Autophagy II - [Mikrophobie].

For feedback-driven table-top electric guitars, feedback-driven tam, percussions and live electronics.

Download Score

Video excerpt

 

The integral track can be downloaded from the Soundcloud player at the bottom of this page

This piece is the second episode of a cycle of works on self-driven acoustic instruments and their performative possibilities. It has been written around two instruments whose sound production happens via acoustic means (the resonance of a very large plate in the Tam tam and the vibration of strings in two electric guitars), but which an electro-mechanic augmentation allow to produce sound under very special conditions. Compared to its previous chapter, it is an attempt to build on even more unstable ground.

In each instrument the sound is picked up and fed back to its body of origin via vibrations speakers. The phenomenon this simple coupling produces, generally known as feedback, allows to sustain these instruments's sound indefinitely, showing some of their specific sonic qualities and physical behaviour under a new light.

This augmentation not only radically transforms the instruments as such, but also the way it is possible to interact with them, rendering many of the known performing techniques unusable.

Every small change in their physical configuration influences its overall sonic response producing, in turn, infinite loops of small physical transformations. Feedback is a powerful yet wild sonic force and to keep it under control is a challenging activity.

Planning is difficult if not impossible and what is left with is to react and fight back to keep the sound from going into undesired territories. The performers are forced to be half scientists, half priests and half adventurers. Every section is a specific sonic situation, an artificial ecosystem with a reduced set of rules and behaviours, the performers try to discover, inhabit and navigate.

The score is thought as a map to explore this ever-changing sound-world. It provides strategies and hints to solve specific questions, and it’s closer to a chart than to a traditional music score. The piece is a ritualistic trip, but like in every trip, actual or metaphoric, the journey is never without surprises.

Audio recording

 

Maarten Stragier - tabletop electric guitars

Tom De Cock - percussions

 

Produced by Centre Henri Pousseur and Muziekcentrum De Bijloke.

With the support of Istituto italiano di cultura, Bruxelles.

Technical description

Autophagy II is the result of a year-long research on the augmentation of electric guitar and a 60” Symphonic Paste Tam trough vibration speakers of different size. The final version of the work uses one bass shaker, placed slightly off the centre on the back of the tam, and a smaller 30W tectonic element full range driver positioned on the inside of the upper part of the rim. Two similar driver are also placed on the guitar, in the places which resulted as the most resonant spots: right underneath the left side horn of a strat-like shaped electric guitar and underneath its head.

Each driver is fed with a dedicated power amplifier, and for the guitars their output is also controllable via a dedicated volume pedal for each guitar. The pedal positions during the piece is indicated in the score. The sound from the pick-ups is routed to a max/msp patch that analyses and modify it before feeding it back to the vibration speakers on the body of the instrument.

For the tam a similar system is put in place, using two custom built glove-microphones, that the player could use to control the feedback loop. On two elastic gloves a DPA 4061 is attached in such a way that the capsule membrane would stick out from the centre of each hand’s palm, facing outward. By simply moving the hand on the surface of the tape, different overtones of the spectrum of the tam are excited and kept in the feedback loop, while the shape of the hand around the microphone’s capsule also further sculpts the frequency response of the microphone, allowing for an intuitive exploratory performativity.

The function of the patch is to keep the signal of each feedback loop from going out of control, at the same time granting to the system, via a simple analysis module, a degree of adaptivity and reactivity.

The percussion setup was completed by two metal bars with contact mics, connected with a convolution and source filter model, coupling a a physical excitation with virtual resonance.

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