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Thread: Sound question for all you sound gurus

  1. #1
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    Default Sound question for all you sound gurus

    Here's an odd thing I thought of, but only vaguely understanding the physics of sound, I was wondering if this would work.

    I have a pair of JBL PRX subs I was thinking of building platforms for with the intention of raising them somewhere between one or two feet off the ground, my thought being that the sound really isn't as good as it could be being so close to the floor down by people's feet. Anyone know what that will do? Will I get more sound, will it alter the acoustics negatively, will it hit people a little harder in the chest, will it not really make a difference?

    Thanks!

  2. #2
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    Raising them more than a quarter wavelength from any boundary will decrease output by 3db as they will fail to couple with the floor. You effectively get free amplitude by placing against a boundary as you get a mirror image effect. If you place against a side wall you'll get another 3db 'free' too
    If you want to increase kick try playing with crossover frequencies or get an active crossover if you haven't already get one
    Last edited by norty303; 07-31-2011 at 07:52.
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  3. #3
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    ^^^^ what he said

    plus it does not matter if its aimed at their feet because LF is not directional

    hell its barely sound... you feel it more than you hear it

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    " 15 characters"
    Last edited by Laser Wizardry; 11-13-2015 at 11:59.

  5. #5
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    I sort of had the idea that the reflectivity was against me, or at least not doing anything for me. Thanks for setting me straight on that.

    I have a Driverack PA as my crossover, which is I believe is not active, and I've spent hours just playing around to get the best sound possible out of my rig at different crossover and EQ settings. I've had awesome advice in the area of EQ'ing and I've gotten the system to a really high level of efficiency so far, but I'm always looking to get more out of it.

  6. #6
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    Karl, out of curiosity, why does setting the subs to different crossover thresholds work that way? And I've seen kids crawl into subs, too. Never understood that, but they told me it was to get some sleep.

    Also, I was looking at getting an additional pair of JBL subs, the PRX 618 XLF model, which bottoms out at 30hz. Seems like it's not worth it and for the price, I can almost get three of the standard 618's. What do you think?

  7. #7
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    As it is, I am sloping down from 50 to 40 hz pretty drastically and still feel a lot of bass, which is why I ask about the XLF's.

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    " 15 characters"
    Last edited by Laser Wizardry; 11-13-2015 at 11:59.

  9. #9
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    Let me clarify. I'm not asking if the JBL's, in particular, are better. What I'm asking is if it's worth spending the extra cash on a sub that can hit 30hz as it seems most of what we want is about 45hz or more. Am I getting more rumble and that "bass slap to the chest?" I'm gathering I won't. Like you said, it's personal. I like pushing up 80hz for punchy bass, but I'd def like more deep end out of my system than I have. Maybe I'm just at the limit of what two subs can physically do as opposed to what I want them to do.

  10. #10
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    When I was in school, Full Sail University, one of my first classes was Intro to Medi Arts; it was said low frequencies sounds can cause the human body release small amounts of adrenalin. Not sure if it is true but I do love me some loud, low, bass...
    Love, peace, and grease,

    allthat... aka: aaron@pangolin

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