“The Feed-Drum is an imperial bass drum with a system of electronic conditioning of the skin conceived by composer Michelangelo Lupone and produced at CRM - Centro Ricerche Musicali, Rome. Through the principle of feed-back, the signal produced by the excitation of the skin was returned to the skin itself in the form of acoustic pressure. The result was the infinite prolongation of the sound. The system controls the damping of the movement of the skin, and therefore the decay rate of the sound, and permits isolation of high frequency modes by the combined action of nodes present on the skin and the amount of feed-back input energy.
The design on the skin surface is a simplified map of the oscillatory modes based on the Bessels functions. The map was limited to 13 diameters and 8 nodal circles, the latter divided into even semicircles (to the left) and odd semicircles (to the right).”