Nonlinearities and self-organization in the sound production of the Rhodes piano

Abstract

Over the last five decades the Rhodes piano became a common keyboard instrument. It is played in such diverse musical genres as Jazz, Funk, Fusion, or Pop. The sound processing of the Rhodes has not been studied in detail beforeIts sound is produced by a mechanical driven tuning fork like system causing a change in the magnetic flux of an electromagnetic pick up system. The mechanical part of the tone production consists of a small diameter tine made of stiff spring steel, the tine, and a tone bar made of brass, which is strongly coupled to the former and acts as a resonator. The system is an example for strong generator-resonator coupling. The tine acts as a generator forcing the tonebar to vibrate with its fundamental frequency. Despite of extremely different and much lower eigenfrequencies the tonebar is enslaved by the tine. The tine is of lower spatial dimension and less damped and acts nearly linear. The geometry of the tonebar is much more complex and therefore of higher dimension and damped stronger. The vibration of these two parts are perfectly in-phase or anti-phase pointing to a quasi-synchronization behavior. Moreover, the tonebar is responsible for the timbre of the initial transient. It adds the glockenspiel sound to the transient and extends the sustain. The sound production is discussed as synergetic, self-organizing system, leading to a very precise harmonic overtone structure and characteristic initial transients enhancing the variety of musical performance.