A sealed subwoofer is a speaker that is enclosed completely within a square-shaped box. It is called "sealed" because the entire enclosure has no openings, except for the hole intended for the speaker's cone output. Many enclosures are available for subwoofer support and bass enhancement, but sealed subwoofers are one of the most common and affordable types.
Subwoofers produce the low bass sounds typical of rock and roll music. Home theater and car stereo systems often match high frequency speakers, such as tweeters, with a subwoofer to generate a depth to the music. Amplifiers are another component that enhances the power output from the subwoofer. A sealed subwoofer offers the best low bass frequency range for many musical genres, negating the need to adjust the speaker's sound output from song to song.
Sound waves within the enclosure are constantly bouncing against the walls and the cone's back end. The sound wave pressure against the cone generates a controlled vibration for a crisp bass output. This controlled motion allows the user to apply more power, such as through an amplifier, for increased volume and pulsation.
Lack of space is often a concern for both home and vehicle speaker installations. The sealed subwoofer does not require a lot of space for the enclosure, as opposed to the much larger ported subwoofer enclosures. There is more versatility during sealed subwoofer installation, allowing the user to place the speaker behind a couch or pushed into the corner of a vehicle's trunk. The subwoofer's vibration will still permeate throughout a space, even if it is hidden behind furniture or confined in a car trunk.
People on a limited budget can easily construct their own sealed enclosure; the only expensive purchase for the sealed subwoofer would be the actual speaker assembly. Fiberboard is readily available in home improvement stores for creating the enclosure walls. A person can cut the fiberboard to any desired dimension with power tools, securing the speaker to the enclosure with screws. A customized enclosure shape can be created for odd spaces, such as in a small or compact car.
This sealed enclosure type also has the ability to offer lower bass sounds compared to other subwoofer boxes. The acoustics within the enclosure allow low octaves to emanate strongly, as opposed to being canceled out through lack of vibration. This large bass range makes the sealed subwoofer appealing to music enthusiasts who listen to everything from rap to classical music.