Abstract: A musical instrument such as a guitar including a structure such as a guitar body and a vibratory element such as one or more guitar strings mounted to the structure is provided with a pickup for detecting vibrating motion of the vibratory element and providing a pickup signal representing such vibration and having a predetermined phase relationship thereto. A driver is provided for applying a drive force to the vibratory element or string so that the drive force has a predetermined phase element relationship to a drive signal. A feedback circuit accepts the pickup signal and provides a drive signal to the driver in such fashion that the drive force supplied by the driver is substantially in phase with the vibration. Thus, the feedback circuit may be arranged to accept the pickup signal and convert the pickup signal to the drive signal so that, for at least some frequencies of the pickup signal, the drive signal differs in phase from the pickup signal.

Abstract: A sustainer for providing sustained sounds from a musical instrument has a feedback circuit for converting a pickup signal representing a vibration of a string or other vibratory element to a drive signal and applying drive forces to the vibratory element responsive to the drive signal. The sustainer is arranged to compensate for the phase lag of the pickup signal relative to motion of the vibratory element and to compensate for the phase lag of the drive forces provided by the driver relative to the drive signal. The feedback circuit may be arranged to provide a phase difference between the drive signal and the pickup signal such that the phase difference varies with frequency towards a drive signal leading phase difference with increasing frequency. This phase compensation provides enhanced response of the strings in the fundamental mode of vibration. The driver preferably is arranged so that the drive forces applied to the strings do not vary with lateral movement of the strings.

Abstract: A sustainer for providing sustained sounds from a musical instrument has a feedback circuit for converting a pickup signal representing a vibration of a string or other vibratory element to a drive signal and applying drive forces to the vibratory element responsive to the drive signal. The sustainer is arranged to compensate for the phase lag of the pickup signal relative to motion of the vibratory element and to compensate for the phase lag of the drive forces provided by the driver relative to the drive signal. The feedback circuit may be arranged to provide a phase difference between the drive signal and the pickup signal such that the phase difference varies with frequency towards a drive signal leading phase difference with increasing frequency. This phase compensation provides enhanced response of the strings in the fundamental mode of vibration. The driver preferably is arranged so that the drive forces applied to the strings do not vary with lateral movement of the strings.