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Connecting a passive subwoofer

Discussion in 'Cables & Switches' started by jtwn, Feb 17, 2004.

  1. jtwn

    jtwn
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    Is there anyway how i can connect my passive sub to my denon 1604 receiver? The sub is from the Sony Dav-s550 and uses two wires connected to some odd plug which i guess is only for those Sony package receivers.

    Would cutting the wire and putting it in a phono plug work?

    I cant wait for my speakers to come, so would just like to try it out with the speakers from my other system you see!

    Anyone?
     
  2. Ian J

    Ian J
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    A passive sub has no amplifier of it's own and is fed by an amplified signal from the amp. Possibly you could cut the plug off and connect the bare wires to the speaker terminals on the amp but I am not a techie and wouldn't know which ones to connect to where.
     
  3. jtwn

    jtwn
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    Thanks for your reply.

    Yeah, ive tried cutting open a phono plug and connecting the wires from the sub to it but there was just no output.

    So should i take that it just wont work? Or would there be a way other than connecting it to just another speaker terminal (which obviously doesnt sound too good).
     
  4. bobbypunk

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    if you need to do it it may work from R+ and L- or R- and L+
    but it won't sound great. Tell the amp there is no sub.
     
  5. Nimby

    Nimby
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    I wouldn't recommend you connect your passive sub to a left and right speaker terminal. If it doesn't actually cause damage you will not be getting a proper full range signal to drive your sub. The sub will be seeing the difference between the channels. Rather like the old Hafler surround sound system.

    A passive sub has to be driven by an amplifier via a speaker cable from one set of speaker terminals. If you don't intend to use a centre speaker you might be able to use that channel to drive your sub. But if you are getting a centre speaker forget the passive sub and start saving hard for an active sub.

    I really can't recommend that you try to drive your passive sub in parallel with one of your main speakers either. It is one hell of a load on that amp channel. Not only would the amp be seeing a very low impedance but you would be trying to move a lot of air with two speakers using the full frequncy range. That takes an awful lot of power from the amp and it won't like it.

    Passive subs work best when running in parallel with carefully matched small satellites or driven from their own dedicated channel of a power amp. Or a completely seperate power amp. But you'd need 2 pre-out sockets from your pre-amp to do that (I believe).

    NIMBY
     
  6. jtwn

    jtwn
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    Thanks for your replies. Well i may just end up to connecting it to one of the normal speakers just for now, but when i connected my sub to another old stereo amp of mine and to a cd player through the 3.5mm lineout to just the left channel phono, and then connected the sub to just the left channel it worked relatively good with the bass up and treble down with the stereo amp.

    But when i connect the pre out to the left channel phono on my stereo amp, i get nothing through the sub.

    Anybody know a possible solution?

    Thanks
     
  7. jtwn

    jtwn
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    OK ive realised i have to turn up the volume on the stereo amp really loud, put the bass is pretty nice when up loud.

    The sub's impedance is rated at 2ohms or 3ohms (think its 2) and the rated inpedance for speakers on the stereo amp is 4ohm onwards.

    I guess its going to be terribly inefficient but could it damage my stereo amp or the sub? This is only until i have the money for a new sub.


    Ta
     
  8. Nimby

    Nimby
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    If it's rated at only 2 ohms it will be quite a load for most amps if driven hard. It's an even better reason not to run it in parallel with another speaker. The combined impedance would be probably be close to 1.3 Ohms if the other speaker is a 4 ohm one! Take it easy with the volume control or you may fry the amp if it doesn't have thermal protection circuitry. Though some amps are more tolerant with low impedances than others. I really wouldn't want to take the chance myself. My DIY passive subs are rated at 8ohms and they still managed to trip my power amp when driven in parallel with my floorstanders. So be a bit careful.

    NIMBY
     

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