Nichtlinear rückgekoppeltes Schwingungssystem



Klanginstallation, gezeigt auf der "Langen Nacht der Wissenschaften" 2003 in der mathematischen Fachbibliothek der TU Berlin.
Ein Gemeinschaftsprojekt von Volker Nikel und Thomas Seelig.
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The "resonating system with non-linear feedback" is the first attempt to use simple strategies to get complex output. In this case the vibrations of the steel sculpture are picked up by a transducer, processed with a relatively simple Max patch and then feed back into the system with a "body shaking" speaker, mounted on the side.
The non-linearity is achieved using amplification with signal controlled gain control – a compressor – plus filters with external frequency control. Every time if a certain frequency becomes dominant in the feedback structure, the filters are tuned in a way to suppress just this frequency, so that the system is forced into a new state. Additionally are LFOs build in to create slow drifting frequency changes. These LFO/filter structures are encapsulated in the blocks called "Process1" to "Process5". To get a little bit of low frequency parts two frequency dividers are also part of the circuit.
The image of Max patch below shows the structure.
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