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.