ, 1930.

“The slavish imitation of the sound of an organ and its characteristic rigidity was deliberately avoided, thereby giving the tone character of the instrument a number of special characteristics. What I like particularly in the magneton, 8 although I grew up with the pipe organ and have been inseparably associated with it for 50 years, is the fact that this new instrument is not an enemy of the historic organ.”

Vinzenz Gollerin the ‘Zeitschrift fur Instrumentenbau’ Vol. 54, 1933/34, p. 103

Despite a promising start, the Magneton failed commercially – only a few production models were built. A single surviving model can be found at the Vienna Museum of Technology, Austria.

Wilhelm Lenk
Wilhelm Lenk


The Stelzhamer Piano shop at Barnabitengasse 1060 Wien.
The Stelzhamer Piano shop at Barnabitengasse 1060 Wien.

Rudolf Stelzhammer. Biographical notes.

Rudolf Stelzhammer was born into a Viennese family of piano makers on the  03.11.1893. After learning the craft of piano construction and working in the family business he travelled throughout Europe and America working for large instrument manufacturers. Returning to Austria in 1924 he founded his own company in Vienna and from 1935 became the ‘guild master’ of the Austrian musical instrument producers. In 1966 Stelzhammer sold the business to the Ehrbar piano Company in Vienna. Stelzhammer was known for his scientific and electro-acoustic research which lead to several improvements in piano design. Stelzhammer was involved in the development of photoelectric experiments and was involved in the creation of the ‘Selenephon’ (1922) a device for printing optically recorded audio onto movie film. Rudolf Stelzhammer died in Vienna, Austria on 01.16.1967



Peter Donhauser, Elektrische Klangmaschinen. Die Pionierzeit in Deutschland und Österreich, 348 S., zahlr. s/w-Abb., Br., (Böhlau), Wien 2007. ISBN: 978-3-205-77593-5

The Organ: An Encyclopedia (Encyclopedia of Keyboard Instruments) by Douglas Bush, Richard Kassel (ISBN: 9780415941747)

S. Walter Fischer:. Technical In: L’Estrange Fawcett:. The world of film Amalthea-Verlag, Zurich, Leipzig, Vienna 1928, p 210-211

Franz Lechleitner: Selenophon. In: Oesterreichisches music lexicon. Online edition, Vienna 2002 ff. ISBN 3-7001-3077-5; Print Edition: Volume 4, Austrian Academy of Sciences, Vienna 2005, ISBN 3-7001-3046-5.

The ‘Mastersonic Organ’ John Goodell & Ellsworth Swedien, USA, 1949

The Mastersonic Organ was an improved tone wheel organ designed to produce more accurate pipe organ sounds. The designers,  John Goodell and Ellsworth Swedien, discovered that if they shaped the tone-wheel ‘pickups’ they could induce tones with different ‘natural’ harmonic content – rather than attempt to create a pure sine wave and artificially colour it as in the Hammond Organ. To achieve this the Mastersonic had individually shaped magnets for each tone wheel sound; a “string” magnet, a “flute” magnet, a “diapason” magnet, and so on.

Mastersonic Tone Generation
Mastersonic Tone Generation (Alan Conway Ashton ‘electronics, Music and Computers’ 1971)

“…There were twelve shafts with seven pitch wheels each which rotated near the irregularly shaped magnets wound with coils. Each of the pitch wheels contained twice as many rec­tangular teeth as the preceding one, so seven octaves were produced per shaft. Several differently shaped poles were dispersed radially around each wheel.”
Alan Conway Ashton electronics, Music and Computers

Each tone-wheel was shielded against magnetic interference from the other, adding to the bulk and complexity of the instrument. The instrument was controlled by a seven octave special keyboard, designed to simulate attack envelopes. The resulting sound was indeed a much more accurate pipe organ sound but at the expense of size; the Mastersonic was a huge, complex and expensive machine and few were built or sold.


‘Microsound’ Curtis Roads MIT 2001

ELECTRONICS, MUSIC AND COMPUTERS. Alan Conway Ashton. December 1971 UTEC-CSc-71-117

The ‘Electrone’ and ‘Melotone’ Leslie Bourn, United Kingdom, 1932


Since the 1920’s the Compton Organ Co had been the premier manufacturer of pipe organs for cinemas, churches and dance halls in the UK. In 1932 Compton developed their first electronic “pipe-less” organ the ‘Melotone’ intended as an add-on unit for conventional organs to extend their range. The Melotone’s sound was generated using the same tone-wheel technique as the Hammond Organ and the much earlier Telharmonium (1876), where a metal disc engraved with representations of sound waves spun within a magnetic field generating varying voltage tones. In this case two electrostatic tone wheels provided the sounds, amplified and fed to a large speaker horn in the organ loft. The Melotone was not intended as a complete instrument in itself and had it’s own ethereal synthetic character to contrast with a traditional pipe organ.

The Compton Melotone add-on unit
The Compton Melotone add-on unit

In 1938 Compton developed the Melotone concept into a stand-alone organ called the Electrone (or Theatrone) designed as a replacement for old pipe organs in churches and dance halls. This instrument had twelve tone generators and an organ-stop style range of voices. A post-war compact ‘economical’ version was brought out in 1952 also called the ‘Melotone’. Production of the organs continued until the 1960’s by which time tone-generator technology had become obsolete due to the arrival of cheaper and more dependable solid-state electronic circuitry.

One of the twelve tone wheels of the Compton Electrone
One of the twelve tone wheels of the Compton Electrone



The ‘Wave Organ’. Frank Morse Robb. Canada. 1927


The 1937 version of the Robb Wave Organ. Image; National Music Centre,© 2016 National Music Centre, Calgary.AB.
The 1937 version of the Robb Wave Organ. Image; National Music Centre,© 2016 National Music Centre, Calgary.AB.

The Robb Wave Organ designed by Morse Robb in Belleville, Ontario was an early pre-cursor, and said to be  musically superior, to the Hammond Organ. The instrument attempted to reproduce the sound of a cathedral pipe organ by amplifying sounds generated by a similar tone-wheel mechanism. Robb based his tone-wheel design on that of Melvin Severy’s ‘Choralcello’ but with the addition of amplification – which wasn’t available to Severy at the time.

Frank Morse Robb
Frank Morse Robb

“…Such an instrument as his, (Severy’s ‘Choralcello’) however, is both practically and theoretically impossible, as without amplification, far greater than the microphone type he suggests, nothing but the faintest trace of tones could be heard. The mere addition of amplification to his instrument would not be invention. If this were done, moreover, the instrument could not be made to function musically as the circuit and wiring arrangement set forth in his patent-would preclude that possibility due to internal resistance in the magnets. Every impulse generated by the tone disc would be absorbed in the circuits to such an extent that amplification would be impossible.”

Morse Robb's miniaturised tone wheels of the Wave Organ. From the collection of the Canada Science and Technology Museum, Ottowa, Ontarion Canada.
Morse Robb’s miniaturised tone wheels of the Wave Organ. From the collection of the Canada Science and Technology Museum, Ottowa, Ontario Canada.

Robb’s aim was to miniaturise elements of previous huge tone-wheel designs (‘Coralcello‘ of 1909 and ‘Telharmonium‘ 1897-1917) to create a practical, easy to maintain and affordable electronic organ. This was done by reducing the size and number of the tone wheels by adding a system of gears and increasing the number of notes on each wheel by  ‘doubling and redoubling the wave forms on the discs on one shaft’ . The instrument was equipped with twelve tone wheels representing each note, the ‘character’ or timbre of note – corresponding to organ stops and photographed from a cathode ray oscillograph – plus the harmonics of each fundamental note. The variation in pitch of each note was achieved by changing the speed of the tone wheel’s rotation giving the Wave Organ a total of five octaves. The tone wheels spinning within a magnetic field generated a voltage output of each note which was made audible by being passed to a valve amplifier and loudspeaker.

Significantly the Wave Organ was unique in that it tried to replicate real organ sounds by cutting the tone wheels to the shape of a photographic image of the waveform of a church organ – rather than mechanically reproducing and combining ‘pure’ tones and overtones like the Telharmonium and Hammond Organ. In this way the Wave organ can be seen as one of the earliest analog sampling

The 1937 version of the Robb Wave Organ. Image; National Music Centre,© 2016 National Music Centre, Calgary.AB.
Tone Wheel housing of the 1937 version of the Robb Wave Organ. Image; National Music Centre,© 2016 National Music Centre, Calgary.AB.

The prototype Wave Organ was built in 1927 and premiered in November of the same year at the Toronto Daily Star’s CFCA radio studio in Belleville and patented in 1928 (1930 in the USA). Robb planned to market the instrument by arranging a production contract with the General Electric Company in Schenectady, NY and later, organ builders Casavant Frères in Canada, however the worsening economic troubles of the 1930s depression permanently stalled the agreements in the spring of 1931 .

Undaunted by the commercial  failure of his first prototype, Robb produced a new, two manual, 32 note version of the Wave Organ in April 1934 and launched the ‘ Robb Wave Organ Company’- incorporated on 21 September 1934 – to market and sell the instrument. The first productions models became available in July 1936 and was publicly demonstrated at Eaton’s department stores in Toronto and Montréal. Despite an initial positive reaction Robb was unable to obtain funding for further production and in 1938 he abandoned the project – Only thirteen models were ever sold and the Wave Organ was taken off the market in 1941.

The 1937 version of the Robb Wave Organ. Image; National Music Centre,© 2016 National Music Centre, Calgary.AB.
The 1937 version of the Robb Wave Organ. Image; National Music Centre,© 2016 National Music Centre, Calgary.AB.

The Robb Wave Organ was more expensive than other electronic organs of the period – notably the American Hammond Organ, which used an almost identical tone-wheel technology – and sales suffered because of World War II. The last remaining Wave Organ prototype is preserved at the Canada Science and Technology Museum in Ontario.

Second version of Morse Robb’s ‘Wave Organ’ c1936

Michael J. Murphy professor RTA School of Media talks about the Robb Wave Organ

Frank Morse Robb

(born 28 January 1902 in Belleville, ON; died 5 August 1992 in Belleville)

Robb studied at McGill University from 1921 to 1924 and then returned to Belleville where in 1926 began research on the Robb Wave Organ. After the commercial failure of the Wave Organ, Robb applied his talent as an inventor to devices for the packing of guns during the Second World War. He became vice-president of his brother’s packing company and won acclaim as a silversmith. He also wrote a Sci-Fi -post nuclear holocaust novel Tan Ming (1955) under the pseudonym Lan Stormont (“An amusing fantasy in which a department store window dresser falls in love with a robot mannequin and manages to conjure into its body the soul of a princess named Tan Ming from a postholocaust future.”).

'Tan Ming' by
‘Tan Ming’ by Lan Stormont/Morse Robb 1955


‘Frank Morse Robb’s Wave Organ’ by Michael Murphy and Max Cotter. eContact! 17.3 — TIES 2014: The 8th Toronto International Electroacoustic Symposium

Canada Science and Technology Museum.

‘Encyclopedia of Music in Canada’.

‘New worlds of sound; electronics and the evolution of music in Canada’ Katharine Wright.Canada Science and Technology Museums Corporation Société des musées de sciences et technologies du Canada Ottawa, Canada

The ‘Choralcelo’ Melvin Linwood Severy & George.B. Sinclair. USA, 1909

The keyboard manual of a Choralcelo installed in Denver Colorado. Photo Art Reblitz ca 1970.

The Choralcelo (“heavenly Voices” – pronounced: ‘Chor-al-Sello’) was a hybrid electronic and electro-acoustic instrument conceived as a high-end commercial domestic organ, aimed at wealthy owners of large country houses in the USA – houses large enough to accommodate the huge instrument. The Choralcelo was designed and developed by Melvin L. Severy with the assistance of his brother in law George B. Sinclair and manufactured by the ‘Choralcelo Manufacturing Co’ in Boston, Massachusetts. Later models were extensively redesigned and improved by Quincy Sewall Cabot, inventor of the ‘Synthetic Tone’.

Melvin Severy b.1863 Melrose, Mass; d. California 1951
Melvin Severy b.1863 Melrose, Mass; d. California 1951 
Severy was a prolific inventor (his patents included: printing presses, typewriters, solar heating systems, a camera, steam engines, fluid drives among many others) engineer musician, composer and author. The Choralcelo itself was a custom combination of the numerous electro-acoustic musical devices that Severy had designed since 1880 – electro-magnetic keyboard controls, tone generators and magnetic–acoustic string resonators 1“First Choralcelo Concert Proves Highly Successful,” The Musical Age (1 May 1909) . The first version of the Choralcelo was presented to the public on the 27th April 1909 at the Boston Symphony Hall, Boston, Mass accompanied by a soprano singer and forty members of the Boston Symphony Orchestra:

“First Choralcelo concert proves highly successful

As for the Choralcelo itself, it proved an interesting and unique instrument. Fronting the audience from the platform was a mahogany box to disguise an upright piano somewhat exaggerated, and with two rows of keys. The Instrument, it was announced, resulted from twenty one years of persistent labour on the part of it’s inventor Melville (sic) L. Severy and George D. Sinclair both of Boston. The Choralcelo obtains sound of the violincello, the trumpet and the French horn , the oboe and the bassoon, the harp and the pipe organ from a single compass from the wire strings used in the pianoforte, which are vibrated by means of small electromagnets stationed at scientifically determined points along their length.
The surprise in the Choralcelo is that the ordinary piano string can be made to give more sounds than those obtained from it under the blows of the hammer, and the variety of these sounds is great on the account of the immensely increased possibility of making what the student musician knows as overtone. The concert this evening faithfully demonstrated the merits of the Choralcelo, and it may be expected to contribute important things to music. Great skill is required in it’s handling. The player is embarrassed somewhat by the very largeness of the means at his disposal. He must learn to select. With careful study this new instrument is designed to do many and large things and the contention of it’s inventor seems to be fully justified” 2 The Musical Age. New York, May 1st 1909.
programme of the first Choralcelo concert, Boston, 1909.
programme of the first Choralcelo concert, Boston, 1909.
In 1915 The Choralcelo company was taken over by Wilbur Farrington and A. Hoffman (who, in some reports is named as its inventor). Sheets argues that by 1917 up to 100 of the instruments were produced 3Sheets, Arian, (2013) Choralcelo, Grove Music Online. Retrieved 27 Nov. 2021, from  At least six of the instruments are known to have been sold4Jenkins, C.W (2002) The Choralcelo, Amica Bulletin. AMICA International
Automatic Musical Instrument Collectors’ Association
and several  continued to be used up unit the 1960’s – no working examples have survived.
The Choralcelo was a direct contemporary of the Telharmonium, though not quite as large, was still a huge instrument and, for the organ section of the instrument, used a similar electromagnetic tone-wheel sound generation method as the Telharmonium combined with a set of electromagnetically operated and sustained piano strings.
The visible part of the Choralcelo consisted of two keyboards, the upper (piano) keyboard having 64 keys and the lower 88 (piano and ‘organ’), controlling the invisible part of the instrument, usually in the basement of the house, consisting of 88 tone wheels and a set of piano strings and bells that were vibrated by electromagnets and a set of hammers. The keyboards also had a set of organ style stops to control the timbre and fundamentals of the tone that could then be passed through cardboard, hardwood, softwood, glass, steel or “bass-buggy” spring resonators to give the sound a particular tone.The Choralcelo also incorporated a pianola style paper roll mechanism for playing ‘pre-recorded’ music and a 32 note pedal board system. The entire machine could occupy two basements of a house, the keyboards and ‘loudspeakers’ being the only visible part of the instrument.

Sounds of the Choralcelo

“Poor Little Butterfly” from an original 78rpm glass master live 1942 recording, hand played by Regene Farrington, wife of Wilber Farrington, President of The Choralcelo Co. Recorded in the Choralcelo Studio in New York City. (from: C. W. Jenkins, AMICA)

Promotional brochure from the  Choralcelo Manufacturing Co

Detailed History of the Choralcelo from “History Of the Choralcelo” by W.Jenkins

“The information furnished is based on forty years of acquaintance with the instrument, and on three complete Choralcelo instruments at hand, friendship with one of the principals, interviews with others involved in the work, family members, original blueprints, all the patents issued, (and there were many) and original documents from the archives. “

“The story of the Choralcelo is largely the story of two men… Melvin L. Severy, born in 1863 in Melrose, Mass; died in California in 1951; and Wilber E. Farrington, born 1869, died 1945. Severy was a brilliantly gifted, multi-faceted inventor who secured patents on a printing press, solar heating, a camera, fluid drive, and many others, besides the Choralcelo. He was a scholar, artist, musical composer, and author. His grandson recalls that he was interested in secret passages in the pyramids, to name one of his many interests. Severy was assisted in his experimentation by his brother-in-law, George B. Sinclair. They had married Flint sisters. Wilber Farrington was an idealistic, philosophic visionary who devoted the majority of his life to his love of the unique tone of the novel instrument and his determination to see it successfully developed and manufactured. He was a charismatic and effective fundraiser and invested his own fortune in the work.There had been many efforts at strengthening or lengthening the tone of piano strings electrically.

Remains of a Choralcelo at the National Music Museum, Vermilion Sands, South Dakota
Remains of a Choralcelo at the National Music Museum, Vermilion Sands, South Dakota

As early as 1876, Elisha Gray had patented a single note oscillator; and in 1890 Eli C. Ohmart filed a patent on prolonging the tone of piano strings electromagnetically… the patent was assigned to Melvin Severy. The principle being worked on was simple… magnets were placed behind the strings of the piano, and accurately timed pulses of DC current were fed to the magnets coinciding with the natural periodicity of the strings.. for example, if note A vibrated at 440 vibrations per second, then 440 pulses of current per second would be fed to the magnets for that note, and sustained organ-like tone would be produced without the use of the hammers. The mechanism which accomplished this was the interruptor, powered by a small electric motor, which had nine brass cylinders 3 1/2″ long spinning at predetermined speeds. Each cylinder had eight make and break tracks 1/4 inch wide, alternate spaces being set in an enamel, a non-conductor. Sterling silver brushes rode on these tracks. The lowest notes required about 20 pulses per second, and the highest, about two thousand. The overwhelmingly difficult part was the governing of this device… the very slightest deviation and the frequency of the pulses would not coincide with the natural periodicity of the strings, and the tone will die. Patent after patent was filed for variations on governing mechanisms, some of them so elaborate that they were complicated mechanisms in themselves.

The basic concept of tone production, though simple, proved nearly impossible in execution… matching, on one side, an already tuned vibrating body, with perfectly matching pulses of magnetism, ranging anywhere from 20 vibrations per second to 2,000. The governing device controlling the speed of the make and break cylinders would not only have to provide such absolute perfection whenever called for, but would also have to be able to compensate for the vagaries of the electric current generated in that day, which powered the motor the drove the governor… to do this, it would have to be able to keep the cylinders rotating without the slightest deviation even if the motor driving the assembly slowed down or speeded up. If the speed of the cylinders changed while the instrument was being played, the tone would die out.

Remains of a Choralcelo at the National Music Museum, Vermilion Sands, South Dakota
Remains of a Choralcelo at the National Music Museum, Vermilion Sands, South Dakota

An elegantly simple, brilliant magnetic combination governor and clutch evolved, which performed perfectly without physical contact, so there could be no overheating, and there were no clutch pads or other friction assemblies to wear out. Even today it is a marvel of brilliant application of principles of physics , and a marvel at least to those who are aware of what they are seeing to watch the spinning copper band drive the heavy flywheel merely by cutting through the invisible magnetic force. It is so disarmingly simple one could have no inkling of the years of labor which preceded it. Appreciating what it represents, I still have a feeling of awe. I doubt there has ever been anything like it, before or since. It was through the many mechanisms Severy laboured over and patented in his determination to solve the problem that fluid drive evolved. The first concert was given in 1905, and was by invitation.

The Choralcelo of that first phase of development was an impressive upright piano with one keyboard, usually with a roll player; the case of the finest grain mahogany with beautifully hand-carved openwork scroll panels. The tone could be varied by means of a slider near the left hand. It was the first tone produced without physical contact of some kind, and the tones produced invoked orchestral instruments minus the sound of the bow on the string or the breath of the flutist.


Development continued and a two manual instrument marked the second level, or phase, of the evolution of the Choralcelo. It still had the piano keyboard and piano strings which were excited by magnets. The piano strings were tuned by means of screws to attain greater stability. There was an organ keyboard above the first one, and a row of stops to control the range of tone units. These took the form of sets of tuned bars, or plates, which could be of steel, or wood, or aluminium, or sometimes glass. There were usually 41 to a set, and typically they varied in length from 5 3/4″ to 10 1/2″, and usually were about 5/16″ thick. Materials other than steel had small iron armatures affixed so that there would be response to the magnets.


Installed directly over these bars were resonating chambers, usually cylindrical fiber tubes, open at each end, which reinforced the tone, just as one sees in marimbas and vibraharps, The tone production was entirely acoustic; there was nothing electronic about the Choralcelo… no amplifiers, no loud speakers, no tubes… nothing of the sort. These sets of bars were remote from the main console and could be placed anywhere. The switching and control devices were remote from the main console and could be contained in two cabinets, each about 5 1/2′ high, and installed in the basement, along with the interrupter mechanism and motor-generator which delivered 30 volts of DC. The bar units could also be installed in the basement if desired, in which case grillwork was installed in the floor above them to transmit the sound; or they could be installed in the music room where the console was and concealed behind panelling or whatever was desired. The units were all connected by cables, usually armored with interwoven wire strands to protect them from damage. If all the machinery and also the bar units were to be placed in the basement, the space required would be approximately that of a modest bedroom.

Melvin L Severy circa 1915
Melvin L Severy circa 1915

The final phase of the development of the Choralcelo was the rewiring of the controls so that upper partials could be at the command of the Choralcelist and thus the potential of the instrument was greatly expanded because infinite variations and combinations were now available. The attempt to produce a completely new, unique instrument of this complexity in such a short period of time… the original factory closed in 1917 because of the war… was a monumental undertaking, and the multiplicity of the directions one might take was daunting. After all, the piano metamorphosed over several centuries, and other instruments have done the same. Experiments were conducted with reeds. A magnificent, large double bass unit having steel ribbons instead of individual strings was developed… there was a remote full-sized string unit which could be remotely placed… A variation of the interrupter mechanism was developed using brass discs instead of the earlier cylinders. There were twelve discs, each with six tracks, rotating at speeds determined by the gearing. All of these inventions, some of which were superseded by later ones, required designing, engineering, machining.. the investment was astronomical. In today’s money it amounted to many hundreds of millions of dollars. The instruments themselves were expensive, by today’s standards costing about a half million.

There were about one hundred built, many of them being installed in the music rooms of the wealthy. There were some that were in theatres to accompany silent films… Filene’s in Boston had two, one in the restaurant. Lord and Taylor in New York, and Marshall Field in Chicago, among others, featured Choralcelos, as did several hotels. There were even two on yachts.

The effort was a daunting task but great strides had been made by the time WWI broke out… materials were no longer available and as a result, the factory closed. Farrington and several of the most devoted men involved remained active in several locations, Cleveland, Chicago, Port Chester, Connecticut, and New York among them. The last activity was a demonstration studio in New York City, but another world war broke out and the studio closed in 1942.”

Choralcelo Patent Files

‘The Choralcelo, a Wonderful Electric Piano’

 ‘The Electrical Experimenter’ Magazine, USA. March 1916

This Marvelous Electrically Operated and Controlled Musical Instrument is More Than a Piano – It Produces Sustained Notes of the Lowest and Highest Register, Over a Range Heretofore Unattainable, and, Moreover, is Played Like a Regular Piano

In India, far away, as the popular song goes, the natives are content to regale themselves musically with plaintiff notes given forth by a goat skin stretched over the end of a hollowed log, upon which the musician beats a tune with the flat of his hand.

The music of the caveman was the wind is sighing through the trees, accompanied by the rustle of the leaves. Even they wanted to express themselves in a harmonious manner, hence the drum, the horn and other crude instruments of musical expression.

Then we may possibly expect some marked advances in our musical culture and education since the advent of the “Choralcelo,” despite the prophecies of those who take a pessimistic view of life in general.

The piano becomes a tongue-tied infant beside the latest masterpiece of the musician’s art. At times its notes thunder forth and seem to shake the very earth itself, and then again they may be subdued to an elusive softness like unto the faint notes of a distant church choir.

But what is it? How is it accomplished? What is the result of many years of untiring labor on the part of several of the cleverest men of the world? What is it upon which a fortune that would ransom a king has been spent? The Choralcelo!

The Choralcelo, the most wonderful musical instrument ever thought out by the human mind, is like nothing else the world of music has ever known. This masterpiece reproduces any piece of music in any form of instrument, from a string to a flute; not only does it reproduce them, but the notes emitted by it are sustained, pure and sweet, which is entirely different from the ones produced by the instruments that are in present use.

Practically all the musical instruments, previous to the invention of the Choralcelo, carry into the tone which they produce certain impurities which arise from the manner in which they are caused to vibrate. The violin interrupts the free vibration of the string by the grating rub of the bow. The piano adds the noise that results from the blow of the hammer on the string – while the organ mingles the breathiness of its air current with the pure vibrations of the column of air in the pipe. In like manner all instruments employing extraneous contacts to start the vibration destroy the purity of the note produced. And as they seek to amplify the tone they have produced they increase the intrusion and false sounds. The soft pedal of the piano, the swell-box of the organ, the mute of the violin, are just so many outrages on the purity of the tone.

The Choralcelo, by the very means which it employs in producing the tones, is freed from all obstructions. Vibration without contact, involving perfect freedom of vibration, and thus the Choralcelo gives all the natural overtones and harmonics; rich – full – pure and perfect, thus opening to the musician wonderful possibilities of expression and emotional power of which he possibly never dreamed.

The manner in which this result is accomplished is one of wonder. It is the subtle pull of the electromagnet which now achieves pure tone production. These electromagnets are caused to act directly upon the strings of the instrument.

The most delicate graduation of tone power can be produced by the mere variation of the strength of an electric current, and not by smothering devices which the present form of instrument employs. The tone, therefore, retains all its original purity through all vibrations and intensity, something that has been impossible heretofore.

We will next inspect the mechanism employed to perform these wonders. It may be stated that the vibrating elements are caused to oscillate by means of a pulsating electric current sent through an electromagnet acting on the vibrating membrane.

The machine which beaks up continually the electric current into a series of waves is really the “heart” of the Choralcelo. The operating device consists essentially of a series of metal discs having a certain number of insulating segments inserted into their peripheries. These discs are arranged to revolve at a fixed speed. Silver-tipped brushes are so placed that they will bear upon the revolving discs. It will thus be seen that in order to produce the fundamental periodicity of any given “string”, it is only necessary to rotate a disc containing a certain number of segments at the correct speed.

A large number of combinations are possible through the manipulation of a few keys, which correspond to the stops of an organ, and such a keyboard is clearly shown at Fig. 1. This resembles a piano, and it really is one, with additional keys and pedals. The pedals are used to vary the strength of the current sent through the electro-magnets.

A tremolo effect is given by means of a slow speed interrupter giving a pulsating current at a few revolutions per second. The instrument which produces this effect is depicted on the right of Fig. 2, while the one towards the left reproduces tones representing a flute. The regulation piano tone is produced with the usual percussion hammers, which may be thrown into or out of action by the pressure of a key. The staccato notes of the piano may be struck upon strings already vibrating with the pulsating current. Thus sustained notes of a higher pitch are produced upon the string.

A piano which employs both the electro-magnets and hammers is clearly shown on the left of Fig. 3. Note the large number of wires which are employed for connecting the various for connecting the various magnet coils. It is an engineering feat in itself to even make and wire the various circuits.

Marvelously sweet tones are produced by vibrating pieces of brass, wood and aluminum. In fact, any resonant body susceptible to vibration may be made to emit tones. In order to cause these bodies to vibrate, it is necessary to place within them a small piece of iron, so that the electro-magnets may attract them. Instruments that are operated by this method are depicted in Fig. 3. The one toward the right is an instrument that imitates a flute. The electro-magnets are placed underneath the tubes, which are made out of wood and act as resonating chambers. The magnets are caused to act on iron discs mounted at the lower end of the tube. Another style of flute instrument is illustrated in Fig. 4. This employs a different variety of tubes, ranging from a very high tone to a very low one. The smaller pipes give the latter tone, while the larger ones the former.

The instrument shown in the center of Fig. 3 illustrates a brass chime. The tones are produced by hammers, each of the tubes being supplied by one. These are operated by electro-magnets, as perceived in the upper bracket of the stand. These are also connected to the same keyboard.

The very deep tones of an organ are produced by vibrating diaphragms placed beneath metal horns. A pair of electromagnets are held a minute distance away from the diaphragm and serve to vibrate the latter when the pulsating current is applied. The volume of the tones is powerful and is very pleasant although it is very low. By increasing the power in the electro-magnets, the strength of the tones is so much increased that it is almost impossible to imagine the effect.

“Echo” combinations may also be installed without limit wherever their effect may be most beautiful at any distance from the master instrument. Thus the greatest cathedral may be filled with a glory of sound. The tower may be used to flood the surrounding country with the same divine melody. It may also be carried to the quiet cloister and to the private room. An instrument played in one place may repeat its music elsewhere.

The Choralcelo was developed and its wonderful basic principle discovered by Melvin L. Severy of Arlington, Mass., and George B. Sinclair. These savants have been working for twelve years to bring this musical instrument up to the perfection which it has reached today. One cannot predict its possibilities or limits as it is really still in its early stages of development. 5‘The Choralcelo, a Wonderful Electric Piano’
‘The Electrical Experimenter’ Magazine, USA. March 1916


  • 1
    “First Choralcelo Concert Proves Highly Successful,” The Musical Age (1 May 1909)
  • 2
    The Musical Age. New York, May 1st 1909.
  • 3
    Sheets, Arian, (2013) Choralcelo, Grove Music Online. Retrieved 27 Nov. 2021, from
  • 4
    Jenkins, C.W (2002) The Choralcelo, Amica Bulletin. AMICA International
    Automatic Musical Instrument Collectors’ Association
  • 5
    ‘The Choralcelo, a Wonderful Electric Piano’
    ‘The Electrical Experimenter’ Magazine, USA. March 1916
H.Trabandt: ‘Das Choralcelo’ ZI,xxix (1910)-‘Das Choralcelo als Konzertinstrument’ ZI xxx (1910)

Amica Bulletin. Volume 45, Number 4 August/September 2008

The New England Magazine.

‘An Early Electro-Magnetic Experiment’ Edith Borroff, College Music Symposium Vol. 19, No. 1 (Spring, 1979), pp. 54-59

The ‘Rangertone Organ’. Richard H.Ranger, USA, 1932

Richard Ranger at the Rangertone Organ
Richard Ranger at the Rangertone Organ

The Rangertone Organ was a large electronic tone-wheel based organ developed by the electronics engineer and pioneer of audio recording Richard Ranger in the 1930’s. The instrument was marketed by Ranger from his own company ‘Rangertone Incorporated’ on Verona Ave. in Newark, NJ. Very few of the instruments were sold, one of which was installed at the Recital hall of Skinner Hall of Music, Vassar College. After the failure to sell the instrument Ranger went on to develop a series of high fidelity phonograph devices that never went into production. During WW2 Ranger spent time investigating German electronic equipment for the US Army and it was here that he picked up and removed for his own use the German AEG Magnetophone tape recorder. Ranger returned to the U.S. and in 1947 announced his new Rangertone Tape recorder, based on the Magnetophone, which finally gave the Rangertone Inc the financial success it needed until squeezed out of the domestic market by larger companies such as Ampex.

AEG Magnetophone. The first tape recorder, Germany 1944
Richard Ranger with the  wireless facsimile system
Richard Ranger with the wireless facsimile system. in 1924, Richard Ranger invented the wireless photoradiogram, or transoceanic radio facsimile, the forerunner of today’s fax machines. A photograph of President Calvin Coolidge sent from New York to London in November 1924 became the first photo picture reproduced by transoceanic radio facsimile.
The Rangertone Organ was one of the early tone wheel organs, similar to the Hammond Organ and much earlier Telharmonium (1906). Uniquely, the Rangertone Organ had its pitch stability controlled by tuning forks, therefore it was possible to change the temperament by changing the tuning of the forks. Timbre was controlled by push-buttons to the right of the keyboard, and/or by switching between six different amplifier/speaker combinations, which had different tremolo and tonal qualities.The original version was a huge machine, with more than 150 valves. A portable single-keyboard model was built for concert performance.
Ranger made the first public demonstration of his huge  ‘pipeless organ’ at Newark, New Jersey in 1931.
Press telegram announcing Ranger's new instrument
Press telegram announcing Ranger’s new instrument in 1931
Pitch controls of the Rangertone Organ
Pitch controls of the Rangertone Organ

“Ranger’s apparatus consisted essentially of twelve separate sets of motor-driven alternators precisely maintained at given rotational speeds, by tuning-fork control apparatus. One of these sets of alternators, as shown in Fig. 5, generated all the required C’s; another all the C sharps; another the D’s, and so forth. From these alternators he obtained all the desired fundamentals and their true harmonic frequencies for the tempered scale. Timbre control switches selected the partials and their amplitudes for any desired tone quality. Amplifiers were, of course, used with reproducers to translate the feeble audio currents into sound.

Ranger’s improvements over the basic work of Cahill were made possible by the advent of the vacuum tube. For example, he provides means for automatic selection of different amplifiers, for different simultaneously produced tones, to prevent cross modulation in a single amplifier; means for avoiding keying transients, for accentuating high or low frequencies, for restricting tremolo to specific components of a complex tone, and at different tremolo rates, means to provide glissando effects, for regulating the temperament, for providing damped wave trains in simulation of percussive tones, and numerous other details.”

Proceedings of the institute of Radio Engineers November 1936 Volume 24

Richard Howland Ranger 1899, Indianapolis, Indiana, d 1961
Richard Howland Ranger 1899, Indianapolis, Indiana, d 1961


Biographicall details by: Dr. David L. Morton, Jr. Research Historian IEEE Center for the History of Electrical Engineering
Proceedings of the institute of Radio Engineers November 1936 Volume 24
ELECTRONIC MUSIC AND INSTRUMENTS. By Benjamin F. Miessner. (Miessner Inventions, Inc., Millburn, New Jersey)

The ‘Hammond Organ’. Laurens Hammond, USA, 1935

The original Hammond Organ was Designed and built by the ex-watchmaker Laurens Hammond and  John M Hanert in April 1935. Hammond set up his ‘Hammond Organ Company’ in Evanston, Illinois to produce electronic organs for the ‘leisure market’ and in doing so created one of the most popular and enduring electronic instruments ever built.
Hammond’s machine was designed using technology that relates directly to Cahill’s ‘Telharmonium’ of 1900, but, on a much smaller scale. The Hammond organ generated sounds in the same way as the Telharmonium, the tone wheel – The tone generator assembly consisted of an AC synchronous motor connected to a gear train which drove a series of tone wheels, each of which rotated adjacent to a magnet and coil assembly. The number of bumps on each wheel in combination with the rotational speed determined the pitch produced by a particular tone wheel assembly. The pitches approximate even-tempered tuning.
This method of creating tones was maintained  until the mid 1960’s when transistors replaced tone wheels
The Hammond had a unique drawbar system of additive timbre synthesis (again a development of the Telharmonium) and stable intonation – a perennial problem with electronic instruments of the time. A note on the organ consisted of the fundamental and a number of harmonics, or multiples of that frequency. In the Hammond organ, the fundamental and up to eight harmonics were available and were controlled by means of drawbars and preset keys or buttons.A Hammond console organ included two 61-key manuals; the lower, or Great, and upper, or Swell, and a pedal board consisting of 25 keys. The concert models had a 32-key pedalboard. Hammond also patented an electromechanical reverb device using the helical torsion of a coiled spring, widely copied in later electronic instruments.
As well as being a successful home entertainment instrument, The Hammond Organ became popular with Jazz, Blues and Rock musicians up until the late 1970’s and was also used by ‘serious’ musicians such as Karlheinz Stockhausen in “Mikrophonie II”

Hammond patent documents

The ‘Telharmonium’ or ‘Dynamophone’ Thaddeus Cahill, USA 1897

The dual manual of the MkII Telharmonium. Gunter's Magazine June 1907
The dual manual of the MkII Telharmonium. Gunter’s Magazine June 1907

In 1895 Thaddeus Cahill submitted his first patent for the Telharmonium “The Art of and Apparatus for Generating and Distributing Music Electrically”. The Telharmonium can be considered the first significant electronic musical instrument and was a method of electro-magnetically synthesising and distributing music over the new telephone networks of victorian America.

Thaddeus Cahill's patent documents for the first Telharmonium 1896
Thaddeus Cahill’s patent documents for the first Telharmonium of 1897 showing the arrangement of rotor alternators and rheostat brushes.

This first patent was initially rejected by the patent office because the “plan contained principles and practices found in other patented devices”. Cahill, a trained lawyer, eventually succeeded in having his patent accepted in 1897.

The first design of the instrument set out the principles of the ‘Telharmonium’ or ‘Dynamophone’ that would be developed by Cahill over the next twenty years. Cahill’s vision was to create a universal ’perfect instrument’; an instrument that could produce absolutely perfect tones, mechanically controlled with scientific certainty. The Telharmonium would allow the player to combine the sustain of a pipe organ with the expression of a piano, the musical intensity of a violin with polyphony of a string section and the timbre and power of wind instruments with the chord ability of an organ. Having corrected the ‘defects’ of these traditional instruments the superior Telharmonium would render them obsolete.

Thaddeus Cahill's patent documents for the first Telharmonium of 1897
Thaddeus Cahill’s patent documents for the first Telharmonium of 1897 showing tone rotor shafts

The other innovative aspect of Cahill’s design was that he proposed to distribute the electronic musical output of the instrument over the newly established telephone network to subscribers at home or in hotels and public spaces; hence the name ‘Telharmonium’ – ‘Telegraphic Harmony’. This was partly due to the fact that the only way of hearing the instrument in the pre-amplifier and loudspeaker era was via an acoustically amplified telephone receiver.


In 1885 Hermann Helmholtz’s ‘On the Sensations of Tone’ (1862) appeared in English translation and had an immediate and profound impact on scientific and musical thinking. Helmholtz defined the concept that a tone was composed of a single fundamental sound which, combined with a set of higher sounds, gave each musical tone a unique quality or timbre – and that these tones were a collection of ‘pure’ sine tone. Cahill’s reasoning was that the ‘perfect instrument’ could be built to created sine tones that could be combined to recreate the qualities of existing instruments without their ‘defects’.

The German edition of Helmholtz's ‘On the Sensations of Tone’ (1862)
The German edition of Helmholtz’s ‘On the Sensations of Tone’ (1862)

The idea of transmitting music over he telegraphic or Telephone network was not new. Cahill was well aware of previous inventions and experiments with Telegraphic music.

Soemmerring's musical telegraph
Soemmerring’s musical telegraph of 1809

As far back as 1809,the Prussian anthropologist, paleontologist and inventor Samuel Thomas Soemmerring created an electrical telegraph that triggered an array of tuned bells from a distance of several kilometres. This experiment was originally as an intended as an investigation into human consciousness and perception but led to speculation about the possibilities of transmitting music electronically over great distances.

Poster for the Budapest Telefonhírmondó
Poster for the Budapest Telefonhirmondo

In 1893 the Hungarian engineer and inventor Tivadar Puskás established the ‘Telefonhírmondó’ or ‘Telephone Herald’ a type of telephone based newspaper that broadcast music and news over the telephone network in Budapest to as many as 91,000 subscribers which continued (in tandem with a radio service) until World War II when the wire network was destroyed.


In Paris, Clément Ader created the ‘Théâtrophone’ a type of early binaural or stereo audio transmission of music and theatre in 1881 which ran until it was superseded by radio in 1931 and similarly, in London in 1895, the ‘Electrophone’ service distributed music hall and light music to an audience of subscribers.

But probably the biggest technical influence on Cahill was Elisha Gray’s ‘Musical Telegraph’ of 1874. Gray, one of the inventors of the telephone, had developed a way of  transmitting pitched tones over a long distance telegraph network using electromagnetically controlled vibrating metal reeds. Gray had originally intended to use this as a way of sending multiple messages over a network ( a predecessor of multiplex signals)  and had created a musical keyboard instrument to promote his ideas. It was the similarity of Gray’s work to Cahill’s initial concept that led to the rejection of Cahill’s first patent and in response Cahill was scathing about Gray’s instrument declaring that the Musical Telegraph was:

“practically useless. No person of taste or culture could be supposed to derive any enjoyment from music rendered in poor, harsh tones, with uneven power, and absolutely without expression or variation.”

…and that Gray’s patented machine was unable to produce sine waves or complex harmonics of the Telharmonium;

“…do not produce undulations of current; they produce sharp, violent (tones). (The device) unavoidably adds to the partials desired many which are injurious — so many, that his patent . . . seems … to wholly break down.”

Cahill restructured his patent to accentuate the differences between his invention and that of Elisha Gray – nevertheless, Gray’s ‘Musical Telegraph’ clearly had a major influence on Cahill’s new instrument.

Scientific American vol 96 no10 9th March 1907
The Telharmonium in the ‘Scientific American’ vol 96 #10 9th March 1907

The ‘Telharmonium’ or ‘Dynamaphone’

Cahill’s major criticisms of Gray’s ‘Musical Telegraph’ was that by using electromagnetically oscillating metal reeds, Gray’s instrument only had enough power to be heard at close range to a telephone receiver and, the Musical Telegraph’s oscillators could only create harsh, simple tones that lacked character and expression. Cahill’s proposal was to generate complex mixtures of sine tones using multiple electrical dynamos that would be powerful enough to be audible to an audience from a distance.

A single tone wheel generator
A single tone wheel generator with eight alternators.

The core of his invention was the tone wheel; essentially a rotor with variably shaped alternators  that spun within a magnetic field (The early versions used rheotomes; a set of brushes that contacted the rotor as it spun.) to generate a tone. Each tone wheel was composed of the fundamental tone and six ascending partials. The first model consisted of a mainframe of twelve identical rotors each of the twelve pitch-rotors carried seven fundamental alternators, six third-partial alternators, and five fifth-partial alternators. These rotors were spun at the relevant speed by a belt driven motor, giving the instrument a six octave range. This arrangement gave the Telharmonium two tuning systems; one being a pure harmonic series used for building the timbre of each note, and the other, an equal tempered scale used for combining notes into a scale.

Diagram showing frequencies of the Telharmonium alternators. image from ‘Magic Music from the Telharmonium’ By Reynold Weidenaar

The output quality of the tone wheels – especially with the rheotome versions – was harsh and unpleasant. The sound quality was softened by passing the signal through a series of secondary induction coils that filtered the harshness from the sound to a tone approximating a sine wave. (These induction could could also be controlled by the velocity of the keyboard, allowing the musicians a complex level of expressive influence over the tone.). Cahill was able to dispense with these purifying circuits in later models after perfecting rotor teeth cutting techniques to provide an almost pure sinusoidal output.

The number of partials for each fundamental could be controlled with familiar organ like stops allowing the instrument to imitate orchestral instruments. In this way, the Telharmonium was the first additive synthesiser; recreating instrumental timbres by adding and mixing harmonics.

The idiosyncratic 3 manual version of the MkI Telharmonium
The idiosyncratic 3 manual version of the MkI Telharmonium
Dual manual of the MkII Telharmonium. Gunters Magazine 1907.

Less familiar was the keyboard arrangement; for the second Telharmonium, Cahill hired the pianist Edwin Hall Pierce to develop a repertoire for the instrument as well as create sounds from the multiple harmonics. Pierce, with Cahill, also defined the unusually complex keyboard arrangement. Because the Telharmonium mechanically created notes using exact divisions that equated to just intonation, Pierce decided to use three sets of keyboards (two or sometimes four in later models) that allowed for thirty six keys per octave (over the three keyboards) – this meant that instead of the usual black and white key layout, the manual consisted of alternate black and white keys and the player had to learn to play over three manuals to achieve an equal tempered scale. Despite this nightmarish keyboard-complexity the Telharmonium had the unique ability – if required – to play over a variety of intonations.

Patent documents of the Telharmoinium
Patent documents of the Telharmoinium

A unique clutch like device allowed the player to control expression using key velocity as well as with a foot pedal. The resulting sound was fed through the wire network and streamed to the audience through large, six-foot acoustic horns of various designs– Cahill experimented with numerous horn designs using different thicknesses of wood, metal carbon and paper to acquire the right range of tones.

Acoustically resonating speaker of the Telharmonium.
Acoustically resonating speaker of the Telharmonium. 1917 patent.

For the Telharmonium to be audible beyond a telephone receiver it needed a much more current than the standard telephone; the output power from the Telharmonium’s alternators was as much as 15,000 watts and around 1 amp at the receiver – compared to a telephone receiver designed for currents as low as six ten-trillionths of an amp. This power did allow the Telharmonium to be audible to an audience but caused interference with the New York telephone network and needed a huge amount of electricity to keep it running.

Tone rotors of the MkII Telharmonium in the basement of Telhamronic Hall c 1907
Two of the tone rotors of the MkII Telharmonium in the basement of Telhamronic Hall circa 1906. Image from McCLure’s Magazine 1906

The sound of the Telharmonium

The first description of the sound of the Telharmonium was from Ray Stannard Baker writing for McClure’s magazine describing a demonstration of the Washington MkI Telharmonium at the Hotel Hamilton;

“The first impression the music makes upon the listener is its singular difference from any music ever heard before : in the fullness, roundness, completeness, of its tones. And truly it is different and more perfect: but strangely enough, while it possesses ranges of tones all its own, it can be made to imitate closely other musical instruments: the flute, oboe, bugle, French horn and ‘cello best of all, the piano and violin not as yet so perfectly. Ask the players for fife music and they play Dixie for you with the squealing of the pipes deceptively perfect. Indeed, the performer upon this marvelous machine, as I shall explain later, can “build up” any sort of tone he wishes : he can produce the perfect note of the flute or the imperfect note of the piano — though the present machine is not adapted to the production of all sorts of music, as future and more extensive machines may be.

After several selections had been given I was conscious of a subtle change in the music. Dr. Cahill said: “Mr. Harris has taken Mr. Pierce’s place.”

It is quite as possible, indeed, to distinguish the individuality of the players upon this instrument as it is upon the piano or violin. The machine responds perfectly to the skill and emotion of the player; he gets out of it what he puts into it: so that the music is as much a human production as though the player performed upon a piano. In an hour’s time we had many selections, varying all the way from Bach and Schubert to the ” Arkansas Traveler ” and a popular Stein song. One duet was played by Mr. Pierce and Mr. Schultz. The present machine is best adapted to the higher class of music. It does not produce with any great success the rattlebang of rag-time which is perhaps an advantage”

Ray Stannard Baker writing in McClure’s Magazine.  1903

And Thomas Commerford Martin writing in the Outlook on the 5 May ;

“A skillful performer upon the telharmonium can make it blare like a trumpet, snarl like a bassoon, warble like a flute, or sing like a violin. Four or five performers, playing in concert, will ultimately be able, it is believed, to produce an effect closely approaching that of a full orchestra ; for each bank of keys is furnished with a set of stops somewhat like those of an organ, by means of which it can be made to produce tones almost if not quite identical with those of any family of instruments. At one keyboard one player can play the part of the strings ; at another a second player can reproduce the tones of the oboe family ; at another a third player can reproduce the tones of the brass ; and so on. And each player is able in an instant to modify or transform the quality of tone which he is producing.

Of course there are limitations in this power to imitate instruments. In the violin tone on the telharmonium there is nothing of resin and catgut ; in the tone of the French horn there is not the occasional break characteristic of that instrument. On the other hand, the quality of tone in the telharmonium is capable of infinite variation.- Instrumental effects are possible on it which have never before been heard.”

The Telharmonic Hall, New York City circa 1906
An audience at Telharmonic hall enjoying a concert of Telharmonic music played through carbon-arc lamps.
An audience at Telharmonic hall enjoying a concert of Telharmonic music played through carbon-arc lamps. Gunter’s Magazine June 1907
A gospel service accompanied by the Telharmonium at Telharmonic Hall. Gunter's Magazine June 1907
A gospel service accompanied by the Telharmonium at Telharmonic Hall. Gunter’s Magazine June 1907
The future of music. A photograph from Gunter's Magazine June 1907 that imagines the future of electronic music played to households through carbon-arc lamps
The future of music. A photograph from Gunter’s Magazine June 1907 that imagines the future of electronic music played to households through carbon-arc lamps

Established at the Telharmonic Hall Cahill’s New York Electric Music Co. put on several seasons of Telharmonic music from 1906 – including guided tours of the basement machinery. The repertoire consisted of popular light classical works that emphasised the instrument’s range and flexibility. The audience listed to the music using a variety of horns and speakers including music fed into a series of carbon arc lamps that oscillated with the electronic signal giving an audio and light show (this phenomena had been explored by the British physicist William Duddell and was used in his ‘Singing Arc’ instrument of 1899)

Programm for Telharmonic Hall concerts
Programm for the Telharmonic Hall concerts

Ray Stannard Baker in McClure’s magazine in 1903 also contemplated the effect the Telharmonium would have on music and the listener arguing that it would ‘democratise’ music:

“As the machine is developed, and as the players become more expert, we may enter upon quite a new era of music, what ma)’ be called, indeed, the democracy of music. We cannot really herald the complete dominance of democracy until we have good music, great pictures, and the best books at the command of every citizen. Museums, galleries, and process printing have gone far towards bringing that equal opportunity of all citizens for the enjoyment of great pictures, which is the dream of the social philosopher. Free libraries have placed the best and rarest books at the command of any man who wishes to use them. But music, by its nature ephemeral and costly of production, has not so easily submitted itself to such democracy of enjoyment. Poor music may be had anywhere: good music is it is hived up in grand opera houses, and supported by playing upon the social vanity of the rich. It is a pastime for society. To this fact, indeed, may be traced the slow development, much deplored by critics, of musical taste in this country.”

The Three Telharmoniums

In all Cahill designed and built three versions of the Telharmonium (with five patents);

The, MkI version, as described in his 1897 patent, Cahill built by hand in his laboratory in Washington and, weighing a mere 14,000lbs was essentially a working prototype designed to raise capital for a planned full version .

The Cabot St Mill, Hollyoke, Mass as it is today.
The Cabot St Mill, Hollyoke, Mass as it is today.

Once enough interest had been generated to finance the development of the Telharmonium Cahill and his associated moved to the Cabot St Mill in Holyoke, Mass. where construction of the much larger MkII commenced in 1902. the MkII was constructed by a workforce of fifty engineers, grinders, reamers, assemblers and other workers under the guidance of Cahill.

Keyboard players of the MkII Telharmonium
Keyboard players of the MkII Telharmonium

The MkII consisted of  eight 11” steel shafts bearing a total of 145 alternators. The 60-foot mainframe was built of 18” steel girders set on brick foundations. Ten switchboard panels contained almost 2,000 switches. The whole apparatus weighed 200 tons and cost $200,000 and assumed the proportions and appearance of a power station generator.

The switchboard and tone circuits of the MkII

It was this version that was disassembled in 1906 and transported to by railroad to be installed at the ‘Telharmonic hall’ on 39th Street and Broadway New York City where it was previewed to an audience of nine hundred people. The MkII Telharmonium remained in NYC for another four years giving regular concerts and ‘broadcasts’ at the Telharmonic Hall and other fashionable venues across the city. Despite it’s initial success the subscriber business foundered after the 1907 financial panic and Telharmonic Hall closed in 1910.

Audience at the Cafe Martin where the Telharmonium was broadcast
Audience at the Cafe Martin, New York City where the Telharmonium was broadcast

After the collapse of the ‘Telharmonic Hall’ business, Cahill regained control of the rights to his invention and stoically rebuilt and refined the design to create the final MkIII version back at the Cabot St mill. The Mk III, again weighing 200 tons but with a number of significant improvements including new alternator designs and a standard keyboard for a tempered scale,  was installed in the basement of a building on west 56th st NYC. It was here that the Telharmonium made it’s final debut in Feb 1912 streaming music to the Chapter room of Carnegie Hall. Despite Cahill’s improvements and tireless promotion of the instrument, ‘Telharmony’ had lost the novelty value that sustained public interest six years previously and subscribers failed to materialise. Cahill finally filed for bankruptcy in 1914. The  MkII and III Telharmoniums were sold for scrap. The remains of the first Telharmonium were kept  by Cahill’s brother Arthur but were also scrapped after his death in 1958.


Dr. Thaddeus Cahill’s system of generating music at a central station in the form of electrical oscillations, and of transmitting these oscillations by means of wires to any desired point, where they are rendered audible by means of an ordinary telephone receiver or a speaking arc, is now embodied in a working plant situated in the heart of New York. Although this apparatus constitutes b.ut a portion of a plant that may ultimately assume very remarkable dimensions, and although it has limitations imposed by its size, the results obtained are so promising, that many applications have been made by prospective subscribers for connection with the central station. When a larger number of · generators and keyboards is installed, as they doubtless will be in due time, there is no reason why the telharmonium, as the invention is called, should not give the subscribers all the pleasures of a full symphony orchestra whenever they wish to enjoy them. At present ‘ very beautiful effects are secured on a . less elaborate scale, but in eveI\ly way comparable with those of a good quintet.. And several additional keyboards now in building at Dr. Cahill’s works at Holyoke, Mass., where the New York plant was built, are nearing completion, and will probably be in service at Broadway and Thirty-ninth Street in the course of another month or two.

Perhaps the feature which most astonishes the technically Uninformed man when Dr. Cahill’s invention is first exhibited to him is the fact that music in the ordinary sense of the word, in other words, rhythmic vibrations of the air, is not produced at the central station. The vibrant notes of the flute, mingled with the clarinet or viol-like tones which are heard at the receiving end of the wire, spring from no musical instrument whatever. Nowhere is anything like a telephone transmitter used, although the electrical oscillations which are sent to the receiver and there translated into audible vibrations are quite like those set up in an ordinary telephone circuit, except that they are enormously more powerful.

Briefly summed up, Dr. Cahill’s wonderful invention consists in generating electrical oscillations corresponding in period with the acoustic vibrations of the various elemental tones desired, in synthesizing from th ese electrical vibrations the different notes and chords required, and in rendering the sYnthesized electrical vibrations audible by a translating device.

In the New York plant the electrical vibrations are produced by 144 alternating dynamos of the inductor type, having frequencies that vary from 40 to 4,000 cycles. These alternators are arranged in eight sections or panels, each inductor being mounted on an ll-inch steel shaft. One inductor dynamo is used for each note of the musical scale, each generator producing as many electrical vibrations per second as there are aerial vibrations in that note of the musical scale for which it stands. The fixed or stator part of each dynamo carries both the field and armature windings ; the rotors are carried on shafts geared together, the number of teeth ( pole pieces) on the gear wheels corresponding with the number of frequencies to be ob-. tained. Because the rotors are geared together, the frequencies are fixed and tuning is unnecessary. The alternators are controlled each by a key in a keyboard upon which the musician plays. Each key serves to make and break the main eircuit from seven alternators, not directly, but through the medium of plunger relay magnets wound with layers of enameled wire. Only feeble and harmless currents are needed to control the relay magnets, by which the task of making and breaking the currents from the main circuits is r’eally performed. No appreciable ‘ time elapses between the depression of a key and the closing of a main alternating circuit, so that the keyboard is as responsive and sensitive as that of a piano. The elemental notes generated by the . 144 dynamos cannot alone be used to produce the most pleasing musical effects.

Why this should be so becomes apparent from a consideration of some Simple principles in acoustics. If a wire be stretched between two points A and B (see the accompanying diagram) and plucked or struck, it will vibrate above and below the line A, B and give what is known as a fundamental tone. This fundamental tone is without distinctive musical character or timbre, and would sound the same in all instruments, so that one could not distinguish whether it came from a violin or a piano. In addition to its fundamental vibration between its pOints of attachment, the string undergoes a series of sub-vibrations above and below its own normal curve, which it will pass at certain points, nodes, dividi????g it into equal parts. Thus in the accompanying sketch, A, 0, B and A, D, B represent the fundamental Vibrations, and A, E, 0, F, B, the first sub-vibration intersecting the fundamental vibration at the node 0. Again, the string may vibrate in three parts, four parts, five parts, etc. The effect of the sub-vibrations is added to the effect of the fundamental vibration, and their total effect is heard in the distinctive quality or “tone Color,” as it is called, of the particular instrument played. The sub-vibrations are known as the upper partials or overtones, and generally speaking, they are harmonious with one another and with the fundamental tone. That very elusive and uncertain quality called timbre is dependent entirely upon these overtones. By properly controlling the blending of the overtones and the elemental tones, it ought to be possible to. imitate the characteristic timbre of any musical instrument. This Dr. Cahill has in a large measure succeeded in accomplishing.

“Tone mixing,” as this building up of harmonious notes and chords is called, is effected in the telharmonium by superposing the simple or sinusoidal waves of the alternators. By means of bus-bars the oscillations of the ground tones are all brought together in one circuit, those of the first partials in another circuit, those of the second partials in a third circuit, etc. The actual blending is done by passing the various oscillations through a series of transformers. In order to understand how a chord is blended, we must begin at the keyboard. As soon as the performer depresses his keys, the bus-bars electrically superpose the ground tone currents , through the primaries of closed-iron magnetic circuit transformers, the secondaries of which are jained in circuit with impedance rheostats governing the strength of the currents, which rheostats are controlled from the keyboard by means of stops. Similarly the bus-bars superpose the first, second, third, and other desired partials in separate circuits. The composite ground-tone a’nd overtone oscillations thus produced in the secondaries of the transformers are next passed through the primaries of an open-iron magnetic circuit transformer, in the secondary circuit of which a current is produced composed of all the ground tone and overtone frequencies of the particular chord under consideration. This secondary current is in turn passed through the primary of an air-core transformer, and the resultant secondary current is converted by telephone receivers or speaking arcs into the musical chord desired.

In order to listen to this musical chord, the telephone receiver is not held to the ear. It would be bad for the ear if it were, when a loud note is sounded. The current of the receiver is literally thousands, and at times millions of times stronger, measured in watts, than those to which an ordinary telephone receiver responds. Whereas less than six tenmillionths of an ampere are sufficient to produce a response from an ordinary telephone receiver, a current of an ampere is sometimes used in the Cahill system for an instant when loud tones are produced.

The composition or quality of a note or chord is controlled by eight rheostats called stops. By skillful manipulation of the stop rheostats, it is possible to obtain very accurate imitations of the wood-winds and several other orchestral instruments. Imitation, however, is hardly the right word ; for the notes are built up of exactly the same components as the tones which come from the reaJ instruments. Furthermore, beautiful effects are obtained that cannot be produced on any existing instrument. These stop rheostats control merely the timbre or quality of the music produced. Fluctuations in volume are produced by “expression rheostats.” Both stop and expression rheostats are constituted by impedance coils, differing however in mechanical construction. The stop rheostats are manipulated very much like the stops of an organ, and the expression rheostats like the swell. Unlike an organ swell, however, the expression rheostats are used not only for producing captivating crescendos and diminuendos of individual notes and chords, but also in reproducing the peculiar singing tremolo of the violin and ‘cello.

The rather complex system of transformers described serves not merely to blend partials with ground tones, but also to purify the vibrations corresponding with the different sets of partials by purging them of their harsher components. The air core transformers, fur thermore, permit the selection of voltages according to the resistance which the final current will encounter. Inasmuch as each keyboard controls ground-tone and overtone mixing devices, it is possible to produce notes of the same timbre or of different timbres. Excellent orchestral effects can, therefore, be obtained by causing the one keyboard to sound wind instruments, such as oboes, flutes, clarinets, or horns, and the other to sound the tones of the violin or other stringed instruments.

From this necessarily cursory consideration of the telharmonium, it is evident that the music is initiated as electrical vibrations, distributed in the form of electricity, and finally converted into aerial vibrations at a thousand different places separated hundreds of miles, it may be. No musical instruments in the sense in which we understand the word are used. Not a string, reed, or pipe is anywhere to be found. The vibrations produced by the performers’ playing are wholly electrical, and not until they reach the telephone receiver can they be heard. The telephone reo ceiver acts for us as a kind of electrical ear to hear oscillations to which our own ears are insensitive. When Mark Twain heard the telharmonium, he fancifully suggested that the military parade’ of the future would be a more beautifully rhythmic procession than our present pageants. The usual military bands heading the various regiments and playing marches, not in unison, although the same in time, will give place to musical arcs disposed along the line of march, all crashing out their stntins in perfect time. The soldiers who will march in that future parade win all hear the blare of invisible electrical trumpets and horns at the same moment; they will all raise their left feet at exactly the same instant, just as if they were but one company.

So far as the capabilities of the telharmonium are concerned, it may be stated that the New York installation is able to supply ten thousan-d subscribers, or more, with music of moderate volume at widely remote places. The very remarkable and rapid development of the invention has been thus eloquently set forth by Prof. A. S. McAllister in an article published in the Electrical World :

“From Hero, who first proposed to utilize the motive power of steam, to Watt’s first successful engine, was almost two thousand years. And between the proposal of Hero and the accGmplishment of Watt many inventors in different countries made ineffective attempts to attain the goal desired. From Huyghens’s proposal of an explosive motor to Otto’s successful machine two centuries elapsed, with scores of patents in the different countries of Europe. So from Sir Humphry Davy’s experimental arc to the Brush and Edison arc lighting machines” three-quarters of a century elapsed, during which scores of inventors in different countries endeavored to solve the problem in vain. Similar remarks apply to the progress of most great inventions, electri· cal and mechanical. But the process of producing music from dynamos has been carried from the first conception to the successful working machine by one man-Thaddeus Cahill-in a few years. And when one hears the plant at Thirty-ninth Street and Broadway, with its musical tones already equaling, if not surpassing, the instruments of the orchestra, one wonders what cannot be expected in a few years to come when the inventor will have had time to do his best, and when his work in all its details will be known ·to the world and open to improvement by others, and when musicians will have learned to use the new powers which electricity is placing at their command. Clearly the world has, through the wonderful powers of the electrical forces and the skillful use made of them by Dr. Cahill, a new music, a music which can be produced in many thousand places simultaneously, and which in its very infancy seems destined to surpass in sympathy and responsiveness-in artistic worth-the existing music of pipe and string, the evolution of many centuries.”

From ‘Scientific American’ vol 96 #10 9th March 1907

The end of the Telharmonium

The reason for the failure of Cahill’s project were numerous. The machine itself was impossibly expensive; about $1 million was spent from 1897 to 1914 on the project ( approximately $30 million in today’s value) and it was unlikely that a subscriber business model would have ever covered the costs, let alone make a profit – and, even if Cahill had found enough subscribers, he’d have to have built a power plant to generate enough power.

The output power of the Telharmonium caused great disruption of the New York Telephone network, angering telephone subscribers and even interrupting the Stock Exchange, which resulted eventually in AT&T refusing to co-operate in supporting Cahill’s instrument.

The Telharmonium was also a victim of an age of rapid technical advances; Lee De Forest began experimenting with radio transmissions as early as 1906 (which included transmissions of the Telharmonium) and by around 1914 wireless radio broadcasts had spelled the end for wire broadcasting.

The technology developed by Cahill did however continue. In 1934 the American watchmaker Laurens Hammond developed a new electronic home organ which was essentially a miniaturised Telharmonium

“Thaddeus Cahill, developer of the Telharmonium, was . . . endowed with the ability to think big. Although not strictly electronic (it predated the invention of the vacuum tube by about a decade), the Telharmonium embodied many basic principles that have been used in the electronic music medium: the generation of pitched tones from alternating electricity, the addition of harmonics to determine tone color (additive synthe- sis), and a touch sensitive keyboard to shape the sounds and control their strengths. This first polyphonic, touch sensitive music synthesizer remained in service in New York for only a few years . . . The basic idea was resurrected again in the 1930s in an instrument that was somewhat more of a commercial success: the Hammond Organ.”

Robert A. Moog,”ElectronicMusic,”Journal of the Audio Engineering Society, October/November 1977, 25:10/11, 856.

Baker’s article on the Telharmonium for McClure’s Magazine, ‘New Music for an Old World,’ came to the attention of the Italian virtuoso classical pianist and critical intellectual Ferruccio Busoni who enthused about the instrument in his 1907 ‘Sketch of a New Aesthetic of Music’ which proposed a new music constructed of infinite gradations of tone, surpassing the 12 note scale and traditional orchestration:

“The question is important and imperious, how and on what are these tones are to be produced. Fortunately, while busied with this essay, I received from American direct and authentic intelligence which solves the problem in a simple manner. I refer to an invention by Dr. Thaddeus Cahill. He has constructed a comprehensive apparatus which makes it possible to transform an electric current into fixed and mathematically exact number of variations.”

and, directly inspired by Cahill’s instrument– though he never actually heard it:

 “Who has not dreamt that he could not float on air? And firmly believed his dream to be reality? Let us take thought, how music may be restored to its primitive, natural essence; let us free it from archectonic, acoustic and aesthetic dogmas; let it be pure invention and sentiment, in harmonies, in forms, in tone-colours (for invention and sentiment are not the prerogative of melody alone); let it follow the line of the rainbow and vie with the clouds in breaking sunbeams; let Music be naught else than Nature mirrored by and reflected from the human breast; for it is sounding air and floats above and beyond the air; within Man himself as universally and absolutely as in Creation entire…”

Busoni’s manifesto of 1907 inspired his students including a young Edgard Varèse as well as a whole new school of microtonal instrument designers and musicians. Varèse on arriving at New York in 1915 went to see the instrument in it’s final days and was not much impressed:

“[Busoni] was very much interested in the electrical instruments we began to hear about and I remember particularly one he had read of in an American magazine, called the Dynamophone, invented by a Dr. Thaddeus Cahill, which I later saw demonstrated in New York and was disappointed.”

Louise Varèse, Varèse: A Looking-Glass Diary, Vol. I, New York: W.W. Norton and Company, 1972, 50;

Inside the Telharmonium:

Mark Twain (Clemens) remembers the Telharmonium:

“I recall two pleasant social events of that winter: one a little party given at the Clemenses’ home on New-Year’s Eve, with charades and storytelling and music. It was the music feature of this party that was distinctive; it was supplied by wire through an invention known as the telharmonium which, it was believed, would revolutionise musical entertainment in such places as hotels, and to some extent in private houses. The music came over the regular telephone wire, and was delivered through a series of horns or megaphones — similar to those used for phonographs — the playing being done, meanwhile, by skilled performers at the central station. Just why the telharmonium has not made good its promises of popularity I do not know. Clemens was filled with enthusiasm over the idea. He made a speech a little before midnight, in which he told how he had generally been enthusiastic about inventions which had turned out more or less well in about equal proportions. He did not dwell on the failures, but he told how he had been the first to use a typewriter for manuscript work; how he had been one of the earliest users of the fountain- pen; how he had installed the first telephone ever used in a private house, and how the audience now would have a demonstration of the first telharmonium music so employed. It was just about the stroke of midnight when he finished, and a moment later the horns began to play chimes and “Auld Lang Syne” and “America”.”Mark Twain: A Biography,Albert Bigelow Paine (New York: Harper & Brothers, 1912), 1364-1365

Patent Documents


‘MAGIC MUSIC FROM THE TELHARMONIUM’ Reynold Weidenaar Scarecrow Press 800/642-6420; 301/459-3366
Holmes, Thomas B. Electronic and Experimental Music. New York: Scribner, 1985. pp. 32-41
‘Scientific American’ vol 96 #10 9th March 1907
‘ New Music for an Old World’ McClure’s magazine. v.27 1906 May-Oct.
“The Telharmonium: A History of the First Music Synthesizer,” review by Thomas L Rhea. Computer Music Journal, vol. 12 #3, 1988
Gunter’s Magazine [v5 #5, June 1907] The Home Publishing Company, 503-622pp