Threaded Rods with Weights On Their Free Ends
Usually set in short segments of threaded rods, the weight formed by washers held in place by nuts lowers the tone of a clamped rod and radically changes the timbral qualities, producing a rounder warm sound. This mounting system still produces a tonal sound, not particularly clean but suitable for simple melodies, musical phrases and motifs with rhythmic roles. The Baschets referred to these short rods with weights as mushrooms. During setting, moving the washer less than a millimeter can alter the pitch by as much as a whole step, so it can be used to retune a short rod over a wide pitch range. To aid in achieving the desired pitch, the weight can be adjusted by adding or removing washers or using different washers of different sizes.
There are so many variables when permuting these simple elements that the range of timbres can be incredibly wide (our Circulòfon in the Multitimbral Settings section offers a good example of this breadth). The sound of mushrooms (short rods with weights) is easily distinguishable from longer rods without weights. If the sounds were to be presented acousmatically, most people would not identify the sound as a coming from a metal rod. When activated with soft mallets, the timbral qualities of these short rods tend to be more obscure, with less overtones than the same rods without weights.
Let’s look at a classic application of this Baschet mounting system on an original Baschet piece:
Zagreb, circa 1980
Oscillators: 8 short threaded rods, 6mm in diameter, with weights (washers) on their ends bolted to an iron gum, suspended by thin rope. Also: three pairs of aluminium plates forming crosses, each pair suspended by rubber pipes so as not to interfere with the system of rods.
Radiation: the mushroom rod system is radiated by two thick cardboard cones. Each pair of plate crosses is radiated with a smaller cardboard cone.
Gamut: the mushroom rod system has a mid-range, full, wet, thick sound. The sound offers a relatively clear tonal progression, creating nearly a tonal scale: F#, G#, A#, B (slightly sharp), C#,D#, F.
In this audio file – recorded in a dry (less reverberant) space – we can hear, and see in the spectrogram, the short, solid attack and the combination of every rod’s frequencies being activated, the rod system working as a whole, and how only some frequencies remain prominent enough to offer a clear pitch perception. There are also some low frequencies, probably part of the gum and cones’ natural frequencies, that add consistency to the overall sonority.
This systemic behaviour makes it challenging to distinguish how many overtones a single mushroom rod can produce, but the spectrum data shows that the frequencies appearing on each rod hit are the fundamentals of the other rods being activated by the percussive strike on each rod, so there are no other overtones ringing at length after the attack. This is one explanation of the lack of brightness in these sounds, while pitch information is still conveyed through a warm, round, opaque timbre.
Some of our après-Baschet experiments show that longer rods with weights on the free end also feature vibrational patterns that allow for more consonant ratios such as perfect fifths. We can observe this phenomenon in our Axolotl Multitimbral Percussion, presented in the Multitimbral Settings within the examples section.
Figure 51. Video of Zagreb. Source: https://www.youtube.com/watch?v=W4R_1v9cg1I