Part 1: Assembling the CabinetStep 1. Start by measuring and cutting out the first three 24"x18" Baltic birch pieces—the cab’s front and sides—using a table saw or jigsaw. Make sure you follow the old woodworker’s creed: “Measure twice, cut once.”
Step 2. Now measure and cut out the 24"x17" Baltic birch piece (the rear panel), followed by the 18"x18" roof and 17.5"x15.5" speaker mount.
When you’re done, you’ll have six pieces of wood that form the cabinet (Fig. 5).
Step 3. Now we need to cut matching windows into the front, sides, and removable rear panel. Use your table saw or jigsaw, and make sure to follow the measurements shown in Fig. 3.
Note: The 13"x9.5" window cutout is illustrated on one of our three 24"x18" pieces, and on these, the cutout is inset 2.5" from the top and sides. We want the identical 13" width for the window on the 24"x17" rear panel; this requires a 2" inset from the sides of that narrower rear panel. (The top inset remains 2.5".)
Fig. 6 shows the three matching front and side panels, and the rear panel (far left)—all with identical window cutouts.
Step 4. With your sander, work the edges of each panel until they are smooth to the touch. If you over-sawed a little on the windows, consider filling up the corners with wood putty so it looks neat.
Step 5. Grab the 17.5"x15.5" speaker board and find its center. Before you begin cutting, measure the flange of your 12" speaker and then subtract the flange measurement from 12. (In my case, the flange was 3/4", so I was left with 11 1/4" or 11.25" for the speaker cutout.)
Divide that number in half (5.625" or 5 5/8" for my speaker) and you have your radius. Using a compass, measure out that radius from the midpoint of the 17.5"x15.5" speaker mount, and then carefully draw a circle.
Step 6. Using a router or drill bit, drill a pilot hole near the edge of the circle. Then from that hole, carefully cut the circle with your jigsaw (Fig. 7). After that, sand the cutout edges smooth.
Step 7. Now we’re going to attach the slats to support the speaker mount to the three 24"x18" pieces. Measure 2" down from the window of one of these pieces and apply a stripe or two of wood glue on the wall—not on the slat itself. Next, affix the slat to the wall (Fig. 8), making sure the slat is perfectly level.
Do this to all three 24"x18" pieces, and be sure to measure each slat’s location to confirm they’re identical. If you want extra strength, add four staples to each slat.
Step 8. Once the glue has dried, it’s time to begin installing the speaker mount to the front and side walls. Take one of your 24"x18" pieces, place it upright, and put a stripe of glue on the top of the support slat (Fig. 9). This becomes the front of the cabinet.