The ornamental design for a loudspeakercabinet, as shown and described.
FIG. 1 is a perspective view of a loudspeaker cabinet showing one side, front, and top of my new design;
FIG. 2 is a front plan view thereof;
FIG. 3 is a perspective view showing the front, top, and one side thereof; and,
FIG. 4 is a plan view showing the top thereof.
Shading lines shown in the drawings are intended to represent the approximate three-dimensional contour of the design, and are not intended to indicate surface decoration.