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How to install TWO subwoofers ?

Discussion in 'Subwoofers' started by dUnKle, Sep 17, 2004.

  1. dUnKle

    dUnKle
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    Having owned a sub since the Rel Q100E came out I found the above sticky actually very helpful

    However does anyone have any tips on how to install two subs ?

    My othr half purchased me a Rel Quake as a present about a year back and I am still no convinced I have them set up to run at there best together

    I think that I should be using one to back up and support the front speakers and connect via the speaker level connections and then connect the other via the phono out (possibly also backing up the centre speaker as well)

    Question is, is this correct and which sub to do which duties

    Thanks in advance
     
  2. Ettepet

    Ettepet
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    With "search" you can find some help. Without an equalizer it can be a pain, from what I hear, so if you don't have one consider buying one.

    Subs halfway your sidewalls should be one of the things to try out, much depending on your rooms layout.
     
  3. recruit

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    Hello Duncan,

    I suppose it does depend on what sort of speakers you are useing Large or Small and if you want to run the front full range then the Rel's would be quite good at blending in with them with Hi Level Connections.
    But if you are running them with sats then probably a Y lead from sub out and calibrate independantly with an SPL,obviously location plays a big factor and also the delay set correctly or distance.
    I have been running 2 subs 1 front and 1 back but i have 2 outputs on my amp and can configure them either front or back also with a BFD connected to equalise and smooth the response.
    It's all down to preference and the main thing is to get it sounding good to you.

    John :)
     
  4. dUnKle

    dUnKle
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    Thank you

    My left/right speakers are B&W 603S2s whilst the centre is a CC6S2

    I currently have a Y splitter from my Denon A1D to both subs and with one sub connected to centre speaker and one to the left and rights

    All speakers set as large and bass sento both sub and speakers
     
  5. samhain

    samhain
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    Apart from going into the nitty gritty of cancellations etc. I set each sub upto 75 db then put both on at the same time, then dropped the amp gain to give an overall 75db gain.
     
  6. dUnKle

    dUnKle
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    Thanks - most helpful - will give it a try

    Which of the two subs would you think best suited to supporting the front speakers ?

    Also does anyone know what crossover to use for B&W 603s2s when run in large mode ?
     
  7. wookie

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    I use "large" speakers but run them as "small".
    I use three subwoofers in my system and they are all run from the subwoofer pre outs on my NAD T762, one pair of identical subs on a "y" lead.

    The two front subwoofers are just in between my front speakers and the big sub is next to the couch @ the back of the room.

    Setup, I have found to be quite easy.

    1) Use a test CD with frequencies in 20Hz increments or 10 if you can find one.

    I use an old car audio setup disk with sinewaves from 10Hz-20kHz.

    2) Set one sub in the room, Sit and listen....
    3) When happy with one sub, adjust the second sub to give the same output as the first but make sure the 1st sub is off.

    4) Run both subs, check phase and back off on the subwoofer trim level (you will have gained at least +3db) the phase is about right when the output becomes loudest in the listening position @ all or most freqencies.
    When I am happy with the phase and level of the front subs, I simply do the same on the 3rd from my the comfort of my couch.

    I have experimented with every configuration and find that I get the best (smoothest integration) with the three subs running off the subwoofer pre outs with all speakers set to "small" and an 80Hz low pass.




    If two channel is your thing, just use high level to both subs in parallel from the amp on "speakers B" if you have it and run in a "direct mode" or Analogue through the front ins on your multichannel inputs from a CD player.
    This will bypass your bass management settings in the AVR for music playback.

    Hope this helps...iTS WORTH A TRY works for me :smashin:
     
  8. dUnKle

    dUnKle
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    Thanks for that mate

    Think its just going to be a cse of working out which sub to do what

    The benefits of the Quake is that the roll off is actually marked in figures so should allow be to easier intergrate with the fronts
     
  9. Nimby

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    Benefit? I wouldn't count on it. Use snapbug's stepped sinewave tones and an SPL meter.

    Ideally you want both subs co-located for LFE and as a seperated stereo pair for music. Co-located simply means side by side for mutual gain.
    I used a large pair of passive DIY subs for some years as a stereo pair. But even in large (30 foot) listening rooms the positioning was rather critical. They always sounded best when each was placed very close to its matching stereo speaker. But a few inches change in position made a large difference to sound quality. Thouh the rather high 120Hz acoustic crossover to Linn Kans may have been partly responsible for this positioning sensitivity.

    Seperated subwoofers have troughs (cancellations) and peaks(reinforcements) due to phase effects. Even when the subs are perfectly in phase. The long (sound) wavelengths involved cannot all be in phase at all frequencies at the listening seat. Since each wave is reflected from the 4 walls and floor/ceiling boundaries. These reflected waves will sometimes reinforce and sometimes cancel.

    The smaller the room the easier it is to pressurise. But conversely the more difficult it is to avoid clearly audible peaks. Since the smaller the seperation between room boundaries the higher the frequencies of the standing waves between parallel surfaces.

    All of which means that in purely practical terms:
    You should just try anything you fancy and see what works for you. :)

    http://www.mcsquared.com/modecalc.htm


    Nimby
     

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