When it comes to Subwoofers the enclosure you put them in is just as important as the driver itself. Whether you use a sealed box for a tight controlled sound or a ported or bandpass box for greater output. Whether you choose to build the box yourself or if you purchase a factory box or get a local shop to build you one there are a few things you should know. When you build a box do the calculations first ( measure twice and cut once ). Whether you use the manufacturers recommendations or download software from the bottom of the page it is important especially in bandpass and ported designs to get the volume of the box as close to perfect as possible. Once you have the volume of the box and have decided on the shape go out and buy good solid mdf/customwood , if you are building a box for two 12 inch subs or more you will require at least 18mm thickness. The best way to join the box is using dove joints instead of butt joints if you don't know the difference ask the guy at the hardware store. Using good quality screws designed for customwood first glue then screw the box together. If you are going to be using two 12's or more then it is a really good idea to brace the box on the inside, the easiest way to do this is to scew in solid pieces of customwood across the middle of the box. Making sure you deduct this volume from the volume of the box, the same for ports if you are doing a ported box, you must deduct the ports from the volume of the box. Once the box is together use silicon sealant to seal up the inside of the box. If you are going to put a fancy speaker terminals on the side of the box which is a good idea for looks and ease of wiring, be sure to seal that well too. Line the back wall of the box with dacron or similar to reduce standing waves and reduce general box noise. Do not over stuff your box or you will suffocate your subs. Then before you put your drivers in decide whether you are going to carpet your box or use stretch vinyl or leave it as it is. The idea of this is to reduce noise from the box further and to make it look good, I am quite keen of using stretch vinyl because you can place cutouts of you fav logo or similar underneath to create a classy looking box with your logo raised on the outside. If you use stretch vinyl its a good idea to place dacron of felt underneath to make it softer and smoother. Okay now all you have to do is screw your subs in sealing them with double side foam tape if they don't come with a foam edge, DONOT seal with silicon or you will never get them out again. Now try and fit it in your car and go cruising...Below are some good links to give you ideas and advice from people who know...
If you want software for designing boxes get it here...the most pop is probably perfect box ( perf.zip )
Good link for FAQ on subs and boxes
Polk Audio have some good box designs
JL Audio have a tutorial section on subs and sub boxes ( very informative )
Steve's Sub Page, little more on the subject of sub enclosures
g.hartley@xtra.co.nz
