"Active" Subwoofer

Discussion in 'Beginners, General Questions' started by Brooks, Jul 21, 2003.

  1. Brooks

    Brooks Extra

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    Basic question that I thought should go here rather than the speakers / subs page.

    Am I understanding correctly that an "active" subwoofer has its own power supply and plugs into wall power in addition to receiving sound voltage over the speaker wires?
    The advantage is more power available to move the cone - yes?

    Thus, a "passive" sub uses only the power on the speaker wire to move the cone - just like regular speakers?

    If I'm understanding correctly and I'm ready to buy is an "active" really that much better than a "passive?"
     
  2. John Garcia

    John Garcia Executive Producer

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    An active sub has it's own amplification. While you can supply signal to an active sub via speaker level inputs (wire), the preferred way would be to use a line leve (RCA) connection.

    With a passive sub, you are correct that the receiver now has to power the sub as well as the other speakers. Ideally, passive subs are usually intended to be used with an external amp, not driven directly off of your receiver, though it is possible. This is where an active sub is a large asset, as the passive sub will draw current from the receiver reducing the total amount of current available to the other speakers; this effectively limits your peak available power and works your receiver harder.
     
  3. Bob McElfresh

    Bob McElfresh Producer

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    What John said!

    Instead of 4 speaker wires, a self-powered sub can take a simple RCA cable from the LFE/Subwoofer output of your receiver.

    This frees power up for the other 5 speakers and allows the receiver to direct low-frequency sounds from all 5 speakers, and the ".1" channel to the self-powered sub.

    So while more expensive, self-powered subwoofers are more common, more popular and IMHO superior to passive subs.

    (And this comes from a guy who spend $1,500 per speaker to get towers with built-in 500 watt subs. These subs are now turned off in favor of a single SVS sub in the corner). [​IMG]

    (Hey, I was younger and did not know better)
     
  4. Brooks

    Brooks Extra

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    Pardon my pedantic newbiness but "self-powered" means "has internal amplification provided by 110v AC power from the wall?"

    That's the part I'm too dense to get - an active sub takes speaker wire or RCA from the receiver __AND__ wall AC power - yes?
    I'm building the room now so I need to get this one right.
    Thanks.
     
  5. Richard Travale

    Richard Travale Producer

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  6. Bob McElfresh

    Bob McElfresh Producer

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    On placement of subwoofers:

    There is a lot of info in the primer and in the "Speakers & Subwoofers" fourm on this topic.

    But in general, you want to locate the sub in the corner of the longest pair of un-broken walls.

    Run RG6 (yes, CATV coax) to this corner and pull enough wire to move the sub about 1/3 of the way along one wall. This will give you slack to play with positions later.
     

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