Modifying the Resonances of a Xylophone Bar Using Active Control

As imple active control method is described which extends the possibilities of ax ylophone bar.I ta llows the performer to modify the vibration of its structure, unlikepost-processing effects involving loudspeakers. These variations change the characteristics of the partials radiated by the bar.T he xylophone bar,m ade of composite material, is equipped with twoactuators and one sensor in PVDF (polyvinylidene fluoride), the mass and stiffness of which do not modify the mechanical characteristics. Ac ontroller in af eedback loop is executed on am idrange digital signal processor.I ti sc omposed of as um of second order band-pass filters. The selection of the controller coefficients relies on the measured transfer function between the input of the controller and the output of the sensor.F irst the active control method is designed to modify the resonance peaks of as imple model of ax ylophone bar,w hose transfer function is as uperposition of three eigenmodes. Then it is applied to the real system. It is illustrated by increasing and reducing the amplitudes and/or frequencies of the first resonances, and by modifying the tuning of the xylophone bar.