• Subwoofer boxes hold subwoofers.speaker element image by bright from Fotolia.com
  
  While there are a wide variety of sizes and styles of ported subwoofer boxes, they all share a common construction and common principles. Most important, subwoofer boxes should always be constructed with the proper materials. Choosing the wrong materials will result in a box that creates low-quality sound and will not last very long. Building a quality subwoofer enclosure can be easy, and can allow you to add a customized touch to your car audio system.
  
  

Choose the Proper Materials

• A quality subwoofer box requires the use of particular materials. Medium-density fiberboard is a must for subwoofer box construction. This fiberboard should be 3/4-inch thick, which is a good balance between strength and weight. A subwoofer box should also utilize 2-inch screws and carpenter's glue to fasten the the fiberboard together. A terminal cup should be used on the backside of the subwoofer box to create a connecting point between the subwoofer and the amplifier. A port tube is essential to create a ported subwoofer box. A port tube is usually constructed of plastic and vents the subwoofer box for maximum volume and deeper bass notes. A final material that is used in subwoofer box construction is silicone caulking, which helps create a seal along the seams.
  
  

Build the Subwoofer Box to the Correct Size

• To create maximum performance, a subwoofer box should be built to the correct size. A subwoofer box should accommodate only one particular size of subwoofer. Subwoofers come in varying diameters from eight inches to over 20 inches, and attach to the front of a subwoofer box. It is also important to design a box that is deep enough to hold a subwoofer. Some subwoofers are much longer than others. A subwoofer box should also be constructed with an interior volume that is recommended by the subwoofer's manufacturer. Without the correct interior volume, the quality of the sound that a subwoofer plays will suffer.
  
  

Create a Tight Seal Between Seams

• It is important to have a tight seal between the seams of a subwoofer box. Although ported subwoofer boxes are not airtight, sealing the seams between each sheet of fiberboard will result in a sturdier construction. Also, air should not escape between the seams of the subwoofer box because that could alter the sound of the subwoofer. Use a small hand-held tube of silicone caulking to seal the hard-to-reach corners of the subwoofer box.
  
  

Install an Exterior Carpet

• Although not essential, installing a carpet on the outside of the subwoofer box will make it more aesthetically pleasing and help prevent the sharp edges of fiberboard from damaging the contents of your trunk. There are a wide variety of carpets that are manufactured specifically for subwoofer boxes and can be installed using a spray adhesive.