This instructable is about how to make a pair of good sounding speakers with little knowledge of carpentry. Lets get started with this instructable.
Step 1: Supplies
For this project, you're going to need some 1/2 inch wood, some balsa wood, small nails or tacks, a hammer, wood glue, hot glue, a drill, a 3 inch speaker pre wired, a screw driver, a measuring tape, a square ruler (not mandatory), 4 1/2 inch long screws, geometry compass, marker, hack saw, pvc saw (not mandatory), 1/2 inch pvc pipe, and a sanding block with low grit sandpaper (60 grit is what I used). You will also need a vice or clamps.
Step 2: Prepare Wood
Cut out these slices of wood: 4 4 x 5.5 inch pieces, 2 4.5 x 5.5 inch pieces. Some messing around with the hacksaw may be needed in order to cut out the larger slices. Once these are cut out, they can be sanded to be as close to perfect as possible. Cut one of the 4 x 5.5 pieces out of the balsa wood. The balsa wood piece will be used for the top.
Step 3: Cut Speaker Hole
This step is easy if you already have a hole saw the same size as your driver, but otherwise you can use a compass and hack saw to create the hole. Cut the hole in one of the larger 4.5 x 5.5 boards. To determine where to put the point of the compass, find the center of the wood, and then measure about 1/2 inch higher than the length of the radius of the speaker. When measuring the speaker, measure from the edge of the foam to the edge of the foam, so that the speaker won't just fall through when it is time to be installed. To cut the hole using a hack saw, drill a hole wider than the blade on your hack saw, and then take the hack saw apart, put the blade through the hole and put it back together, and cut the circle, then disassemble the hacksaw and take it back out of the piece of wood when you are done. (The hacksaw method is easier said than done)
Step 4: Assembly
Mount the speaker into the 4.5 x 5.5 inch board using 4 1/2 inch long screws. Next drill pilot holes for the nails. Drill them on the 4 x 5.5 boards. Use a small drill bit. Position them by eye, or if you want, measure them. Next put the 4.5 x 5.5 board with the speaker into the vice, with the long side facing up. Then apply glue, and nail the 4 x 5.5 board to the 4.5 x 5.5 board. Then flip it over and do the same thing. After that you can drill a hole in the other 4.5 x 5.5 board for the wire to go through. Now feed the wire through that hole and apply some glue to it on both sides, now line it up and nail it in. Now you can take the final board that is not balsa wood, drill pilot holes through it, glue it to the bottom of the box, and nail it.
Step 5: Tuning Port
Now take the piece of balsa wood, place the piece of pvc pipe onto it as shown in the picture, and using a marker, mark out where the hole should be cut. Make sure to make the hole 1/2 inch from each edge so that the wall of the box doesn't block the pvc pipe. Use the same method to cut this hole. Now cut the pvc pipe down to 7 inches, and just stick it in temporarily. It will be glued later. Once the pvc pipe is mounted, you can glue and nail the balsa wood, to the rest of the box.
Step 6: Hot Glue and Finished!
Now just fill in all of the cracks where air leaks out with hot glue, and secure the port with hot glue. Also write the power handling and other specs. Just build another one, and hook them up to an amp, and enjoy the nice bassiness of these 37 hz tuned speakers. If you want the ports to not stick out of the top, you can cut the ports down a little bit. This will tune the speakers to a higher tone, but I wanted bassy speakers, so the looks didn't really matter to me. The ports do whistle when you play really low notes.
Step 7: Video
Note: Skip to 12:30 for the sound test.