luis jure wrote:

> in my orchestra pitch tends to raise when I gets close to 1, and for I >
> 1.2 aprox the system becomes unstable, as you can see in the second
> note. i'm not sure if that's something inherent to the technique, or
> maybe it's a problem with this particular implementation.

Most of the cool techniques available with feedback FM in the Yamaha FM
synthesizers are not truly based on frequency modulation, but rather on
Phase Modulation. Probably the best way of doing this in Csound is with
a phasor/tablei combination.