Last chance to see United Visual Artist's Chorus installation at the Howard Assembly Room in Leeds, which runs until the end of this month. These photographs of the piece, lovely as they are, don't really convey the full immersive nature of the work. Commissioned by Opera North, Chorus is essentially an audio/visual installation featuring a series of mesmerising pendulum lights that each generate separate, but related, musical notes (created by Mira Calix) as they swing in and out of phase. Check out the video of the installation on UVA's site and click through for some more technical info on the project (and a reference to the influence of composer Steve Reich)...

"Chorus directly references the mathematical nature of music, particularly how it applies to rhythm," explain UVA. "Each of the pendulums functions as a metronome and the rhythms generated by each independently drive separate, but related, sequences of musical notes. The rhythms slip in and out of phase as the pendulums swing, and the tempo alters based on each pendulum's period. One of the early inspirations for this project was Steve Reich’s It's Gonna Rain from 1965 [see footage below]....

"On a technical side, the pendulums are not physically linked, but they are controlled together in a closed-loop feedback system. Momentum is added by powerful motors mounted at the pivot points; with the pendulum arms swinging freely when the motors are not running. Accurate feedback to the control software is provided by optical encoders mounted on each pendulum, and a central computer system applies power based on the speed and angle of each pendulum."

"Additionally, the effective length of the pendulum can be varied - the "bob" [containing the white led ring and speaker] can be shifted up and down by up to five meters, theoretically allowing alteration of the pendulums period of oscillation. The pendulums do not conform to the classic equation for SHM, the arm has considerable mass, so the shift in centre-of-gravity is less than the apparent change in length, and the friction is considerable. However, the shifting of the bob, combined with the motor control system allows enough control to deliberately shift the phase of the pendulums, for example to synchronise them or put them 180 degrees out of phase."

Steve Reich's It's Gonna Rain is discussed in this great South Bank Show special
at 2.25 mins in

Chorus by United Visual Artists.
Lead designers: Alexandros Tsolakis and Dave Ferner
Additional programming: George Konstantinou, Tom Whittock and Greg Bakker
Creative direction: Matt Clark