Check the weight of your speaker cabinet. The weight of different models of speaker cabinets varies greatly. For lighter speaker cabinets, a simple plastic furniture caster is all you need. For heavier speaker cabinets, a heavy-duty caster is necessary. When checking the weight of the speaker cabinet, consider any speakers you may stack on top of the cabinet as extra weight.
Choose your casters. Casters come in many shapes and models as well as many different prices. For a speaker cabinet, plate-mounted or corner-mounted casters are your best option. Swiveling casters make moving the speaker cabinet over cables easier, which is an important consideration for sound reinforcement applications. Look for casters that have a locking mechanisms and use at least two of them for you speaker cabinet so that you can keep it from rolling unintentionally.
Tip your speaker cabinet on its side. Make sure that the speaker is completely unplugged. Find a soft surface like a foam pad or a blanket to lay the speaker cabinet on so you do not damage the exterior. If it is a large speaker cabinet, find someone to help you lay it on its side. Even a small jolt can seriously damage the speakers inside the cabinet.
Attach the casters. It is best to attach the casters at the corners because you have the least chance of puncturing an important component with a screw. Use wood screws that are long enough to securely attach the casters. Be aware of any resonance ports and be sure not to puncture them as it can change the sound of the speaker cabinet. Also be sure that all screws are firmly attached to avoid rattling.
Try out the new casters. Set your speaker cabinet back up. Use caution when tilting it because the casters may cause it to roll unexpectedly. Move the speaker cabinet around to verify the casters are rolling properly. Try rolling the speaker cabinet over a few cables, and lock the casters to make sure the speaker cabinet stays secure. If the casters are not functioning to your liking, remove them or replace them.