Studies on Feedback and Transmission

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In general, the system is composed of two different types of feedback processes. Firstly, complete (and generally static) loops that consist of a speaker or exciter coupled with an object (resonator/waveguide) which is then coupled to a microphone or piezo element whose output is connected to the input of the mixer where it can be manipulated before being fed back to the speaker/exciter 'input' of the object. By modulating the input gain, compression, EQ, and output gain settings on the mixer, it is possible to drastically alter the character of the resulting sound. Additionally, in some cases I decoupled the input and output elements into separate processes, thus creating input-only or output-only paths through the mixer that can be connected together in a dynamic fashion. In practice this could mean attaching a microphone or piezo element to an object and activating it with a 'free exciter' that can be moved freely, thus enabling various feedback paths through the object, and in turn, resonant behaviors. Such an exciter can also be used in conjunction with a static system to alter its behavior.

v1.0

Version 1.0 used seven objects as waveguides/resonators, all (except for the water bottle and the sandpaper sheet) were connected to both a speaker or exciter and a microphone or piezo pickup. (The sandpaper only functioned as a waveguide between the free transducer and the water bottle, which was only connected to a contact mic.) Each object created an independent feedback loop in one of two Behringer XENYX Q1204USB mixers. The performance was a sort of ‘live exploration’ of the sonic properties of the various objects, including:

• • water bottle [free transducer → AKG contact mic, mixer out also went to external speaker ch. 1]

  • 25 mm thick scrap piece of honeycombcardboard panel [exciter → contact mic, mixer out also went to external speaker ch. 2]

  • hollow styrofoam box [exciter → Rode condenser mic]

  • bent metal plate [exciter → piezo]

  • 25 mm x ~1.25 m pvc pipe [tiny speaker (that eventually exploded!) → Rode condenser mic]

  • glass window [exciter → Schertler DYN-V contact mic]

  • sandpaper from belt sander stretched between two tables [used in combination with water bottle & transducer]

v2.0

Version 2.0 was a more refined and 'deliberate' implementation of the project. Building off of the lessons learned from v1.0 I designed a more complex (and nuanced) system, and included new objects specifically designed to be better suited for the application. This time I used a Yamaha MG206C 20 channel mixer as the central control element and configured it as a sort of matrix mixer (using the AUX sends to allow me to feed the resonance from one object into another). By doing so, I was able to use a single object (the cardboard box) as a “primary” oscillator and dynamically combine its signal with the natural vibrational modes of the other objects; this technique enabled me to create a 'instrument' capable of producing more cohesive, non-kadenzklänge (specifically, Farbklänge, Texturklänge, and Fluktuationsklänge)* throughout the piece. A simplified schematic of the setup is shown in the figure below with details provided in the accompanying table.

* English: Non-cadence sounds (specifically color sounds, texture sounds, and fluctuation sounds). Lachenmann, H. 1996 [original 1966]. Theoretisch-Praktische Grundlagen, in Lachenmann and Häusler (eds.), Musik als existentielle Erfahrung: Schriften 1966-1995. Wiesbaden: Breitkopf & Härtel.

Play & Rec v01 - February, 2020: