The ornamental design for a musicalcontroller, as shown and described.
FIG. 1 is a top perspective view of the musical controller according to the present invention;
FIG. 2 is a top view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a first side view thereof;
FIG. 5 is a second side view thereof;
FIG. 6 is a rear view thereof; and,
FIG. 7 is a bottom view thereof.
The broken line portions of FIGS. 2, 6, and 7 showing unclaimed internal subject matter visible within design apertures form no part of the claimed design.