Threaded Rods
Threaded rods inserted (perpendicularly) through holes drilled in the gum and held tightly in place (clamped) with nuts form a simple but robust setting that is not at all simple in its sound. The threaded rod allows us to easily adjust vibrating lengths of clamped rods and fix them somewhat permanently once adjusted. It was one of the Baschets’ favourite materials to use because of its commercial availability and because of its suitability for mounting modular structures that can be easily modified.51 Throughout the history of Baschet sound sculptures we find threaded rod: in their first experiments, in small DIY kits, the big museum pieces, in participative sound sculptures, automated sound fountains, sound windmills, etc. (even in the well-known Cristal).
When comparing smooth rods to threaded rods, we find that the cut threads have little effect on the vibrational mode of the rod; the overall weight of the rod is negligibly reduced, but nothing else, according to our study of the resultant sound, is affected. Since we have addressed the use of threaded rods with weights in other chapters, here we aim to go deeper into the complex behaviour of compound rod systems with the examples of an original Baschet sound sculpture, the Kawakamiphone, and an après-Baschet piece, Zeikani Circulophone, that features intentional tuning on one side of the gum and found tuning on the other side The observations we have made regarding the timbral and xentonal aspects of these sound sculptures may help to give a foundational understanding of clamped threaded rod systems in general.
Kawakamiphone, 1970
Oscillators: eighteen thick threaded rods, 18mm in diameter, clamped to a thick gum (three steel plates stacked together). The gum is suspended with ropes from an external pipe frame in perfect and secure equilibrium for very efficient acoustic isolation.
Activation: percussion (bowing is also possible).
Radiation: nine large, thick cardboard cones (with wooden cores) connected to the gum with square metal bars.
Gamut: each rod has a different length, creating a found xentonal system.
Resonators: heavy spring coils connected to the gum add reverb to the system, and piano wire whiskers connected to some of the rods increase the presence of higher overtones.
Let’s look closer at some aspects of the sound and structural design of Kawakamiphone: these huge cones have a pretty wide frequency response but do not reach the very low end that other larger speakers can. We believe it is a conscious choice by master François, since he used other larger speakers (two square meters and larger) on other sculptures in the same Osaka 1970 exhibition. Kawakamiphone features this array of nine cardboard speaker cones that produces a warm and clear sound, never overdriving even when the oscillating system is activated to its maximum.
We have already explained how this kind of oscillating system works as a whole: each element (rods, radiators, or gum) responds to the complex spectral sounds created by one of the rods with its own resonant overtone frequencies. Let’s now look more closely at these distributions of elements. The rods in the Kawakamiphone are all the same length, but new vibrating lengths are imposed by the position in which they are bolted to the gum, with sections of rod extending on either side. Each rod is divided into two segments, each vibrating independently, but again sharing its possible resonances with the rest of the oscillating system. The lengths of each segment have been defined according to an arbitrary visual concept, following an imaginary (visual) diagonal that does not attend to any (aural) intonation system. The resultant gamut of sounds was not intended to articulate a precise sequence of pitches but was more of a controlled experiment to explore the sonic result of a visual arrangement of the oscillators.
As we can hear in the sound files, and see in the spectral view, the timbral behaviours of the rods on each side of the gum are quite different. We perceive a more cohesive timbre in the rods of the upper side, since they are proportionally closer in length; the clustery sound changes gradually rod by rod, with no major timbral contrasts amongst them. In contrast, the rods on the bottom side of the gum have proportionally greater length differences, creating a more diverse range of timbres.
On the upper side of the gum the rods appear as the longer set of lengths, following an arbitrary visual diagonal. Each of those long rods produce about six or seven overtones that blend in our ear like a bell or a ring-modulated electronic sound. The sounds are low in pitch, full, and dark.
The progression descends in pitch with no major timbral difference from one step to the other. It is also remarkable that some pairs of these rods are similar enough in length that they can resonate with each other, offering an even more blurred perception of tone clusters. In any case, these gradual differences in lengths create perceptible pitch differences at each step, but feature similar timbral qualities. Additionally, some of the rods excite the "whiskers" attached along the rod’s length, and some overtones are reinforced with some clarity as higher voices stand out, adding another nuance of variability in timbre.
The underside of the gum, with the shorter segments of rods following the same diagonal disposition, offers several different sound qualities, since the length differences are significant enough to cause a jump from one vibrational mode to another in several segments: their proportional lengths increase dramatically at each rod. The shorter rods with dramatically decreasing lengths offer fewer subsets of timbral colors, with highly unpredictable tonal consequences: sometimes our ear recognizes one or two pitches from each rod, sometimes a shorter rod has a lower tone than the longer neighbouring one. If we start listening at the longest rod, the next (shorter) rod is higher in pitch, similar to a tonal scale. As we continue, the rods become shorter, and the prevalence of lower overtones increases, reaching the “window of hearing” (as Bart Hopkin would say), so that when we arrive at the sixth rod the lower overtone has become audible and is lower in pitch than the much longer rod we started with. This progression continues, with the shortest rods offering new, different timbres, created by a new series of lower overtones rising into the hearing range.
The complexity here also depends on our hearing system: since the overtones do not follow the harmonic series, sometimes our ear picks up one or two of those frequencies: sometimes we hear a chord, sometimes we just hear one of the pitches, often depending on what we have heard previously. As we play a sequence progressing along the shorter rods, we are surprised with every new set of inharmonically-related frequencies that create different xentonal clusters and different timbral textures, impossible to predict soley by the length of the rods. Nonetheless, our ear can find joy and excitement precisely because of this odd and surprising behaviour, looking for contrasts and appreciating possible consonances and dissonances while still recognizing an overall resonating system that unifies those subsets of sounds.
This is the challenge and the game that the Baschet offers us to play, inviting us to appreciate these unique configurations: the structure has a unbroken visual line comprised of the linear increase in the lengths of the rods, but the sound surprises us with breaks in the continuity of the sound, in both tonal and timbral aspects. Here, there is no chance to play any previously known music but, rather, a great opportunity to enjoy these new sounds and the relationships amongst them, combining clusters and thick mid-range pitches, leading up to the shortest rod, which sounds like an hyperborean frozen icicle, all combined with a supernatural reverberation of the structure as a whole.
Since we can play on both sides of the gum, each rod has two different sound qualities, one on each segment, making it easy to compare and find pleasing combinations that inspire further exploration.
Kawakamiphone was created by by François Baschet and Alain Villeminot, along with a dozen assistants (Masatoshi Kawakami amongst them), in Japan for the Osaka Universal Exhibition 1970. The sounds and the images we have presented are from the restoration of the sound sculpture we completed in 2013 with the help of Villeminot and Kawakami themselves.
As a proof that this mounting system also allows for intentional tuning, we present this next après-Baschet piece.
Zeikani Circulophone, après-Baschet, by Roseta MB and Martí Ruiz, 2012
Oscillators: steel rods, 12mm in diameter, clamped to a heavy steel gum, resting on rubber to insulate it from the pipe stand. The gum itself has extensions welded to it for the radiators to bolt into and a pole as a spine though the center of the pipe to lower the center of gravity of the whole oscillating system (to make it more stable and reduce any danger of tipping).
Activation: percussion with wooden mallets covered in strips of bicycle inner tube.
Radiation: three stainless steel sheets, bent into curved shapes, attached at their base with bolts, adding a lot of resonance and reverberation to the sound.
Gamut: this is a nice example of tuned simple clamped rods. We decided to use a scale that could sound close to traditional Romanian scales to ease the explorations of the local participants (since this piece was built in Romania). It is an altered diatonic scale (C major with a G# ). It also allowed us to play a mazurka composed by the Lasry-Baschet orchestra. Anyway, there is a degree of dissonance that appears in the inharmonic overtones when the rods are aggressively activated with hard, wooden strikers (we added weight to three of the rods to correct some of those prominent overtones). In the video you can hear the upper side of the gum (which is usually out of reach for visitors). We decided not to trim the excess and kept the spare lengths to add even more resonance to the system. While setting the gum, we took the opportunity to record the sounds of those shorter rods with no tuning at all, just the random sounds appearing on the uncut spare lengths as a consequence of tuning the intended playable side of the gum. The shorter rods feature different timbral qualities, clearly contrasting, not only when compared to the longer tuned rods on the other side, but even in contrast within themselves, since the length differences in that upper section are different enough to behave in different vibrational modes, from the fundamental to second and third partials presenting themselves more prominently while the fundamental mode remains too quiet to be heard. Those unintentional sounds appeared far more interesting to us than the ones we had configured to be played by the audience, offering us their own natural possibilities (still quite unpredictable for us at that time). We wanted to underline the unexpected resonance that occurs amongst some rods on the upper side and the steel radiators. In some cases, the entire color of the sound is even more distinctive, roaring with a singularly energetic envelope.
This après-Baschet percussion was made in Romania, using recycled materials for the gum and column and was one of our first outdoor site-specific experiences as the new Baschet workshop team: Martí Ruiz in collaboration with Dr.Jep Cerdà, Vicmangles, and Roseta MB.
Those experiences taught us about the unpredictable interactions between all of the elements in these complex systems. Of course, after years of working with them, we must say there are opportunities to seek these kinds of sounds and dynamic timbral responses: tuning the resonant frequencies of metal speakers by working their geometry and tension. This is yet another field of research that requires either extensive empirical trial-and-error observation or extremely complex virtual modelling able to simulate the acoustical dynamic output of such geometries and material vibrational capacities. We don't know if this depth of modelling is possible to obtain, so we continue to learn and improve our understanding with the empirical method.
Figure 45. Kawakamiphone in Osaka Universal Expo’70, François Baschet’s personal archive. Unknown photographer. (Ruiz 2015).
Figures 49 and 50. Video and spectrogram of Zeikani Circulophone in Zeikani, Romania in 2012. Source: https://www.youtube.com/watch?v=4jZgIq5WOW4&feature=emb_logo
Figure 48. Marti Ruids and Sachiko Nagata playing Kawakamiphone in a concert at the Kyoto City University of Arts, following the restoration we completed in 2013. The complete concert is available for free here. Source: https://www.youtube.com/watch?v=xMQI42hLc7c