Editing Subwoofer (section)

===Amplification===
[[File:Aktives Subwoofer Modul.jpg|thumb|The internal components of an active (powered) subwoofer, showing the circuitry for the [[power amplifier]]]]

'Active subwoofers' include their own dedicated amplifiers within the cabinet. Some also include user-adjustable [[#Equalization|equalization]] that allows boosted or reduced output at particular frequencies; these vary from a simple "boost" switch, to fully [[parametric equalizer]]s meant for detailed speaker and room correction. Some such systems are even supplied with a calibrated microphone to measure the subwoofer's in-room response, so the automatic equalizer can correct the combination of subwoofer, subwoofer location, and room response to minimize the effects of room modes and improve low-frequency performance.

[[File:Final05jm1.jpg|thumb|left|upright|This rear panel of a powered subwoofer shows the [[heat sink]]s used to cool the [[power amplifier]].]]

'Passive subwoofers' have a subwoofer driver and enclosure, but they do not include an amplifier. They sometimes incorporate internal passive crossovers, with the filter frequency determined at the factory. These are generally used with third-party power amplifiers, taking their inputs from active crossovers earlier in the signal chain. Inexpensive [[Home theater in a box|home-theater-in-a-box]] (HTIB) packages often come with a passive subwoofer cabinet that is amplified by the multi-channel amplifier. While few high-end home-cinema systems use passive subwoofers, this format is still popular in the professional sound industry.<ref name=JBLSSDM />