The cabinet or structure of a speaker into which the various speaker elements (the drivers, the crossover, the binding posts, etc.) are placed and attached. peaker enclosures can be essentially any shape and any size made up of almost any material. Most speaker enclosures are made of MDF (medium density fiberboard) and then covered in a thin wood veneer or some other coating. Some cabinets are made of plastic or metal and some even use concrete, Corian, or other highly rigid materials. nclosures generally should be very well braced with internal strengthening members and fairly thick cabinet walls. Enclosures should be inert so as not to color the sound by vibrating with the speaker drivers. They must also be designed to function properly with the speaker drivers placed in them (for example a large woofer for a subwoofer will not perform optimally in too small an enclosure). There are as many variations on speaker enclosures as there are speakers. here are generally no hard and fast rules for what makes a good enclosure other than the resulting speaker sound good (in order to accomplish this there are certain mathematical formulas for matching a speaker driver to the proper volume enclosure). When purchasing speakers, however, look for enclosures that are solid and do not sound hollow when you tap them with your knuckles. Enclosures should be sturdy and well built. A heavy enclosure does not ensure a good enclosure, but often a heavier enclosure is more solid and more inert and so may have some bearing on your decision.