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Now that the hangovers of New Years are over with and the credit card bills from Christmas area flowing in, it's getting that time of the year when all of us diehard audiophiles and bass heads start making plans for the upcoming season. Even if your not into the car audio competition scene, no mini truck is complete without a system that makes maw-maw and paw-paw in the next lane shake their heads in aggravation cause your making them have to turn down there hearing aids and the mirrors are shaking on their 1986 Bonneville. This month and next we are going to take a look at the art of box building. Notice I said art. The art of box building is not screwing a couple pieces of ½" plywood together and expecting your subs to perform to the best of their ability. To build a box you must first understand the application at which your speakers are going to perform best in. The size of an enclosure is going to be determined by the Q factor of the speaker. Since most people don't understand what a Q factor is, the sub maker will normally enclose a pamphlet with your new sub that is going to describe what type of enclosure and size and type enclosure best fits your new subIn the past several years sub enclosures have taken on a total new design approach. Sub makers tried everyway possible to get the most out of smaller boxes and smaller subs. But when it is all said and done there are two types of sub enclosures that truly have stood the test of time. Sealed and ported or vented if you want to call it that. Anther very popular box is the band pass enclosure. A sealed box is just what it sounds like a box that no air can escape from. The box is completely sealed and no air is able to leak from the enclosure. When building a sealed enclosure you want to make sure every cut is precise and there is no way air can leak. Use wood glue on all your joints and coat the seams with a good dose of liquid nail or caulking. Ensure that the hole you cut for the speaker is as tight of a fit as possible. The size of the enclosure is how you tune the enclosure for a specific frequency you might want. When building the box keep this in mind the smaller the enclosure the higher the frequency the sub will produce, and larger the enclosure the lower the frequency the sub will produce. Smaller enclosures are more efficient and can handle more power then larger enclosures. The size of the box is best determined by the manufacture.
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A ported or vented enclosure is just that, it is a sealed enclose with a hole or port in the enclosure. This port is used to tune the enclosure to a specific frequency unlike a sealed enclosure that uses the box size to determine the frequency of the enclosure. Although ported enclosures are not as efficient they often sound better musically. One thing to remember is that the port will take away from the enclosures airspace so when you port and enclosure you must add to the size of the enclose for the lost airspace the port is taking up. The size, diameter and length of the port is an exact science, if it is to long to short to big to small the sub is not going to perform to it's ability and the sub actually can be damaged. I recommend only using a ported enclosure if the sub maker recommends this type of enclosure and includes the exact box specs and port specs in the sub instruction pamphlet. Another box that I really don't like and wish would go away is the band pass enclosure. The band bass was originally designed for use in situations were crossovers were not going to be used and just like its name suggest it allowed a certain band width to pass or be heard. These boxes are very damaging to your subs because in most cases you can't hear the distortion that is being produced by the sub. Distortion produces heat and heat causes your sub to be destroyed. Heat is the number one factor that kills subs. You can not simply go out and buy a prefabricated band pass enclosure that is not designed "SPECIFICLY" for a sub and expect it to work it can and will destroy your new subs. Next month we will look at the specific and actual box building process. There are several box building programs available for the PC but ranger anywhere from a couple hundred dollars to a couple thousand dollars. Next month we will take box building step by step. If you have any questions concerning box building or any car audio related matter feel free to drop me an email I always try to help whenever I can. Until next month remember "If the mirrors aren't shaken you been taken". Ben HusserSSM: Laynbdy laynbdy@midsouth.rr.com
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