Vertical Pendulyre with Prague Bubbles
Graphic Score (2007)
by Dan Senn

In the graphic score below, each block of pulses (the first example, in the upper left-hand corner, has 3 of these) represents about 20 seconds of time. For the Hillsboro installation, the sections are sampled randomly along with a set of bubbly interludes. The blue areas indicate subaudio tones as defined in the red area above. The black lines refer to the loudness of the waveform. Here and there, a lighter line is visible indicating a pan from 1 channel to another (this is clear in examples 13-16). The upper half of each graphic refers to the corresponding upper/lower pendulum line of the instrument.

Click to graphics enlarge and listen to a section......

The score for this installation is made of subaudible sine wave pulses and audible waveforms (bathtub bubbles recorded in Prague in 2006).

Following is a general description of how my pendulum instruments work, and then the process I use to compose for them.

The mallets for these instruments are made from thin pine dowels (pendulums) and are set in motion using subsonic freqencies stored on a CD, computer or mp3 player, and transferred to the pendulums using the following sequence of connections:

• a storage device is connected to an amplifier which
• is connected to a modified speaker (usually a 3-4" woofer) with a metal loop embedded at the center which
• is attached a nylon line which
• is connected at about 90 degrees to a pendulum line, also nylon, with metal springs attached at either ends
• upon which pine dowels (mallets, aka pendulum beaters) are attached at or near their balance points. These rock to and fro while beating the surface of the floor, wall, piano wire, nylon line, resonant object or combinations of these.
• These beatings are left to sound acoustically or with amplification using piezos transducers.

Compositions for installations, recordings or concert performances involves:

• positioning and balancing the pendulum beaters along the pendulum lines (plines) for density and textural characteristics,
• testing the pendulums and plines and positions for their resonant characteristic using subaudio sine waves in the 0-19hz range,
• creating a library of these subaudio waveforms along with performance notes,
• creating a library of audio sounds to be mixed the subaudio sounds, and
• organizing a composition, sometimes through-composed, which is often reorganized after the fact using simple algorithmic principles.

Compositions are created using a multitrack editor. I use Mark of the Unicorn's AudioDesk. The piece above is a representation of a work for the Vertical Pendulyre and Bubbles created for the Glenn and Viola Walters Cultural Arts Center in Hillsboro, Oregon in August of 2007.

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