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Sub Phase setting.

Discussion in 'Subwoofers' started by pwiles1968, Oct 26, 2003.

  1. pwiles1968

    pwiles1968
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    Can any one explain in simple terms what the phase setting on the sub does to the sound in the room when combined with the other speakers?

    If I put a sub with my main speakers opposite my seat could I set the phase such that the sub would cancel out some of the peaks I was getting from my main speakers, or would I always get a summing of the outputs of all speaker's and even larger standing waves.
     
  2. Crustyloafer

    Crustyloafer
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    In general you should set the phase control to 0 if you have a forward firing sub in line with your main speakers, 90 if it is a downward firing sub and 180 if it is forward firing but faced rearwards.
     
  3. dunkyboy

    dunkyboy
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    That's a good starting point, but to get the best setting you WILL have to experiment (unless you're really lucky! ;) ) Just try different settings until you get the most even response.

    Dunc
     
  4. pwiles1968

    pwiles1968
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    Does this mean you can alter the room response by altering the phase?
     
  5. dunkyboy

    dunkyboy
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    Yeah, and a hell of a lot too! Your main speakers bass will overlap with the sub's at certain frequencies. If these are in phase all will be well, but the fact that the sub is usually positioned off-axis from the speakers (and the fact that getting them exactly on axis is damn near impossible) means they'll be out of phase to one degree or another. This leads to strange and nasty cancellation effects that can have a HOOGE effect on the resulting sound. Incorrect phase settings can REALLY suck the bass out of a sub.

    Cheers,

    Dunc
     
  6. pwiles1968

    pwiles1968
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    So if I got it right I could cancel out my 35Hz Room Peak?
     
  7. dunkyboy

    dunkyboy
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    Umm, yeah, but you'd probably end up cancelling out everything else too..... It's difficult if not impossible to get phase to work for you like that... :(
     
  8. Reiner

    Reiner
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    Sorry, but that's the most absurd explanation I have ever heard regarding this.
    If it would depend on the type of sub they would just hard-wire it or provide a switch for facing into the room or to the rear.

    The only correct statement I see is that the phase should be set to 0 degree if the sub sits between the fronts as the signals are then aligned / exactly in sync.

    If the sub is placed anywhere else in the room you have to adjust it carefully so it sounds best, i.e. that it will be in sync with the fronts. Use some bass-heavy music while running the fronts as LARGE and sending the bass to fronts and sub to determine the correct setting.
    If you only have a 0/180 degree switch your options are somewhat limited.
     
  9. pwiles1968

    pwiles1968
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    I am looking at a BK XLS200 which has variable 0 – 180 I am confident I can align the phase with the fronts I have plenty of test material an like to tinker, I am still a little hesitant about adding a sub to my system as I already have a room peak at 35hz, it is not overpowering and does not interfere with my music listening at the moment, but it may become so If I add a sub.

    Unfortunately in source direct mode my Marantz defaults to sub on and speakers Large so I cannot rely on the amp to x-over.
     

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