 Subwoofers are becoming more and more important for the home theater experience. When you go to the movie theater, you are excited not only by the images projected on the screen, but the sounds around you. What really can impress you, though, is the sound you really feel; the deep bass that shakes you up and gets you right in the gut. A subwoofer is a specialized speaker that is responsible for this experience. These device is designed only to create the lowest of audible frequencies.
Passive Subwoofers
Passive subwoofers are powered by an external amplifier, in the same way as other speakers in your system. The essential point here is that since extreme bass needs more power to create low frequency sounds, your amplifier or receiver needs to be able to produce enough power to maintain bass effects in the subwoofer without draining the amp. How much power depends on the desires of the speaker and the size of the room.
Powered Subwoofers
To decide the problem of insufficient power or other characteristics that may be lacking in a receiver or amplifier, powered subwoofers are self-contained speaker/amplifier units in which the characteristics of the amplifier and subwoofer are optimally matched.
Note that all a powered subwoofer needs is a line output from a receiver. This device takes a lot of the power load away from the amp/receiver and lets the amp/receiver to power the mid-range and tweeters more easily.
Front-Firing and Down-Firing Subwoofers
Front-firing subwoofers use a speaker mounted so that it emanates the sound from the side or front of the subwoofer enclosure.
Down-firing subwoofers use a speaker that is mounted so that it emanates downward, towards the floor.
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