Creative Sbs A500 5.1 Speaker Driver →

The 5.25-inch 8-ohm subwoofer driver is easier to replace. Measure the cutout diameter (typically 118mm to 120mm). Look for a "full-range subwoofer driver" (not a mid-bass). A "Goldwood GW-205/8" is a popular mod for the A500, though you will need to drill new mounting holes.