In the context of more general considerations concerning the use of sound synthesis in contemporary music composition, the latest version of the physical modelling synthesis system Modalys is presented. In Modalys, the successor of Mosaïc, synthesis is based on the modal representation of vibrating objects. Modalys has been extended to allow modifications of the modal representation before and during the synthesis process. This extension is discussed in the light of the musical motivations of using sound synthesis in general and physical modelling in particular. The general trend towards a convergence of signal and physical models is discussed, and future extensions of Modalys following this tendency are presented.