There are other factors to consider!
Having built hundreds of enclosures over the years I have found that volume and type of enclosure (ported, sealed or whatever) play just as much of a role in overall sound quality and SPL (loudness of bass) as the placement of the enclosure. For instance, if you build that enclosure and face the subwoofer forward, you may be disappointed with the results. Face the sub backwards and you may be shocked at the output in comparison.
Some general rules of thumb when designing and building an enclosure:
- I always try to go on the larger size when it comes to recommended enclosure volume (ie: specs say .5 - 1 cubic foot...I try very hard to get as close to a cube.). You will usually be able to hit lower and get louder this way with some exceptions to the rule.
- Go ported if you can! You'll usually always hit lower and louder. You may not need as much power for the sub if you port as well (contrary to theory)
- If you must go small, use some polyfill in the enclosure to get a bit more bass extension.
- When making a fibreglass enclosure, please don't use anything less than three layers of glass for anything up to 500 watts. High power subs will need even more layers.
There are many other factors to consider as well. Power, crossovers, EQ and subwoofer parameters are all very important. If you need any help with design, you know where to find me.