AVIA LFE sweep / Crossover gap

Discussion in 'Archived Threads 2001-2004' started by Willem Vos, Feb 13, 2003.

  1. Willem Vos

    Willem Vos Stunt Coordinator

    Nov 14, 2000
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    The Left-Front to sub 200-20Hz AVIA sweep gives me a gap just around 80Hz (with the crossover at 80) setting the crossover to 100 or 120 has no effect on the location of the gap, which leads me to believe that it's not phase related
    (but I tried flipping the phase switch anyway, and it didn't help)

    When I ran the LFE 100-20hz sweep again, the subwoofer has a steady -25dB gap until 65dB, after which the response is flat (but +25dB higher) thanks to the BFD.
    I then set the crossover to 120, so the nearly the full bandwith of the LFE channel should be used by the sub, right? Nope, no change...
    The mains are not making any sound during the LFE sweep, so no cancellations are possible.
    I can't be having a room-gap from 120 to 65Hz, can I?

    If so, how do I go about solving it? Do I have to find another spot for the sub?
  2. Zack_R

    Zack_R Stunt Coordinator

    Nov 4, 2002
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    I know you are concerned about your LFE sweep but give the Avia test I talk about below to see if you can fix your 80 hz cancellation problems.

    I used the avia sub set-up calibration to fix my cancellation problem. If you have Avia play the left speaker and then record the first 2 phase burst for the sub to get an average. Then skip to the right speaker track and record the same two phase burst through the sub. When I did this I got a much lower db response from my right speaker to sub output than my left speaker to sub output. Not only were the db readings lower but it was very audiblly noticeable. I reversed the phase and like magic both sides now had near identical output responses.

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