|If you've already purchased a driver that you
want to use in a subwoofer design, then chances are that the manufacturer has provided one
or more enclosure designs for the driver. For the least amount of worries, it's usually
safe to go with the manufacturer's recommendations. If a specification sheet was not
included with the driver, try calling the manufacturer directly.
If the manufacturer has not provided recommendations for suitable enclosures for the driver, then you'll need to use the Thiele/Small parameters for the driver in order to determine the optimum enclosure for it. Sometimes these parameters are provided along with the driver, but if you can, you should measure them yourself in order to get the best results with your subwoofer design. You can use the method given on the Measurements Page to measure the Thiele/Small parameters for your driver, then use these results to determine the best enclosure design that meets your needs.
Another avenue of information is the rec.audio newsgroups, or the BASS and DIY Loudspeakers mailing list. Chances are that someone else has already built a subwoofer with a driver like yours. No need to reinvent the wheel!