Basics

• The subwoofer is a speaker specifically designed to the reproduction of bass audio frequencies ranging from 20 Hz to 80 Hz. Depending on the type of subwoofer, it can go even lower than 20 Hz, which can sometimes be difficult for the human ear to hear. Subwoofers are made to accompany main speakers, which are speakers that typically produce the high and middle equalization measurements, also known as "EQ's".

Types

• The two main types of subwoofers are the passive subwoofers and the powered subwoofers. The passive subwoofer cannot be powered on its own and therefore uses an external amplifier. The powered subwoofer has a built-in self contained amplifier or speaker, and is powered once it is plugged in and turned on.

Enclosures

• The three main enclosures for subwoofers are sealed boxes, ported boxes and bandpass boxes. The sealed box is an airtight enclosure that houses the subwoofer and provides a tight, accurate bass delivery. The ported box uses a vent (or port) that reinforces a low bass response. This type offers a deeper bass sound than the sealed box and gives more output. The bandpass box is designed for "maximum slam." The subwoofer is mounted inside a dual-chamber box--one chamber is sealed while the other is ported--which allows the output of the bass sound to be extra loud with narrow frequencies.

Other Enclosure

• Another type of subwoofer enclosure is the free-air subwoofer. It is distinct from the main three subwoofer enclosures. The free-air system enclosure is designed with the woofers mounted to a board which is attached to the rear deck of a vehicle against the back seat. Sometimes they are also just placed in the trunk. The trunk of the vehicle is used as the actual enclosure. It houses and isolates the sound from the subwoofers back speaker, solving the sound cancellation problem of subs without a built-in enclosure.

Warning

• When installing subwoofers into your home entertainment system or in a vehicle, ask for expert advice on how to install them properly. A poor installation of the subwoofers could result in too much distortion, which could lead to permanent damage within the electronics of the system and loss of hearing.