A Personal story of Music and Technologies...

Godfried-Willem RAES


 A survey on 25 years of activity in the realm of experimental musical instrument contruction by the author, a Flemish composer and full-time professor of experimental composition at the Royal Conservatory of Music in Ghent, Belgium. Both areas of acoustical design and electronic analog/digital designs are discussed.

This article was first published (in a slightly shortened version) by Leonardo, 1993.

Article text:

When I wrote my first real piece using live electronics in 1967, an electronic 'conductor' was used for a small orchestra, allowing the musicians to play in individually different, yet strictly related, tempi. It was titled 'Logos' and caused a scandal at the conservatory. It was also at the origin of the Logos group, since the Conservatory threw us out! The study of classical instruments has left me with a serious hangover ever since. Despite all my explorations and attempts, these instruments remain strange objects that always left me unsatisfied to a certain extent. They have a language of their own. For the realization of that kind of music, these instruments attained a certain level of optimalisation, but in relation to my own music, they were mostly obstinate and unwilling.

Around 1968, when Logos started, it was a time when anti-authoritarism was daily gaining popularity among intellectuals and artists. It was marked by a radical denial of serialism and postserialism, by an emphasis on collective work and life, and on a refusal of artificially separated artistic disciplines. Art, and music too, had to be accessible for everyone, neither by vulgarization nor by a lowering of its standards, nor by simplification, but by opening it to active participation by as many people as possible.

We considered creativity as an unjustifiable privilege that only could be positively developed by demolishing it as the privilege of professional artmakers. Now it seems it was in the air: in England, Scratch Orchestra also started along similar lines shortly after Logos, in June of 1969, and even in the U.S, there were a couple of initiatives along similar paths. The real meaning of these trends of the late sixties can be seen in what we would call their will to conquer the power over and in the relation between music and its producers. All obstacles upholding authoritarism of music-production and reproduction were avoided as much as possible and broke down. The resulting production was open to the participation of everyone interested, a form of music characterized by non-elitism and very strong egalitarianism. This tendency was highly in contrast with very institutionalized post-serial trends, with their cultivation of specialization and generalizable principles of style, instrumental and notational techniques etc.

Back then, next to our basic traditional instruments (cello, violin, oboe, piano and a lot of percussion) our instrumentation included quite a few electroacoustic and experimental instruments which we designed for our use: electroacoustic monochords and clavichords, amplified and tuned bicycle wheels, electronic generators, electronic modulation equipment which as a sounding totality made us quite distinct from our English counterparts, and which may suggest some resemblance with contemporary ensembles such as Musica Elettronica Viva, or even more, the Sonic Arts Union. But comparison with these and other groups, also demonstrates very fundamental differences. Personally I always experienced electronic sound as a caricature of acoustic sound. A musical comic, since it is a one-dimensionalised simplification of acoustical sound. All reliable analog and purely electronic sound-generating systems, as used in synthesizers and electronic music studios all over the world, are based on the hoary Helmholtz paradigm. These systems are fundamentally always one-dimensional and pure periodic vibrating systems, and for that reason, when confronted with their acoustical counterparts, they necessarily resemble caricatures of the latter.

Analog electronics

 My own work in electronic music started from this consciousness, and still does, even if nowadays I'm mostly working and experimenting with digital hard- and software. I have always used electronics for its quality of caricature, without the slightest attempt to artificially camoflage this, as most composers do.

As I went on developing these insights further and became more familiar with these ideas and their physical consequences, my experimental instrument building took some very different paths. The first was towards the demystification of electronic sound, besides other things, by the design of small and simple play-synthesizers, "synthelogs," of which I built about 50. These Synthelogs contain almost everything essential to electronic synthesizers: i.c. V.C.O.'s, noise generator, oneshot circuits with ADSR-control and external inputs.

Another deliberate attempt at demystification was to cease using large and elaborate electronic equipment for public concerts. Until 1972 Logos had been using a voltage controlled bank of 12 oscillators (the "Dodekadent"), a voltage controlled bank of another 12 amplifiers with ADSR (the 'Rhytmisator') quadraphonic outputs and spacialisation possibilities, 200/300 controllable knobs and buttons, external wiring and hookups. This complex looking instrumental decorum usually overwhelmed the audience, and we were often queried about the equipment more than about what we were trying to achieve musically. To be admired for relatively simple things about which the audience lacks the most basic notions and insight was contrary to some of the fundamental ideological principles the Logos-people shared then: to make experimental music accessible with means mostly available to everybody, and not only to professionals. Although entirely homemade, the apparatus was impressive, and lent us a kind of authority and power. This embarrassing and unintended situation led us to give up the use of eye-catching live electronics in our concerts. All the equipment 'stayed home' in our studio where it continued to evolve.

 Sound Sculpture

 It was around that time that Lieve De Pelsmaeker (a Flemish ceramist who died in 1984) had asked me to collaborate with her and to supply her rather monumental sculptures with proper sound. For these ceramic soundobjects and soundsculpture, I built a series of electronic circuits incorporated in the sculptures and which could be influenced and played by any visitors who might be so tactilly moticated. The manifold cavities within the ceramic had their own resonances. These were my first series of "sonomobiles". Since the public could affect them and play around with them, they were'nt mystifying as the huge electronic concert equipment. Reduced to the degree of toys, the public felt free to explore and enjoy them.

Another uncomfortable aspect of pure electronic sound generation, had to do with the character of the relation between the instrument and the instrumentalist. With acoustical instruments one can assume a narrow physical connection and involvement between the physical effort of the musician at one end and the acoustical result at the other. The many variables of physical involvement are always present as long as acoustical or electroacoustic instruments are used, but hardly ever in their electronic counterparts. I looked in the direction of direct playing of electronics by immediate manipulation of the circuitry. By applying electricity to one's own body, it was possible to physically inject it into the circuits, causing a kind of bodily contact with specially designed instruments. Meanwhile, my friend Michel Waisvisz, was similarly preoccupied in Holland, and his research led to the design of his crackle-boxes. These I particularly appreciated for here the otherwise very unelectronic principle of 'no move, no sound' found a perfect realization. Nevertheless the produced sound itself remained strongly marked by its electronic one-dimensionality.

However, in my own work the pure electronic device as an instrument lessened in importance as I concentrated more on the electronic device as composition: resistors, capacitors, and chips, composed into a design and realization of functioning technical systems. Many of the music theater compositions of the Logos-group are composed around one specifically designed device or machine. ("Sotto Voce", "For Synthelog", "Montage", "Timeframes", "Holosound", "Soundtrack", etc., although within the last years the borderline between electric and electroacoustic machines became more obscured as I started to incorporate 3-dimensional objects into fully digital electronic oscillating circuits).

The first series of "sonomobiles" led me to the construction of my triptych of musical automates/machines: "Bellenorgel", "Beltotem", and "Beltelefoon" (1973-80). They are soundsculptures in the full sense: not real musical instruments, and not playable.

"Bellenorgel" is a full automatic programmable musicmachine, using digital logic circuits taken from telephone systems. In a certain way 'Bellenorgel' can be considered a rule-based composing machine.

In "Beltotem", the sounding result depends on the way it is addressed to by the spectators: they can talk to it, or shout at it, and the "Beltotem" will correspondingly respond.

"Beltelefoon", the last machine of the triptych, is a musical fruitmachine, a gambling automat. These three machines all originate from acoustical signaling devices: electrical bells, clocks, buzzers, sirens, horns, bip-bips and beeps... all signaling devices usually used to alert people to action.


 Parallel to my electronic work but more related to Logos-group's instrumental needs, I've developed many other electroacoustic and purely acoustic instruments. The electroacoustic ones often reveal a close connection to those made by the English music maker Hugh Davies and the Americans Richard Lerman and Dan Senn, and all are based on what I call "sonorous microscopy". "New sounds" are not produced, but vibrations of physical objects not accessible for the normal ear are brought into the common acoustical realm via specific miking techniques, and thereby made available for musical uses and users.

"Dudafoon" (1975/1976), is made of a bikewheel, springs, metal scrapobjects, mounted on a wooden case which functions also as a loudspeaker enclosure combined with six transducers working according to a different principle. Since no external control knob is provided on the instrument and the amplification internal and preset, "Dudafoon" may be played just like any normal acoustic instrument. The name is derived from Duchamp, because of the bikewheel, DAda and FOON (-phone).

For my "Fingerbox" (1983), I decided to omit internal power amplification to reduce the volume and weight of my instruments as much as possible.

"Fingerbox" holds no less than 22 sound transducers next to a subminiature version of an optocontrolled synthelog. Electronic and electroacoustic soundgenerators are brought together. (A combination I've used in 1974 for an instrument ironically named "VCS 2000"). These instruments also proved very successful in music education for beginners with their easy accessibility and the enormous flexibility of the sounds produced. Their working principles led to further explorations in instrument building and the construction of soundobjects, and they greatly helped Logos to achieve the realisation of one of out fundamental premises: the elaboration of a noncompetitive music culture.

This instrumentbuilding also showed me the way to develop an alternative for a system of music education that had become entirely fossillized and that allowed me to work on an alternative repertoire for Logos based on different sets of instruments and equipment. The electroacoustic instruments, which I developed mainly to the needs of my frequent international touring with Moniek Darge, are like my purely electronic designs and very specific to a precise compositional concept.

The technical principles of these homemade instruments I consider intrinsic to the subject of the composition. And this nearly automatically leads to a multimedia compositional approach. "Timeframes" and "Holosound" are good illustrations of this. For "Timeframes", a machine was designed to record acoustical sounds and send them, after manual playback into a group of objects (long springs) that would thus be set into vibration. The game here with the chronology of the acoustic events is purely a consequence of the machinery used, and thus of the compositoric idea. The set up and use of the equipment is theatrical, and this intrinsic theatricality provides an essential insight into the composed apparative structure.

This multimedia aspect of my work is not merely a strange complement to intrinsically different elements, but a further development of properties and elements that are a given a priori. Their design and playing technique become theatrical elements, and instead of hiding this (which would be a dishonest mystification), I worked it out.

On this road it becomes obvious not to adhere to the mere consequence of the multimedia aspect, but to develop it polyphonically with the acoustical element. This multimedia exercise demands some pluridisciplinary competence, and its ideal environment is a collective, such as Logos, where these pieces achieve their stage design most often with Moniek Darge, a specialist in fine arts and performance art. The scores dissolve into "works in progress" which continually change at each concert.


 Many of these aspects became even more pronounced in "Holosound". This piece uses two distinct 3-dimensional oscillating systems. Three receivers and one transducer for ultrasound (for between 40 and 200 kHz), are set up to circumscribe a large tetrahedron. When a moving object or a body enters this area, the emitted soundwave is reflected by the moving surface, causing a Doppler-shift of the frequency: This differential tone is audible after frequency demodulation in receivers designed for this purpose. Since there are three receivers, (the minimum required for a holosonic effect) the differential tones demodulated by each will vary because the velocity of the movement is a function of its direction as seen from the receivers. The pitches result solely from the speed of the movement and the amplitude only on the size of the moving surface: A moving finger effects a "pp" whereas moving all your chest produces a "ff". Now I had a real invisible instrument, capable of translating movement into sound directly and in a musically relevant way. As we developed the stage piece, Moniek Darge fully exploited the appearance of magic and witchcraft in the electronic setup. We performed this duo all over the world. This system is also designed so that it can become a very complex oscillating system, using the differential tones for frequency-modulation of the ultrasonic carrier frequency. The sound is further patched to trigger a second multi-dimensional oscillating system for the controll of which I designed a dedicated microcomputer.

For "Holosound", the computer-controlled vibrations come from spring steel blades, about 0.02- 0.01mm. thick and about 2 meters long. Although, the technique of controlled aperiodic oscillation, can utilize just about any object. For example, suppose the receiving transducer picks up 100 vibrations a second. These vibrations are then counted and the computer takes this value and performs some simple and programmable arithmetic operations: add 20, divide by 3, subtract 4... With this mostly programmable modulo-n divider system, the recalculated signal is output to the emitting transducer forcing the attached object into a new motion pattern. The loop is closed and the feedback values are constantly recalculated to prevent any new periodic waveforms.

In the late eighties, I constructed a midi-controller using this technology. Microcontrollers implementing basic neural nets were used for fast parallel processing of the data. [more about holosound...]


 The musical event "Soundtrack" was realized in the summer of '82. It uses a trajectory about 3 km. long, diagonally crossing the center of a city. Environmental sounds are recorded by the "Soundtracker", all at walking velocity, a highly 'subjective' speed that modulated continuously the recording. In the small time the tape reached the playback head on the machine, the speed had changed, and this modulated playback signal reproduced and transmitted by radio to the soundtrack of a simultaneously happening video-recording of the event.

This recorded soundtrack was played back at the same time, and left behind as a track through the city. The tape was stuck on the street itself with markings of time and date, or, in parks and on soft soil, buried whenever possible.

Which medium could we claim here? Was it still a composition? Had it anything to do with music? No other work went as far as this "Soundtrack", and not only its being a street happening. In 1977-78 we had developed "Singing-Bikes", another street event, using about 2O bicycles supplied with large plastic tubes, individually tuned to fundamentals derived from one single "master" fundamental. These resonating tubes were driven by matched loudspeakers at their extremities, connected through a passive diode network to the bicycles' dynamos and produced a pulsating current with a frequency proportional to the speed of the bicycle. The bikes followed each other through the streets at a fairly constant pace, but the score had the last bike accelerate and overtake all the others. The result was highly musical: a huge cluster in which the ever changing just intonation tones predominate.

Pure acoustics

 A third part of my instrument-making is investigation into the realm of "pure acoustics", which originated from using non-orthodox techniques on traditional instruments. Instead of knocking on a violin, wouldn't it be better to build a specially designed 'knocking-box'? Hitting a violin is, if not destructive, quite difficult, sometimes dangerous, and has a very limited sound. These were the first purely acoustical instruments I built for the Logos-group using woods of different resonance and texture. And because even these simple constructions require some knowledge and understanding of material-quality and acoustical principles. I was soon drwan into the principles of traditional instrumentmaking: luthery, woodwind and reed confection, metal working for percussion instruments, gong and cymbal casting, skin treatments for membranes and even organ building. From these beginnings I started experimenting with all sorts of alternative materials and construction techniques.

I built instruments with all kinds of nontraditional tunings (metallophones, xylophones, teponatzli, flutes, and simple clarinets) and I became fascinated by the instruments of Harry Partch, although it was a big disappointment when I heard his music, much later. But Russolo's instruments whose pictures and sketches I had long known still fascinated me even after hearing them.

I worked on several frictiondrums and other similar instruments (e.g. waldteufels) next to string instruments according to the principle of the Gopi-Yantra, using cans or brass membranes. Animal membranes seemed tto fragile and plastic tended to be far too elastic, so I looked into other acoustical realizations of sound effects and modulation possibilities. Reverberation was easily achieved by tightly fastening long thick spiral springs to the metal membranes of the instruments, or by welding many small steel-rods to the membrane, a principle used very beautifully by Harry Bertoia, and in a more basic way, by French Baschet Brothers.

Large springsteelplates can also be used, like the earlier singing saws and the flexatones. On the other hand, ringmodulation is possible using non homogeneous strings in elaborated networks, and for windinstruments, using anti-conical pipes with mutant cavities, or by placing two or more mouthpieces on a complex tube-system which joins into a single exponential horn. Bicorbassoons, subbassonets, multi-person horns, Vandemoortelofoons, springcans, wire-violins, canharps, clavichords, and experimental sanzas were created.

All of these found their use in the "Ghent Philharmonic", a workshop for creative music, founded by Logos in 1976, as a weekly evening when anyone interested in creative music could participate. This and other adult education initiatives stimulated a demand for workshops in alternative instrument-making. The first project of this kind which found its way to the public was "Ohre" (ears), which I still consider in its charming simplicity, one of our best achievements. It consists of nothing more than two long flexible large diameter plastic tubes with giant papier-mache ears fastened to one end of each. The public, mostly passers-by, was invited to listen in. The other end hid tiny sound objects which offered the solo-audience a "concert for one". In the midst of the ceaseless city pressures, an ear to ear intimacy, an island of attention and fragility, was created. Very rare were the listeners who didn't show a broad smile when they tried the "Ears"!


 This largest of all that I've designed so far, was designed to be a public happening, the "Pneumaphone-project". Very broadly considered one could consider it an organ. Though an organ works with a constant airpressure and with pipes with invariable pitch and timbre. In the pneumaphones pitch, timbre and volume are in a complex way dependent on the applied airpressure that varies in function to what the "players" do to the instrument.

The set up for this instrument requires at least 200 square meters. Four heavy specially constructed compressors steadily supply air to the instruments. This air is routed into 24 large inflatable seats in the shape of tetrahedrons. The public and the performers alike are invited to sit and play. Of course, the wind pressure in the seats keeps changing while the air is blown into the Pneumaphones where the actual sounds originate.

Each Pneumaphone has a different sound action/mechanism: single or double reeds, flutes, mirlitons, whirlflutes, sirens, membranes, etc, lend their diverse voices to Boreas, Kolpia, Zu, K, Ehecatl, Aeolus, Favonius, Apu-Hau, Awhio-Whio, Gucumatz, Tawhiri, Teshub, Eurus, Notus, Adad, Apu-Matangi, Oonawieh-Ungghi, Xix etc... Together they compose a single large wind orchestra, the Pneumaphone-project.

The sonorous result is the product of full integration of body-movement and tactile/sensual relations both with the instruments and other players.

Pneumaphone is more than just a big acoustical musical instrument: it constitutes a world of sound experience in itself. This project also tries to mean more than merely a music compositional concept: it is a thought experience, a genuine music philosophy in itself.

[Pneumaphones: Catalogue on the web...]


 After 'Pneumaphones', I returned to electronic design making use of lessons I learned from my earlier experiences. My new project was sort of the opposite of pneumaphones: they were big and acoustic but the new construction-piece became subminiature and electronic. Both are theatrical and visual in appearance. I named this new project 'HEX' because most of the code is in assembly language for a dominating central and small computer.

For the sound generation I used small, fast dedicated computers to strictly control the vibrational modes of the physical objects incorporated on the printed circuit boards of the individual instruments. They function so that periodic oscillations will never occur. The circuit strikes the object, then reads in any occurring resonances. A numeric calculation follows resulting in the outputting of a sequence of pulses slightly different then the number first read in. From here on the process (a recalculated feedback loop) repeats until a stop instruction follows. These circuits are individually controlled in turn by a small laptopcomputer serving as a central microcontroller which is connected to the individual cards with 8-bit wide parallel bidirectional links. Originally a modified Epson HX-20, (the very first laptop computer on the market), but in more recent versions, a modified Toshiba T1000, runs the programs for either the concert or the installation version of the piece. As most of the real-time algorithmic tasks of this setup take place on the level of the individual instruments-on-a-card, it is possible to use of a small central computer, its task limited to the execution and control of the macrostructure of the musical composition. In the concert version, this program is interactive letting me operate the central computer and often enabling me to manipulate the expressive course of the piece in real time. Since any time the computer spends on performing calculations is lost time for the audience, it makes extensive use of Eproms containing lookup tables for the piece. These chips are integral to the score, and turn the computer into a dedicated machine.

In the piece, the computer together with the operator take the role of the orchestra (in much the same way as the violin solo in a classical concerto). But, the violin does not get a completely individual musical line, since its sounds are computer accesible and can be modulated and integrated in the orchestral palette. In this respect the piece becomes really interactive. Since "Hex" in many respects is more an orchestra then a composition, as an apparatus it makes possible a vast variety of different 'concertos' all presented under the generic name "Hex". It's a bit like the Indonesian Gamelan.

The visual feature of all versions of "HEX" -all the circuits, instruments and boards left open and bare- make the functioning of the attached physical objects visible to those who watch them closely enough. On the one hand there's something quite magical in its general appearance but on the other, demystifying for whoever comes close to examine it.

Further reading: HEX-project


 In 1990-91, I made a jump into yet completely different technologies: arc welding, the most Zen-like technology I can think of. It was the construction of a concert hall seating 150 people for the Logos Foundation, in the shape of a tetrahedron. I was already fascinated with the tetrahedron as the simplest imaginable regular polygon in 1969 for the acoustical properties of the shape: tetrahedron-spaces do not have a resonant frequency and thus, in principle are linear to sound and music. So I had done many experiments with loudspeaker-enclosures in the shape of regular tetrahedrons back then. Although results were encouraging, this shape was so unpractical to move around or even to place in our conventional rectangular architecture, that the idea was pushed to the background. Years later when we got the chance to purchase an adjacent factory building, I took up the idea of tetrahedron shapes again, and started making designs and calculations towards the possibility of erecting a tetrahedron concert space. It took me about 8 months to erect the thing and securely weld the whole together. Within the year, the Logos Foundation opened its new experimental concert-hall and the acoustics are generally acclaimed as excellent. We now are able to offer audiences more than 100 new and experimental music concerts a year in close to ideal acoustical and infrastructural circumstances.

Further reading: Logos Tetrahedron Concert Hall

Last updated on July 25th -3 by Godfried-Willem Raes



  1. - "Bellenorgel" , IGLOO-records, IGL-004, 1979
  2. - "Composition/Improvisation", IGLOO-record IGL-011, 1982
  3. - "Pneumaphone", IGLOO-records, IGL-050, 1987  [Link to album texts]


- "Pneumaphone" (photographs B&W)

- "Holosound"-performance (color picture)

- "Beltelefoon" , a sound sculpture

Originally written 1989. Published 1993. Last updated: september 09th -2