Armand Givelet , the engineer and physicist at the radio laboratory at the Eiffel Tower in Paris produced his first instrument the ‘Clavier à Lampes’ in 1927 as a way of solving audio technical problems at the radio station. Because microphones of the time were of poor quality, it was impossible to record or broadcast decent quality sound. Givelet’s response was to build an electronic organ that could be directly injected into the transmitter without using microphones. The resulting instrument, the ‘Clavier à Lampes’ was a monophonic vacuum tube keyboard instrument.
The ‘Clavier à Lampes’ was premiered in Paris in 1927 and taken on tour to the United States starting with the Trocadero Theatre in Philadelphia on June 9th 1927.
Images of the ‘Clavier à Lampes
Armand Givelet Biographical notes
Armand Givelet (born:21 07 1889 Reims France – died:09 11 1963 La Varenne St-Hilaire, St-Maur-des-Fossés) was originally an engineer in the French military during the First World War but soon recognised the potential of Lee De Forest’s triode technology. He founded the first Radio Club in France and the T.S.F. engineering school. Givelet became a recognised authority on radio technology and inventor who held many patents for radio and broadcast equipment as well as his work with electromechanical (tone-wheel) and valve based electronic musical instruments; His particular contribution w as a stabilised audio oscillator that used much less power than traditional triode circuitry.
Givelet’s first complete instrument was the The monophonic “Piano Radio-électrique” unveiled in 1927. A meeting with the organ Builder Eloi Coupleux in early 1929 began a life-long collaboration that produced some of the earliest electronic organs – designed primarily for church and religious music. The largest of the Coupleux-Givelet instruments was built for “Le Poste-Parisien” – withs 200 oscillator tubes producing 70 different timbres or stops. Despite their unique features, The Coupleux-Givelet organs were rapidly made obsolete by much smaller and cheaper organs such as the Hammond Organ. Only four organs were sold by Coupleux-frères to churches in France.
Givelet also wrote theatrical works under the pseudonym Ch. de Puymordant.
Olivier Carpentier ‘L’Aventure industrielle des frères Coupleux, 1900-1935’ Préface de Douglas Heffer, éditions de l’Inoui, 2004.
La Vie et les ondes : l’oeuvre de Georges Lakhovsky / Michel Adam et Armand Givelet, 
The Choralcelo (“heavenly Voices”) was a hybrid electronic and electro-acoustic instrument conceived as a commercial high-end domestic organ, sold to wealthy owners of large country houses in the USA. The Choralcelo was designed and developed by Melvin 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’.
Severy was a versatile inventor, engineer musician, composer and author. Before the Choralcelo, Severy’s inventions already included patents for printing presses, solar heating systems, a camera, fluid drives, and many others.The Choralcelo was developed by Severy from 1888 until 1909. Te instrument was first presented to the public on the 27th April 1909 at the Boston Symphony Hall,in Boston, Mass. At it’s unveiling the Choralcelo was accompanied by A soprano voice and about forty members of the Boston Symphony Orchestra and was said to have been ‘enthusiastically received’ by some of ‘Boston’s best known families’.
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 electro-magnets 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”
The Musical Age.New York, May 1st 1909.
The company was taken over in 1918 by Farrington. C. Donahue & A. Hoffman (in some reports claimed as its inventor). At least six of the instruments were sold and continued to be used up unit the 1950’s. Two working examples of the instruments are known to have survived in the USA one at Ruthmere Mansion in Elkhart, Indiana.The Choralcelo was a direct contemporary of the Telharmonium, though not as big, was still a huge instrument using a similar electromagnetic tone wheel sound generation to the Telharmonium used in the ‘organ’ section of the instrument as well as a set of electromagnetically operated 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
Promotional material from the Choralcelo company
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 fund raiser and invested his own fortune in the work.There had been many efforts at strengthening or lengthening the tone of piano strings electrically.
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.
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.
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
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 electro-magnet which now achieves pure tone production. These electro-magnets 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 electro-magnet 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 electro-magnets 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.
H.Trabandt: ‘Das Choralcelo’ ZI,xxix (1910)-‘Das Choralcelo als Konzertinstrument’ ZI xxx (1910)
The French electrical engineer, mechanic and doll modeller, René Bertrand, who had been experimenting with electronic instruments as early as 1914, was a long time friend and collaborator with Edgard Varèse and with Varèse’s support Bertrand developed the “Dynaphone” (not to be confused with Cahill’s “Dynamophone” or “Telharmonium“).
The Dynaphone was a portable, monophonic instrument controlled not with a keyboard but played with a pitch-lever and volume switch. The instrument was semi-circular in shape with a diameter 0f 30 cm played on top of a table. The Dynaphone belonged to a family of dial-operated non keyboard electronic instruments developed around the 1930’s such as Mager’s ‘Spharaphon‘. The right hand controlled the pitch using a circular dial on a calibrated disc (cardboard cut-out templates of music could be inserted). The total rotation of the dial was equal to seven octaves but only the five highest or lowest could be selected at any one time by the means of a switch, giving an overlap of three octaves common to both ranges.
Additional vibrato effects could be added by moving the right hand to and fro slightly and the machine also included a push button for articulating the sound. The left hand controlled the volume and timbre – described as similar to a cello, low flute, saxophone or french horn. The Dynaphone generated sound by the by-now standard method of a heterodyning vacuum tube pair, originally used in Leon Termen’s ‘Theremin‘.
A later development of the Dynaphone (known as the ” Radio-electric-organ” used a five octave keyboard on which the note played could be doubled at the fifth and octave. The first public demonstration of the instrument in 1928 was a performance of Ernest Fromaigeat’s ‘Variations Caractéristiques’ for six Dynophones and later in ‘Roses de Metal’ a ballet by the swiss composer Arthur Honegger
In 1932 Varèse applied to the Guggenheim memorial fund for a grant towards continuing the development of the Dynaphone:
“…..The Dynaphone (invented 1927-28) is a musical instrument of electrical oscillations similar to the Theremin, Givelet and Martenot electrical instruments. But its principal and operation are entirely different, the resemblance being only superficial. The technical results i look for are as follows:
To obtain pure fundamentals
By means of loading the fundamentals with certain series of harmonics to obtain timbres which will produce new sounds.
To speculate on the new sounds that the combination of two or more interfering Dynaphones would create if combined as one instrument.
To increase the range of the instrument to reach the highest frequencies which no other instrument can give, together with adequate intensity.
The practical result of our work will be a new instrument which will be adequate to the creative needs of musician and musicologist…..”
Despite Varèse’s assertions, the Dynaphone was not distinctly different from its close competitors and the Guggenheim Foundation did not sponsor Bertrands work despite several further attempts by Varèse.
In 1941, Edgard Varèse, in the hope to resume his collaboration with Léon Theremin, wrote him the letter reported below (courtesy of Olivia Mattis ), but the inventor wasn’t able to read it until 1989, when musicologist Olivia Mattis, during an interview with Theremin (first emerged from Russia after 51 years), presented a copy of it. The letter is dated May 5, 1941.
Dear Professor Theremin,
On my return from the West in October I tried to get in touch with you. I wanted very much to see you again and to learn of the progress of your work. I was sorry – on my account – that you had left New York. I hope that you have been able to go on with your experiments in sound and that new discoveries have rewarded your efforts.
I have just begun a work in which an important part is given to a large chorus and with it I want to use several of your instruments – augmenting their range as in those I used for my Equatorial – especially in the high range. Would you be so kind as to let me know if it is possible to procure these and where … and in case of modifications in what they consist. Also if you have conceived or constructed new ones would you let me have a detailed description of their character and use. I don’t want to write any more for the old Man-power instruments and am handicapped by the lack of adequate electrical instruments for which I now conceive my music.
Mr. Fediushine has kindly offered to forward this letter to you. Please let me hear rom you as soon as possible. With cordial greetings and best wishes in which my wife joins me,
P.S. If any of your assistants or collaborators are continuing your work in New York would you kindly put me in touch with them.
Edgard Varèse L.E.Gratia: ‘La Musique des Ondes éthérées’ , Les ménestrel, xc (1928)
‘L’Afrique du Nord illustrée’ 05-05-1928.
‘Le Petit Parisien – journal quotidien du soir’ 1928 04 24
‘René Bertrand’s Dynaphone: Roses de Metal by Arthur Honegger’. GloryLynn Foster Van Duren. 1983.
Invented by the French engineer Pierre Toulon aided by the electronic engineer Krugg Bass, the Cellulophone (“Cellule Photo-électrique”) made it’s debut as a prototype in France in 1927. The Cellulophone was an electro-optical tone generator instrument resembling an electronic organ controlled by two eight octave keyboards and a foot pedal board.
The sound was created by passing a light beam through slits in a vari-speed rotating disk. The single spinning disk was cut with a number of equidistant slits (54 slits for the lowest note) with different shaped masks to create varied timbres. The disks masked a light beam that flashed through the slits and on to a photoelectric cell, the speed of the rotating disk therefore determining the frequency of the output signal from a single vacuum tube oscillator.
Toulon’s Cellulophone won the Prix jean Bares in 1933:
Second prize (2,500 francs) was awarded to Mr.. Pierre Toulon, a father of three children and consulting engineer of the Electrical School , who made a large number of inventions, among which include “the relay arc” whose principle is applied in instruments referred to as “Thyratrons” and “Spark-gap convertors”, the latter enabling flattening and straightening of even high powered electrical currents.
Mr. Toulon also invented a device called “Cellulophone” – a musical instrument keyboard developed by the Pleyel company, which is an organ extremely reduced in size.
One disk was used for all the notes of each octave therefore notes whose frequencies could not be generated by an integral number were out of tune. This system however gave the unique and unusual possibility of having a different timbres for each octave. The Cellulophone was one of a generation of instruments in the 1920-30’s using a photo-electric sound generation method; other examples being the “Licht-ton Orgel” , the “Photona” and the “Radio Organ of a Trillion Tones”. The increased sophistication and reliability of post war electronic circuitry marked the decline of light based synthesis after the 1940’s except for a few pioneers such as Daphne Oram who used a similar sytem not only to synthesise sounds but to sequence sounds.
Pierre Toulon proposed in the 1930’s a related technique of speech synthesis using fragments of optical film mounted on a rotating drum.
Extract from ‘La Revue hebdomadaire : romans, histoire, voyages.’ Paris, March 1928 which describes various new electronic instruments of the period including the Cellulophone:
LA MUSIQUE RADIOPHONIQUE
Les concerts du professeur Theremin. Une expérience d’acoustique fort instructive. Battements électriques. Où interviennentles lampes à trois électrodes de la T. S. F. Le principe de l’éthérophone. Un précurseur. Piano etorgues radio électriques. Le cellulophone. Conclusion. On a beaucoup parlé ces derniers temps d’une rénovation de l’art musical par l’emploi d’instruments de musique utilisant la merveilleuse souplesse des ondes hertziennes. Les concerts donnés cet hiver à Paris par le professeur Léo Theremin, de Léningrad, ont attiré un nombreux public. Il n’est pas douteux que l’idée d’utiliser les ondes hertziennes à la production des sons puisse constituer une innovation heureuse. Essayons donc de décrire le merveilleux appareil du professeur Theremin et d’en faire comprendre le fonctionnement.
L’explication paraîtra très simple à tous les sans-filistes. Quant à mes autres lecteurs, s’ils veulent bien me prêter quelque attention, je suis certain qu’ils saisiront tout aussi aisément le principe de la musique radiophonique. Rappelons tout d’abord une expérience d’acoustique que chacun peut répéter, pourvu qu’il possède chez lui quelque instrument de musique.
Tout le monde sait que le son est produit par les vibrations de la matière et qu’il nous paraît d’autant plus aigu que les vibrations sont plus rapides. Lorsqu’on fixel’extrémité d’une tige d’acier, une lame de fleuret par exemple, dans un étau, et qu’après l’avoir écartée desa position on l’abandonne à elle-même, elle entre en vibration et produit un son, d’abord très grave, maisqui monte de plus en plus au fur et à mesure qu’on raccourcit la lame, ce qui augmente le nombre des oscillations par seconde. Les sons les plus graves que l’on puisse entendre correspondent environ à 30 vibrations par seconde, et les sons les plus aigus à 40 000. Entre ces limites s’étend toute la gamme des sons perceptibles.
Mettons en bran le deux diapasons identiques, donnant par exemple chacun le la normal, l’un d’eux ayant été désaccordé par un peu de cire fixée sur l’une des branches. Le diapason normal effectuant 435 vibrations par seconde, celui qui a été désaccordé en donnera par exemple 432. Dans ces conditions, lorsque les deux diapasons fonctionnent en même temps, on perçoit dans le son d’ensemble des renforcements et des affaiblissements sucessifs,des sortes de hou, hou, hou, répétés régulièrement etqu’on appelle des battements. L’expérience a permis de constater que le nombre deces hou, hou, hou. par seconde est exactement égal à la différence entre les nombres de vibrations par seconde que donnent séparément les deux diapasons, soit ici 435 diminué de 432. Il y a donc trois battements par seconde. Le phénomène est général. Chaque fois qu’on produit simultanément, au moyen d’appareils quelconques, deux séries de mouvements vibratoires dont les nombres d’oscillations par seconde sont différents, l’ensemble donne lieu à des renforcements et à des affaiblissements successifs,à des battements. Or les ondes hertziennes résultent d’une sorte de mouvement vibratoire d’un milieu hypothétique qu’on suppose répandu partout et auquel on a donné l’antique nom d’éther. Dans les ondes, dites entretenues, qu’utilise la radiophonie, les vibrations sont très régulières mais extrêmement rapides. Elles se produisent à raison de quelques centaines de mille par seconde. Envoyées directement dans un téléphone, ces ondes seraient sans actionsur lui, car à supposer qu’elles fussent capables de faire vibrer, suivant un rythme de quelques centaines de mille par seconde, la membrane du téléphone, nous serions incapables de percevoir des vibrations aussi rapides, pour les quelles notre oreille est atteinte d’une surdité absolue. Mais émettons simultanément, au moyen de deux appareils différents, deux séries d’ondes hertziennes, les unes, pour fixer les idées, à raison de ioo ooo vibrations par seconde, et les autres, à raison de 99 000. Leur production simultanée donnera naissance à des battements électriques, à des renforcements suivis d’affaiblissements des ondes hertziennes, dont le nombre par seconde sera égal à 100,000 diminué de 90,000. Et à ces battements électriques qui se produisent ainsi à raison de 1,000 par seconde, le téléphone peut être rendu sensible. Sa membrane oscillant à raison de r 000 vibrations par second eémettra un son aisément perceptible. Si donc, l’une des deux séries d’ondes demeurant invariable et se produisant toujours à la fréquence 100 000, nous avons le moyen de faire varier la fréquence de l’autre série d’ondes et de la rendre égale par exemple à 99,500, à 99,400, à 99,300. le nombre des battements, toujours égal à la différence des fréquences associées, sera successivement 500, 600, 700. par seconde. Le téléphone actionné par les battements fournira un son deplus en plus aigu, correspondant successivement à 500, 600, 700. vibrations par seconde. Et c’est là tout le secret de l’éthérophone. Des ondes hertziennes sont produites à la fréquence moyenne de 300 ooo vibrations par seconde par deux générateurs appelés hétérodynes. Si les deux séries d’ondes sont légèrement désaccordées, elles donnent lieu à des battements électriques qui, agissant dans un haut-parleur à la manière habituellement utilisée dans les réceptions radiophoniques, en actionnent la membrane et produisent un son. De la boîte où sont enfermées les deux hétérodynes émergent une tige métallique verticale jouant le rôled’antenne, et une spirale en fil de cuivre placée horizontal ement sur le côté. Le fonctionnement de l’appareil consiste à faire varier les constantes électriques de l’un edes deux séries d’ondes en approchant la main droitede l’antenne verticale et la main gauche de la spirale. Le premier mouvement fait varier la fréquence des battements et, par conséquent, détermine la hauteur de lanote le second mouvement agit sur l’amplitude des ondes et par suite sur l’intensité du son. De ces deux mouvements, le premier, qui doit suivre les notes de la partition musicale, est évidemment le plus compliqué etest de ce chef dévolu à la main droite le second est réservéà la main gauche en raison de sa simplicité.
L’idée qui est à la base de l’éthérophone n’est pas nouvelle. Dès 1917, les ingénieurs français travaillant au laboratoire de la tour Eiffel avaient songé à tirer un parti musical des battements radio électriques dont nous venons de parler. M. Armand Givelet, vice-président du Radio-Club de France, avait eu l’idée de marquer à lacraie sur le cadran du condensateur d’hétérodyne le réglage correspondant aux différentes notes de la gamme. En tournant rapidement ce condensateur variable et en arrêtant brusquement l’aiguille sur les repères du cadran, il était parvenu assez facilement à jouer des mélodies populaires simples. C’était, en somme, exactement le principe de l’éthérophone. Il a suffi de perfectionner quelques détails pour obtenir un appareil permettant deproduire des effets véritablement artistiques.
D’ailleurs, M. A. Grivelet a réalisé, il y a quelques années, le premier piano radio électrique. On a pu voircet instrument exposé récemment au premier Salon des Sciences et des Arts, au Grand Palais des Champs Élysées. Chaque note est produite par un circuit séparé, engendrant les vibrations sans qu’aient à intervenir des battements. De son côté, M. Bertrand a construit sous le nom d’orgue radio électrique un appareil d’un principe tout à fait analogue à celui du professeur Theremin, qui utiliseles battements électriques de deux hétérogynes, et dans lequel le son est diffusé par un haut-parleur de grand modèle. La variation de la hauteur du son est produite par la commande d’une manette qui se déplace devant un cadran comportant une gamme de trois octaves.
Le Cellulophone de M. Pierre Toulon n’est pas moins curieux. Son principe est tout différent. Il utilise la propriétédes cellules photo électriques, sortes de piles qui donnent naissance à un courant lorsqu’elles reçoivent un faisceau de lumière. En envoyant sur une cellule, non un éclairage continu, mais un éclairage intermittent qu’on peut réaliser en interposant entre la source lumineuse etla cellule un disque tournant perforé, la pile produit une succession de courants instantanés dont le nombre par seconde dépend du nombre des trous que porte le disqueet de sa vitesse de rotation. Envoyés dans un haut parleur,ces courants le font vibrer avec la même fréquence. La hauteur de la note musicale dépend ainsi du nombre de trous que porte le disque et de sa vitesse derotation, le timbre étant déterminé par la forme de cestrous. On conçoit qu’on puisse modifier à volonté la hauteur et le timbre, et obtenir des effets musicaux très variés.
Il serait difficile de prédire l’avenir qui est réservé aux appareils de musique radio électrique. Indiquons seulement qu’ils ont permis d’obtenir des effets artistiques très intéressants, et il ne serait pas surprenant que,grâce à eux, la musique, cette forme si élevée et si expressive de l’art qui a très peu évolué depuis des siècles,entrât dans une voie entièrement nouvelle.
From Le Genie Civil February 7, 1928
Donhauser, P.: Elektrische Klangmaschinen.Die in Deutschland und Österreich Pionierzeit, Boehlau Vienna 2007.