FIG. 1 is a perspective view of a speaker for a light bar incorporating our new design. FIG. 2 is a front elevation view of the speaker of FIG. 1. FIG. 3 is a top plan view of the speaker of FIG. 1. FIG. 4 is a right side elevation view of the speaker of FIG. 1. FIG. 5 is a left side elevation view of the speaker of FIG. 1. FIG. 6 is a bottom plan view of the speaker of FIG. 1; and, FIG. 7 is a rear elevation view of the speaker of FIG. 1.