Driving unpowered subwoofer with extra amp channels

Discussion in 'Archived Threads 2001-2004' started by Jorge M, Aug 3, 2001.

  1. Jorge M

    Jorge M Stunt Coordinator

    Feb 27, 2001
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    This is my first post, but I've been reading the forum for ages. I'm planning on getting a whole new surround setup (receiver, 5 speakers, sub). I like the SVS subs, but I don't have an "old receiver lying around" to power it. Most receivers nowadays come with 6 or 7 channels of power. Since at this point I can't afford more surround speakers, could I use some of those extra unused channels to power the sub? I figure in order to do this I would have to run a patch cable from the preamp sub output to one of the inputs and run speaker wire to the sub from one of the unused channels, but then it's impossible to set the receiver to more than one input at the same time, isn't it? Or maybe there is a receiver that lets you reassign internally a surround channel to a subwoofer channel?
    I could always get a powered SVS, but that would just be too easy, wouldnt' it?
  2. Bob McElfresh

    Bob McElfresh Producer

    May 22, 1999
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    Hi Jorge. Welcome to HTF! [​IMG]
    No you cannot use the extra channels to power a sub.
    For one, when your receiver is reading the DVD signals, it will ignore the other inputs so it would not amplify the LFE signal.
    For another: the sounds that take the MOST power is the lower-frequency sounds so you would be draining your receiver to drive the un-powered woofer. (Think about it: you have 100 watts per channel in your receiver. But most self-powered subs have 200 - 2,500 watt power supplies.)
    So your choices are:
    - Buy another receiver with line-level inputs to drive the woofer (not a great option)
    - Buy a monoblock or 2-channel amp to power the woofer (good idea)
    - Buy the self-powered SVS (great idea because you get lots of options, crossovers, inputs/outputs, etc).
    Hope this helps.
  3. Wayne A. Pflughaupt

    Aug 5, 1999
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    Katy, TX
    Real Name:
    quote: Since at this point I can't afford more surround speakers, could I use some of those extra unused channels to power the sub?[/quote]
    You can if you have pre-out and main-in jacks on all channels. You could send the LFE out to the main in of one of the surround channels, and hook up your sub to that channel’s speaker terminals.
    However, like Bob mentioned, the sub will be under powered, and it will likely limit the headroom of the other speakers. Whether or not this is a problem depends on how hard you normally have to push your receiver.
    Wayne A. Pflughaupt
    [Edited last by Wayne A. Pflughaupt on August 03, 2001 at 11:14 PM]
  4. Michael P

    Michael P Agent

    Mar 2, 1999
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    I'm not sure about how to use your existing receiver to power your subwoofer, but it was my understanding from the SVS website that there subwoofers could be driven by any old receiver, 80 to 100 watts with no problem. I have an old onkyo 910 that I'm thinking about using to drive a SVS sub. Maybe someone else will chime in and let me know if the 80?? watts I think will be enough to drive it. Thanks!!

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