In Phase XTB-828R 8" 300W Active Subwoofer with Passive Radiator and Class D Amplifer

What on Earth is a 'passive radiator'?
A Passive Radiator is a speaker with no voice coil or magnet, basically a speaker cone. This is not connected to the amp at all. The purpose of this speaker is to allow the trapped sound pressure in the sealed enclosure to excite a resonance that makes it easier for the speaker system to create the deepest pitches (e.g bassline). In short, it gives you the benefit of ported enclosures without the downsides. This leads to better sound quality, with a linear frequency response of the sealed cabinet and the higher output you get from a ported design. This is also achieved in a smaller size than the ported subwoofer. You also do not have the same issues with port noise, and instead, you end up with a smooth bass.

Class D Amplifier
A robust, compact and efficient Class D amplifier is mounted to this enclosure. This is the driving force behind the sub. Only the finest components in it's category will do. Offering up to 400W peak and 200W RMS Power

Compact Design
This sub is only the size of a small desktop computer case. This small footprint allows the user to add thumping bass without compromising space in the boot.

Superior Subwoofer Cone
The glass fibre subwoofer cone is purpose built for this package, it is lightweight, durable and rigid without compromising sound quality. A lot of market leaders have a generic subwoofer (from their range) then they build a box to suit. Which works to an extent, this package offers you something more unique and performance based .