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Amp For Passive Subwoofer

Discussion in 'Speakers & Subwoofers' started by Spottedfeather, Apr 19, 2018.

  1. Spottedfeather

    Spottedfeather Stunt Coordinator

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    I'm getting a subwoofer in a little while and will be using speakers that I already have. The subwoofer I have is a passive one with only a "fork" wire, one purple and one black. I know that I will have to use some sort of amp to run the rca out from the receiver to the amp and plug the sub into the amp.

    My question is this....what is a good, yet cheap, amp to look for ? All the ones I've seen so far have several outputs for speakers, often a left and right speaker output. Which would I put the sub wire into ?

    Also a short side note.....I've been reading that you can plug the wires of a passive subwoofer into the front speaker outputs of a receiver. How would you do this and would it really work ?
     
  2. JohnRice

    JohnRice Executive Producer

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    I would use a subwoofer plate amp. THIS is the cheapest one I found, but that place has a lot more to choose from. It's a little bit of a rigged system, but it's what I've done myself. You take the line level sub output from the receiver and connect it to one of the line level inputs on the amp. Then connect some speaker wire with wire nuts to the output on the amp. Not the connectors on the printed side of the amp, but the output wires on the back of the amp. Connect the other side of that speaker wire to your passive sub. You now essentially have a powered sub, just that the amplifier for it isn't inside the sub's enclosure. You'll probably want to try and hide that amp from view, if you can, like behind some doors that you can still get wires to. At that point, you have all the same adjustments on the sub's amp as any powered amp has.
     
  3. JohnRice

    JohnRice Executive Producer

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    I just noticed that amp I linked doesn't turn on/off automatically, which is a nice feature. THIS one does, as well as probably all the others. It also has an enclosed housing,which the other one doesn't.
     
  4. Spottedfeather

    Spottedfeather Stunt Coordinator

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    If my plan to get a powered sub falls through, I'll definitely keep this in mind. Quick question, though. My passive subwoofer only has two wires coming out of it, a purple positive wire and a grey negative wire. Would I put this into the left or right speaker output in the amp ? Also, that last amp you posted has weird connections on the back that don't look like the rca plugs that come out of a receiver.
     
  5. JohnRice

    JohnRice Executive Producer

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    Keep in mind, these are plate amps, which are what are used in powered subs. So, the plate side is the same as what you see on a powered bub. They can have a multitude of inputs, but you only use one of them. If you are connecting it to a surround sound receiver, you just connect an RCA cable to the LFE input, if it has one, or the line level input that's designated "Mono" if it doesn't. The output to the sub is on the back of the amp, and is just two wires, like with any speaker, and you add some speaker wire to connect to one channel, speaker level input on the passive sub. The output wires on that one amp just have spades on them. You either use a corresponding male spade connector on your speaker wire, or cut that off and solder and tape or connect it with wire nuts.
     
  6. Spottedfeather

    Spottedfeather Stunt Coordinator

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  7. JohnRice

    JohnRice Executive Producer

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    You said you found an amp, but the link is to a powered subwoofer.

    Most powered subwoofers have multiple ways they can be connected, but you only use ONE of them. With any current surround receiver, you'll connect the sub pre-out to one of the line level inputs, either L or R. That sub doesn't designate either for a mono input, so you can use either one. Some subs have an LFE input, and that's what you use with ones that have it. Then you turn the low pass dial all the way up to the highest setting, because you actually set that with the receiver. Usually turn the volume to half, or a little less, and then you actually control it's level with the speaker setup in the receiver.

    BTW, for the same money, THIS is ten times as good a sub as that Polk.
     
  8. Spottedfeather

    Spottedfeather Stunt Coordinator

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    I meant subwoofer....
     

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