Dual voice coil

By incorporating two 4 ohm voice coils into one speaker, Dual Voice Coil technology enables the same woofer to be used as a 2 ohm or 8 ohm impedance unit simply by changing it's wiring connection. This allows the speaker to be used in the widest variety of combinations and configurations.

 Enclosure types

Sealed Box -A sealed box is simply an airtight enclosure housing your subwoofer. A sealed box is best for any music that demands tight, accurate bass. Expect flat response, deep bass extension, and excellent power handling. A sealed box tends to need more power than a ported box. So, be sure you use an amplifier with ample wattage to get the most bass out of your sealed box.
Ported Box - A ported box uses a vent (called a port) which allows movement of air in and out of the chamber behind the subwoofer. This additional air movement reinforces low bass response. You get more output from a ported box than you would from a sealed box at any given amplifier wattage. Some people prefer the sound of ported boxes for rock, heavy metal, or any hard-driving music because they are a bit boomier than sealed boxes.
Free-air Subwoofers — A free-air system consists of woofers mounted to a board attached to the rear parcel shelf or placed in the boot against the rear seat. The boot acts as the enclosure housing the subwoofer. Free-air systems save space and have flat frequency response. The woofer must be specifically designed for free-air use, and the vehicle's boot must be airtight for the best results.

Frequency Range

The range of sounds from lowest to highest that the subwoofer is capable of reproducing. The figures listed with the drivers are supplied by Kenwood. The actual range you'll hear can vary depending upon the type of box and vehicle the subwoofer is installed in. Under most circumstances, a typical sub will play deeper than its published figures indicate. So, don't base your choice solely on this spec.

Peak Power

The amount of power the subwoofer can handle as a brief burst during a musical peak. You should not drive your subwoofer continuously with wattage equal to the peak power rating.

Power Range

An external power amplifier is required to drive any raw component subwoofer. Don't try to drive one with your receiver's built-in amp. The low number listed is the absolute bare minimum wattage required to get acceptable sound from the subwoofer. For best results use an amp that provides a power level (RMS, or continuous watts) in the upper part of the subwoofer's recommended range (RMS).

Powered Subwoofer

see 'Active Subwoofer' above

Sensitivity

This spec is quoted in dB SPL (Sound Pressure Level) The higher the number, the more efficient the subwoofer is at turning amplifier power into sound. Sealed box woofers tend to be less efficient than those designed for use in ported, bandpass or free-air applications, but they do offer you extended deep bass and high power handling capability.

Voice coil

The voice coil is the coil of wire in a loudspeaker that creates a magnetic field. With the help of other speaker components, the voice coil converts electrical signals into mechanical energy which is used to produce sound. The voice coil former is the part of the speaker around which the voice coil is wound. Many of the speakers on this site offer a heat-resistant voice coil to prolong speaker life.