No audio enthusiast would ever consider either a home or car sound system without incorporating a subwoofer. A subwoofer enhances the lowest bass notes in the music. This requires lots of power and higher quality specifications:

Impedance: Higher impedances are easier for an amplifier to "drive," or power.

Materials: sound-producing cones needs to be stiff, yet lightweight. Look for Kevlar or polypropylene. Metal cones are good but tend to be more expensive. Surround material that attaches your driver to the metal frame holding the speaker should be light, flexible and strong. Good surround materials are rubber or plastic composites.

Free-Air or Boxed Enclosure: This refers to how the sub is mounted. Free-Air enclosures have the sub speaker mounted to the back seat, or the rear shelf, using the trunk area as the enclosure.

Free-air systems save space and have flat frequency response. The sub speaker needs to be designed for this purpose. For best performance, the trunk should be air-tight when closed.
Boxed enclosures have the speaker mounted within a box with or without a "port" or a tuned bass opening. The port size and the box's volume (in cubic feet), needs to be matched to the speaker.

Sensitivity: Higher number, efficient speakers help maximize the performance of your amp.

Frequency Response: Look for lowest frequency response close to 20 hertz

Peak Power Output:

Volume Acoustic Suspension: Lower numbers are better.

Fs: The frequency at which a speaker naturally resonates in free air, measured in hertz, lower numbers are better.

Xmax: the measure of a speaker cone's maximum excursion in one direction while maintaining a linear (non-distorting) behavior. This is measured in millimeters, and larger numbers are better.

A great tool to determine what size speakers fit your car

Best SubWoofer Brands

NEXT: Integrating Your Apple iPhone With Your Audi

Get car audio systems on