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Listening to the rods above the gum in sequence, we can hear how the lower overtones gradually appear in the hearing range as we move from long to short rods, so that shorter rods are heard as having a lower pitch. Despite being physically shorter, a lower order of overtones enters our hearing range. For longer rods, the lower order of overtones are too low to be heard.

Round Rods

Smooth round rods can be found in various sizes of sound devices, from tiny DIY kits to massive sound sculptures. The following examples illustrate a variety of timbral and tuning aspects. We will look at five historic Baschet pieces that use clamped round iron rods: SAD, Brontosaur, Ticklephone, Amiens, Katsuharaphone, and an untitled tabletop mobile sound sculpture. 

The behaviour of round rods is paradigmatic of clamped elements, as presented in the Vibrational Modes of Clamped Oscillators section of this paper. What is interesting about this specific oscillator is the variety of possible mountings and the fact that smooth rods can be used as percussion elements but can also be bowed with string bows or wood strips impregnated with rosin. This is something we can also see in the Waterphone by Richard Waters.

We can find four mounting systems used to clamp round rods with the required rigidity: round rods clamped between two plates that create a “sandwich” gum, round rods with a curled end bolted to a gum, round rods threaded on one end and through-bolted to a gum, and round rods inserted into pre-drilled gums, secured by welding or press fit.

Round rods clamped between two plates that create a sandwich gum

SAD, 1967 (created for the Salon des Arts Decoratives of Paris) 

Oscillators: 15 round steel rods, each 3m long, clamped in a sandwich gum connected to a massive secondary triangle gum to add more mass. The longer lengths of the rods above the gum have felt rings at their tips to minimize the sound of the rods hitting each other. 

Activation: percussion

Radiators: three stainless steel cones

Gamut: the rods are placed with their ends forming an imaginary diagonal line, with an arbitrary progression of lengths creating a xentonal tuning. Each side of the gum (top and bottom) features slightly different timbral colors.

Listening to the rods on the bottom side of the gum, we find that the lengths are still close enough to feature a cohesive timbre and a similar overtone profile.







Brontosaur (aka Monumento a la Percussión), 196350

Oscillators: 28 steel rods, each 2 meters long, clamped in a sandwich gum.

Activation: percussion and bowing

Radiators: two massive aluminium cones

Gamut: the rods are set in the gum to form a diagonal with an arbitrary length progression, creating a xentonal tuning. Each side of the gum features slightly different timbral colors. The bottom side offers more contrast in the lengths of rods and therefore greater contrast of timbral range. 

Listening to the upper side of the gum with longer length rods, we find different spectral patterns, since the lengths decrease quite drastically. We can hear shorter rods in the same pitch range as the longer ones but with different timbres. The last rod, the shortest, has the lowest root tone of them all.

Listening to the bottom side of the gum, featuring much shorter rods than the other side, we can distinguish a different set of sounds: also clustery, but revealing more compact midrange sounds, creating a different reaction in the same radiators (probably through resonance with them). The sound is overdriven with a natural distortion that reminds us of electrified sound.  Again, in the fourth rod, shorter than the preceding three, a lower root tone appears, beginning a new series of rising lower tones, while the overall sequence of higher overtones loses amplitude and presence with each shorter rod.  


Round rods inserted into pre-drilled gums, secured by welding or press fit.

Cage on a Spring with Two Leaves, circa 1990

Oscillators: several round steel rods, 3mm in diameter, different lengths, press fit into holes drilled in a round stainless steel gum. The oscillating system is bolted on top of a hard spring, which is bolted to a heavy metal base for stability and security. 

Activation: the rocking of the oscillating system on top of the spring creates a random series of strikes as the glass ball rolls around inside the rod cage, creating a sharp activation of the rods, stimulating a bright sound above the fundamental frequencies of the rods. 

Radiation: Two bent stainless steel sheets add a bright resonance to the vibrations generated by the oscillating system. The speakers do not radiate the lowest band of frequencies generated by the rods, so the output is in the middle and high ranges of the spectrum.

Gamut: found xentonal tuning, different lengths displayed in a random sequence. 


This example is representative of many mobile sound sculptures made by the Baschets, particularly by François, in which there is an element of randomness in its activation. In most cases these are small or medium sized pieces, using a spring-mounted base or other means to add a touch of unpredictability. The pieces were meant to be easily activated with a push to start a rocking movement, so the ball rolls around inside the cage formed by the rods, striking them. The rods were not tuned to any particular music scale, since the intention was to offer random pitches. This piece, and others like it, invite the user to let go of control and appreciate sonic events as they occur, somewhat unpredictably but dependent on user input: the direction and amplitude of rocking. 

This particular piece, part of François’ own home collection, has no name and was probably made during the 1990’s. There are dozens of unique pieces, similar to this one, in the hands of private collectors around the world.

Listening to the shorter rods on the underside of the gum, we can hear greater timbral differences produced by greater length differences of the rods.

Listening to the demo of Brontosaur, we can observe the disparate timbral qualities of the radically different rod lengths. The rods on the upper side of the gum feature a more cohesive timbre, while the underside’s shorter rods feature more differentiated timbres (similar to Kawakamiphone in the clamped Threaded Rods examples). The video also shows different activations, dragging piano wire to create cascading bright sounds, rubbing with superball mallets on the radiators, and bowing the rods with cello bows.

Bowing the rods creates stationary waves that divide themselves into the harmonic series. The pitch of that stationary wave is one of the natural overtones of the rod, but once that wavelength is stimulated, the wave creates a new subset of harmonic overtones that are not part of the natural overtones of the rod. This counterintuitive behaviour, observed in many sculptures, is promising for future research. 

In the video above of Brontosaur we hear two rods being bowed along with Martí Ruiz’s voice. The musical result was artistically desired, but we understand it is confusing to differentiate the voice from the rods, precisely because they are all compound sounds in a harmonic spectrum. To aid the reader’s understanding, we have included the sound of a bowed rod on its own below.

In the spectrogram above we can clearly see the harmonic series generated by bowing one of the rods: the rod is forced to oscillate differently to its natural inharmonic vibrating mode.



Ticklephone DIY kit, circa 1980

Oscillator: 14 round steel rods, 5mm in diameter, each half a meter long. 

Activation: percussion

Radiator: two cardboard cones

Gamut: found xentonal tuning, each side of the gum features asymmetrical lengths. One side features more differences in length, therefore some timbres are also particularly different.





In this mid-size setting we can appreciate the colour emerging from this scale of elements, a fuller, warmer sound than the previous examples. We also appreciate the found tuning: clustery tones with a clear intention for a coherent timbral range design. Shorter rods ring out in their fundamental mode, whereas longer rods vibrate in higher vibrational modes: their overtone ratios differ and therefore produce different timbral colors, some of them more like bells, some of them more like water drops, and other timbres we won’t attempt to describe. The proximity of the rods to one another allows for sweeping strikes that activate all the rods in one quick gesture that creates interesting cascading sounds.


This is an original DIY kit, designed by François himself. The idea for the DIY kits is that everyone can mount (set) the rods in their own way. The gums provided in the kit have holes drilled in them to facilitate the clamping of threaded rods with nuts, but the kit also allows an alternate mounting method: a sandwich gum created by clamping the rods between the two gums.


Round rods with a curled end bolted to a gum

Amiens, 1963 

Oscillators: 30 round steel rods of different lengths, curled at their ends and bolted to a round gum. 

Activation: percussion

Radiation: 3 large aluminium cones

Gamut: random pitches created by 30 different lengths placed randomly along the gum, creating a random sequence when played consecutively.




































There are at least four different kinds of timbral qualities to be found in Amiens, low and dark, from deeper to shallower, brighter or more opaque, and middle wet bells, some more clustery, some more monodic. These sounds are quite unpredictable and fun to explore. 

We have found pictures of Amiens with different rod arrangements to fit the space and the ceilings of different venues in which it was exhibited, so it appears that the Baschets did not define a specific configuration of the rods. It is an invitation and a challenge for the builders and players to find the combinations of sounds that please them the most.











Round rods threaded on one end bolted through to a gum

Katsuraphone, 1970

Oscillators: 19 round rods, 6 millimeters in diameter, threaded on one end and bolted to a semicircular gum. The Katsuraphone also features a set of strings with a tremolo arm and suspended plates not discussed in this presentation.

Activation: percussion, bowing (the semicircular display also allows for bowing)

Radiators: 4 aluminum cones (the other cones radiate the sound of the string set)

Gamut: Each rod has different lengths and different complex sounds, creating a xentonal gamut, with some particular tone clusters that appear to be repeated with different timbral nuances.






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Figures 25 and 26. Ticklephone, pictures by Martí Ruiz. (Ruiz 2015).

Figure 28. Amiens. Picture by  Martí Ruiz, Barcelona, 2015.

Figure 19. Audio recording and spectrogram of the upper side rods of SAD. (Ruiz 2015).

Figure 20. Audio recording and spectrogram of the bottom side rods of SAD. (Ruiz 2015).

Figure 22. Audio recording and spectrogram of the bottom side rods of Brontosaur. (Ruiz 2015).

Figure 24. Audio recording and spectrogram of a bowed rod from Brontosaur. (Ruiz 2015).

Figure 27. Audio recording and spectrogram of Ticklephone. (Ruiz 2015).

Figure 31. Picture of restored Katsuharaphone, Kyoto City University of Arts, 2015, picture by Martí Ruiz. (Ruiz 2015).

Figure 18. Picture of SAD in Berlin 1972. Unknown photographer. (Ruiz 2015).

Figure 21. Brontosaur, in Berna 1965, picture by Hans Schnyder.

Figure 23. Video of a concert and workshop organized around the Baschet Brontosaur with our colleagues from UNAM. Baschet Soundsculpture Workshop at the Museo Universitario de Arte Contemporaneo in México City, 2014. Source: https://www.youtube.com/watch?v=rGNc5BkU_YI&t=2s

Figure 35. Audio recording and spectrogram of Cage on a Spring with Two Leaves.

Figure 29. Detail of Amiens. Unknown photographer. François Baschet personal archive. (Ruiz 2015).

Figure 30. Audio recording and spectrogram of Amiens. (Ruiz 2015).

Figure 33. Audio recording and spectrogram of the bottom side rods of Katsuraphone. (Ruiz 2015).

Figure 34. Cage on a Spring with Two Leaves,picture by Ana Sanchez Bonet.

Figure 32. Audio recording and spectrogram of the upper side rods of Katsuraphone. (Ruiz 2015).