The Art & Science of Audio & Video

Active or Passive Subwoofer?

What is the difference between passive and active subwoofers?

Active speakers get lots of exercise and passive ones tend to watch a lot of TV. Ready for the truth now? Passive and active essentially refers to whether or not a subwoofer (or any speaker for that matter) is self-amplified or not. So an active subwoofer will have a built in power amplifier that requires AC power just like any other piece of electronic gear in your system. The built in amplifier is typically accompanied by a variable crossover or fixed high pass filters for other speakers. These other speakers would be your main left and right speakers or possibly even all five left, center, right and rear speakers. The variable crossover will determine which frequencies the subwoofer will reproduce. If you set the crossover at let’s say 125Hz then the subwoofer will play all information below 125Hz. Now this isn’t exact but that is a conversation for another thread all together. A passive subwoofer will have a passive crossover in it just as your main speakers do. In your main speakers there is a crossover that determines what frequencies go to which driver (i.e. tweeter or woofer). Well in a passive subwoofer there is a crossover known as a low pass filter that determines the frequency at which the woofer will stop playing. There is much more detailed information on crossovers and their design elsewhere in the site if your interested.


February 27, 2008 - Posted by | FAQ's | , , , , , ,

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