Adding a board under a sub on carpet

Discussion in 'Speakers' started by Chase, Sep 28, 2004.

  1. Chase

    Chase Agent

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    I have the JBL PB-12. A 12 inch downward fireing 250 watt driven sub. However I have noticed it can't repouduce frequinces in the 85-150hz range as strong as most subs do.

    If I put a wood board under it over the carpet for it to sit on would this help out any?
     
  2. Lee Carbray

    Lee Carbray Second Unit

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    It is hit or miss at best. There is no telling what if any diff it would make or in what region.

    Have you plotted the responce of you sub? Where is your crossover? Possibly you have a phase issue.

    In the 85-150HZ if you have a typical 80Hz crossover your mains are having as much impact on the sound as you sub. The subs you have heard with better impact in this range, did you hear them in your system or with other speakers?
     
  3. Chase

    Chase Agent

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    My speakers are the same ones I have used on some of my other subs. I have some smallmed size kenwood speakers at the momoent. I have the reciver set to small speakers cause they can't do much in that area. The sub's crossover is set around 120hz
     
  4. paul clipsel

    paul clipsel Stunt Coordinator

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    I have a downfiring subwoofer and I could not measure any difference with a big mat under it or direct on the wood floor. If you have it in the best position you should measure the rooms freq response at the main chair and see whats happening.

    PC
     
  5. Lee Carbray

    Lee Carbray Second Unit

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    With a crossover at 120hz phase could be the problem. Have you tried adjusting the phase on the JBL? The only way to really see if it is lacking in the region you are describing is to plot the output with test tones and an spl meter.

    But if you have some scrap wood give it a go. You may also want to try a patio stone. I have read people having good results with that. Not specifically for your problem but it may help
     

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