An outdoor speaker box is a great way to add music to exterior venues around your home---on the deck, in the yard, wherever you want music for entertaining. It's important when building an outdoor speaker box that you use speakers that are designed for outdoor use and that you place the speakers into a box that's sufficiently weatherproof. With some basic materials and tools, you can accomplish these objectives.
Cut two 8-by-8-inch pieces of marine plywood with your circular saw for the front and rear panels of the speaker box.
Cut two 6-by-8-inch pieces of marine plywood with your circular saw for the two side panels of the speaker box.
Cut two 5-by-8-inch pieces of marine plywood with your circular saw for the top and bottom panels of the speaker box.
Place the top, bottom and side panels together to form a hollow square. Overlap the side panels over the ends of the top and bottom panels so that the resulting box is 8-by-8-inches around the outside. Attach the pieces together with wood screws.
Caulk the inside seams of the box with silicone caulk.
Place the front panel onto the box and attach it with your wood screws. Caulk the seams on the inside where the back panel meets the box.
Place the back panel onto the box and attach it with your wood screws.
Cut an opening in the front panel of your box for the marine speaker, using a jigsaw. Reach inside the box and caulk the seams where the back panel joins the box walls.
Drill a hole in the back panel, directly opposite the opening in the front. Push the end of a length of speaker wire into the box through the hole from the outside. Reach inside the box and pull the end of the speaker wire out of the front opening.
Attach the end of the speaker wire to the speaker terminals. Place the speaker in the front opening and secure it with wood screws. Lay a bead of caulk around the exterior rim of the speaker.