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E PUR SI MUOVE...
2001 15:05 4
       
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The sound material used in E pur si muove… resulted from a series of experiments with Symbolic Sound's Kyma / Capybara 320 sound computation system. I tried to implement analogue patching techniques based on my experience with the Institute of Sonology's voltage controlled studio.

When I attended Jaap Vink's classes during the Sonology one-year course in 1981, one of the synthesis models he showed consisted of a feedback setup with ringmodulators, filters and delay lines.
A sinewave oscillator is connected to a ringmodulator. The output is fed through a compressor, a reverberator, a filter and a delay line (a tape recorder) into the second input of the ringmodulator. With some amplification in the feedback loop it is possible to gradually build up a complex sound which keeps changing its timbre slowly.

A more complex setup involves four oscillators, four ringmodulators and four delay lines, providing a wider range of sounds and quadraphonic output. This setup was now digitally implemented in Kyma and the results are used in E pur si muove….

Kyma patch example Kyma virtual control surface

In the final version of the patch, the following parameters are defined:

Osc. Levels: Output level of the 4 oscillators.
Osc. Freq's: Frequency of the 4 oscillators.
Second sine Freq: Frequency of a mixed-in second sinewave.
Second sine Level: Output level of the mixed-in second sinewave.
Noise Freq: Frequency of a filter that controls the band-pass of a mixed-in noise generator.
Noise Level: Output level of the mixed-in noise generator.
A250Hz, A500Hz, A1000Hz, A2000Hz, A4000Hz, A8000Hz, A16000Hz Output levels of a series of band-pass filters inside the feedback loop.
Mod Freq: Average frequency of a slow random frequency-modulation of the four main oscillators.
Modulation Depth: Depth of the slow random frequency-modulation of the four main oscillators.
Spreiding: Distance in frequency between the four main oscillators (a setting of 0 = equal frequency).
Porta: Transition time of the parameters to the settings of a new preset.
Delay: Delay time of the four delay lines in the feedback loop.

 

Another technique I wanted to implement in Kyma was 'tendency masking' as I used it in my composition Geoglyphs. However, instead of designing a complex series of different masks, I decided to base the mask shapes on slow triangle-shaped control signals as shown in the following picture:
 
tendency mask based on triangular shapes  

The staircase figure results of sampling values within the mask's range.

The model implemented in Kyma uses two of such masks: one to control the limits of 4 random sources for the frequency of 4 oscillators, and one for another set of 4 random sources to control the oscillators that modulate the frequencies of the first set. The mask's limits are visualised in the virtual control surface as red horizontal lines moving up and down. From left to right they represent: lower limit of the carrier frequencies, upper limit of the carrier frequencies, lower limit of the modulator frequencies, upper limit of the modulator frequencies.

 
Kyma virtual control surface  
Disk recordings of this patch were also used as a source for further sound transformations, which appear in the piece as it develops.

click to play excerpt 1 click to play excerpt 2 click to play excerpt 3