how do I hook up two passive subwoofers?

Discussion in 'Speakers & Subwoofers' started by JohnBrianW., Dec 4, 2004.

  1. JohnBrianW.

    JohnBrianW. Stunt Coordinator

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    I have a dedicated 2 channel integrated amp (no amp out). I want to hook up 2 passive subwoofers, one for each speaker but am unsure of the best way to wire them.

    As I see it, I have 2 choices:

    a) run a shotgun configuration straight off the amp with 1 cable going to the speakers and 1 to the the subwoofer.

    b) run a cable to the subwoofer, and then from the subwoofer to the speaker, using the subs x-over.

    Is one a definite no..no? Or is one preferential?

    thanks
     
  2. frank manrique

    frank manrique Supporting Actor

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    quote:

    I have a dedicated 2 channel integrated amp (no amp out). I want to hook up 2 passive subwoofers, one for each speaker but am unsure of the best way to wire them.

    As I see it, I have 2 choices:

    a) run a shotgun configuration straight off the amp with 1 cable going to the speakers and 1 to the the subwoofer.

    b) run a cable to the subwoofer, and then from the subwoofer to the speaker, using the subs x-over.

    Is one a definite no..no? Or is one preferential?
    __________________________________________________ ________

    First of all, do you have to use that integrated amp?

    Second, you say "passive" subs yet you mention a crossover. Where does the crossover come into the picture?

    You can actually connect (option A) the subs to your main speakers (parallel), but there will be no crossover point between them; the resultant impedance will be halved, of course, so it might be an issue of some concern.

    Hope this helps... [​IMG]

    -THTS

    "...hi, my name is Frank...and am an SVS bassaholic..."
     
  3. JohnBrianW.

    JohnBrianW. Stunt Coordinator

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    Hi Frank,

    Thanks for the response. The subwoofer does have a crossover.

    Did you mean option B? Or am I miss understanding you.
     
  4. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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    It all depends on the configuration of the crossover and the terminals on your passive sub. The "crossover" inthe sub box may be just a low pass filter with the speaker lugs tied together, in which case options a and b amount to the same thing. If the "speaker out" lugs on the sub lead from a high pass filter in the sub box, then the trade off for option B is as follows:

    Mains less burdoned by deep bass (good)
    Load the amp sees is not halved (good)
    Mains signal must pass through the sub's passive crossover components (probably cheap coils and caps) (bad)
     
  5. joseFMJ

    joseFMJ Stunt Coordinator

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    Choice (a) would be something like bi-wiring, however the full audio spectrum would be going to the regular speaker. Both the subwoofer and the main speaker will be reproducing the same notes in the lower audio range, which may lead to cancellation or notes doubling.
    Option (b) is preferable if your subwoofer Xover has a high pass network. So the amp outputs goes to the subwoofer crossover, which splits the bass signals to the subwoofer and passes the rest of the frequency(upper bass, mid and treble) to the main speaker.
    I take it you mean you have a passive sub (no internal amp) with a passive crossover network?
    Whichever way, option (b) as I described it is the correct way. Best way would be to biamp, using electronic crossover and separate amps for subwoofers and main speakers. For this you would need a preamp or intregrated with preouts and 2 stereo amps (or 1 additional amp if using and Intreg.), the preamp feed the electronic crossover which in turn feed the subwoofer amps the low bass, and the main speaker amps the rest of the frequency.
     
  6. ChrisBee

    ChrisBee Stunt Coordinator

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    I ran two passive subs in parallel with high quality shoe-box monitors for some years. One to each channel fed from a wimpy stereo amp. The amp used to get very hot. I expect it was only seeing about 3 Ohms per channel! Eventually it died! :b

    I would suggest you get a couple of cheap subwoofer plate amps with built-in crossovers. (and low pass filters) With high level connections to drive your subs. (Via speaker terminals)

    Whether you want to lighten the load on your speakers will depend on how good the speakers sound deprived of bass. But at the mercy of whatever crossover components are used in the sub's plate amps.

    For music or film I'd personally run your speakers full range. Then feed the subs by high level (speaker cable) connections as a seperate stereo pair. (one to each channel L & R) It shouldn't make much difference whether you run the speakers off the same amplifier terminals as the subs. Or off the input terminals on the subs on shorter cables.
    Set up each sub close to its respective speaker for minimum cancellation. And use an SPL meter and test tones to balance the output from the subs with your speakers by adjusting the sub's gain controls and low-pass roll-off point. For a smooth transition between sub and speaker.

    ChrisBee
     
  7. frank manrique

    frank manrique Supporting Actor

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    quote:

    I ran two passive subs in parallel with high quality shoe-box monitors for some years. One to each channel fed from a wimpy stereo amp. The amp used to get very hot. I expect it was only seeing about 3 Ohms per channel! Eventually it died! :b
    __________________________________________________ _______

    Chris...tsk, tsk, tsk. I thought you better than that! [​IMG]
    Just Kidding, Pal... [​IMG]

    Actually, I also tried about the same arrangement--ran a pair of prototype Ryan Acoustics 8" bandpass passive subs and small speakers--but the small monitors (Rogers LS3-5As) have a nominal impedance of 15 ohms so I got away with it; my amp survived the ordeal! [​IMG]

    Merry Christmas, my friend!... [​IMG] [​IMG]

    -THTS

    "...hi, my name is Frank..and am an SVS bassaholic..."
     
  8. ChrisBee

    ChrisBee Stunt Coordinator

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    Small world Frank. I ran Linn Kans with homebuilt 6th order series bandpass with 10" SEAS units. The Kans are notoriously difficult to drive on their own. Adding 8 Ohm parallel subs was the death sentence on my poor little 30watt stereo amp!
    It sounded nice though. Even if the cooling fins did light the room on those darker evenings. When I cranked it on Vierne's organ music. [​IMG]

    [​IMG] Merry Christmas to you too Frank! [​IMG]

    ChrisBee

    PS Did I miss the pix of those 8 x 16-46's? :b
     

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