what is the Phase switch on my sub

Discussion in 'Archived Threads 2001-2004' started by JamesMartin, Aug 9, 2001.

  1. JamesMartin

    JamesMartin Extra

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    Hi guys, I have a Klipsch KSW-10 subwoofer and I just got my hometheater up and running. I am pretty new to all this and have one small question concerning my sub. On the back it has a "phase" switch labled "0" and "180". what does this mean, do, etc.?
    Thanks
    JamesMartin
     
  2. John Garcia

    John Garcia Executive Producer

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    Putting the switch to 180deg will cause the sub to play 180deg out of phase with respect to your other speakers. It is generally to fine tune to a particular room's acuoustics and fight phase cancellation between the sub and your other speakers.
    Use the sub at 0 for a while, then listen to it 180 out of phase for a while. On my sub, I can hear a distinct difference with it set to 180.
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  3. GarryW

    GarryW Stunt Coordinator

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    I believe the phase switch allows you to coordinate the movement of the subwoofer cone to work in harmony with the woofers on your fronts.
    If the sub is "out of phase" with the fronts, i.e. moving out while the fronts are moving in, this could cause some cancelling out of low frequencies thereby contributing to a poorer sounding low end.
    My Paradigm PW-2200 has a 0° to 180° phase adjustment knob which I have set at 90°. I was told by my dealer to have an assitant turn the knob while I listen and when the low end sounds the loudest, leave it at that setting.
    FWIW, I've never noticed any big change in sound.
     
  4. John Garcia

    John Garcia Executive Producer

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    I have a Yamaha YST-SW500 sub which has a remote control. When I switch phase, the difference is detectable, but not so much that I prefer it one way over the other.
    Paradigm makes a sub control module, but I'm not sure if it is remote controllable. Cambridge Soundworks has a sub control module that does have a remote. I find it to be a very useful feature when tuning the system
     
  5. Jeremy Anderson

    Jeremy Anderson Screenwriter

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    A phase problem will rear its ugly head in the crossover range, where your sub and your speakers are playing at the same time. In other words, if your system is crossed over at 80hz and your sub is out of phase with your speakers, a bass frequency sweep will quickly show you a large decrease in sound from about 65-95hz because you're cancelling out those frequencies.
    Usually, you can leave this at 0 degrees, which means it is pushing out at the same time as your speakers. However, due to subwoofer placement and room acoustics, your room may reflect that wave in a way that essentially reverses it, which is what causes cancellation (in which event you'd use 180 degrees). I strongly recommend picking up a copy of The Avia Guide to Home Theater on DVD, which has both noise and warble tests to determine optimal placement, phase and level of your subwoofer.
     

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