Simone De Haan/Greg Schiemer: Improvisation (1983)

Abstract

"In 1976 Greg Schiemer began designing and building some simple electronic circuits which he mounted in plastic kitchenware and called the Tupperware Gamelan. Having played both in a real gamelan and in a r ve improvisation group with AZ music, his initial objective was to form an ensemble of musicians playing small unsophisticated electronic musical instruments. In 1983 Kai Tai Chan, director of the One Extra Company, proposed a work using instruments of the Tupperware Gamelan, as part of a stage set for a dance performance. TheresultingworkwasPorcelainDialogue. TheGamelan by this time included sixteen analog oscillators and a digital control unit. Instead of being a collection of instruments played by a large number of people, each of these instruments, called UFOs, was modified to allow it to be used as a pendulum, functioning as part of a stage set and operated by a single performer. Each oscillator was mounted in a small Tupperware container which contained a tiny amplifier and loudspeaker. These were suspended from the ceiling of the theatre by the cable~ that connected them to the digital logic box. In performance, these containers were swung back and forth, further dispersing the sound. The pitches, timbres and rhythms the oscillators played were determined by the digital control unit. This control unit, constructed in a much larger piece of Tupperware, had a number of switches on its cover. In performance, these were operated by one of the dancers, who followed a score of symbols such as '3 :30, C3 down' , meaning tum switch C3 down at 3 minutes and 30 seconds into the piece. The heart of the digital control unit was an 8-bit pseudo-random sequence generator. This provided two separate binary signals for each of four binary-to-decimal decoders, each of which drove the lines going to one of sixteen oscillators. Any group of four lines could be made to switch on or off depending on the two binary signals controlling the decoder, the resultant melodic movement at times beating in unison with another oscillator, at times 'jumping' from one oscillator to another, at times proceeding like a conventional hocket. These binary lines had additional switches which allowed Boolean transposition of the code. For example, a sequence of code such as 1, 3, 2, 4 could be transposed to 2, 1, 3, 4 by altering one binary switch. This meant that the spatial path followed by the melodic line could be affected by the four possible combinations of two switches. The logic signals which drove the control lines could also be modulated with audio signals, forcing side-bands from each of the local oscillators. In this way, each of the sixteen oscillators was capable not only of producing four pitches unmodulated, but was able to produce a va~t variety of timbres, usmg methods of modulation with properties similar to both pulse-width modulation and amplitude modulation. The instrnments heard in this recording are the ones used for Porcelain Dialogue. They were set up to swing from the ceiling of the Lewellyn Hall in Canberra, and then played by the composer in this improvisation with rombonist Simone de Haan. This recording of the Tupperware Gamelan though realising something less than the full potential of the instruments, is the only one available." -- Greg Schiemer