Project Preparation

• 1). Choose the loudspeaker. You need to know the size of the loudspeaker--15 or 18 inches in diameter--before you can begin designing the box.
  
  
• 2). Get speaker design software. Speaker design software exists for Windows, Linux and Macintosh operating systems. WinISD is a free, popular download for Windows computers.
  
  
• 3). Apply the Thiesle/Small parameters. Thiele/Small (T/S) parameters provide all the relevant measurements for determining box dimensions. T/S parameters are included with the purchase of any quality loudspeaker.
  
  
• 4). Buy acoustic foam for damping the interior of the box.
  
  

Building the Perfect Box

• 1). Print out the plans from the speaker-building software.
  
  
• 2). Cut the box panels from the one-inch birch plywood as indicated by the plans. Use a table saw, or have a store cut the pieces to size for a nominal fee.
  
  
• 3). Assemble the side panels, bottom panel and brace. Additionally, countersink 2-inch wood or drywall screws in each joint. Clamp the box with furniture clamps and let it dry for six hours.
  
  
• 4). Cut out the back panel for the plate amplifier. Test fit the back panel to the box assembly. If the fit is flush, glue and screw clamp the rear panel to the box. Allow to dry for six hours.
  
  
• 5). Attach the top piece. Apply glue, secure with wood screws on all sides and allow to thoroughly dry.
  
  
• 6). Apply a bead of clear silicone rubber caulk to all interior joints. Allow to dry for 10 to 12 hours. Then glue acoustic foam to all interior surfaces of the box.
  
  
• 7). Cut out the circle for the loudspeaker in the front panel. Use a hole saw, router or circle cutter in a drill press.
  
  
• 8). Glue and screw the front panel to the box. Clamp the front panel. Through the opening for the speaker, caulk the inside seams of the front panel. Allow 12 hours for the silicone rubber caulk to thoroughly dry.
  
  

Finish and Installation

• 1). Sand the finished box with a sanding block. Fill the countersunk screw holes with wood putty. Sand again.
  
  
• 2). Install plate amplifier to the read panel. Use 12-gauge connecting cable, and connect the cable to the speaker contacts on the plate amp. The cable should be eight inches longer than the cabinet depth to make connections to the loudspeaker easy.
  
  
• 3). Apply stain, paint or wood veneer to finish and protect the box. Consider this a piece of furniture that should last 20 years.
  
  
• 4). Install the loudspeaker in the front panel. Connect the cable from the plate amplifier to the speaker contacts. Use Phillips wood screws to secure it to the front panel. Apply a bead of non-drying caulk between the front panel and the speaker perimeter to ensure an airtight seal.
  
  
• 5). Position the subwoofer where bass performance is best.