The Free-Air Subwoofer Enclosure

There are many types of subwoofer enclosures, which are commonly referred to as “boxes”, for your car’s stereo system. They vary with different types and size depending on the type of vehicle you have, the space available, and the type of sound you desire. An free-air subwoofer, also known as the “infinite baffle” subwoofer, is more or less designed for vehicles with smaller space available or for people who actually want to use their trunk for storage. It is preferred by many because of it cuts down on the cost and also on the installation time that you would go through building a sealed subwoofer box.

A free-air subwoofer enclosure is basically mounting the subwoofers to a board and then placed behind the rear seat or under the rear deck of the vehicle. The board acts as a barrier between the front of the speaker and the back, which keeps the sound from the rear making a path to the front and canceling itself out. The trunk acts as the entire box, so for the best performance, it is important to have an air-tight trunk seal. It is the simplest and easiest to follow design available to house your subwoofer.

The sound quality is great and easy to achieve because there are no strict measurements to follow. The only downside to this style of enclosure is that low-frequency bass will not be very accurate or define. You will also have to use a little of that extra trunk space for additional some additional amplification to make up for what it lacks.

Compare to Other Designs

The other types of subwoofer enclosures are: sealed, ported, aperiodic, isobaric, and band pass. A sealed box is the easiest to build and, by far, the most common. It has the best sound quality, but it will take up more room than a free-air subwoofer enclosure.

The ported enclosure has an air-releasing tube and is designed for re-enforced bass. It requires very a specific build or the sound quality will significantly suffer. Aperiodic enclosures lack in booming bass, however the bass is both tight and accurate. They are small and hard to design and tune. Isobaric subwoofer enclosures have the best bass for a small design. One of the subs is exposed so it is prone to damage. The band pass enclosure has more bass than the rest but it is over a narrower frequency range. These enclosures are also quite large.