Infinite baffle edu?

Discussion in 'OT Technology' started by squid, Apr 15, 2008.

  1. squid

    squid braap

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    Does anyone have a good guide to building an infinite baffle sub for a home theater? I have a little crawlspace above my theater that I think should be perfect for this kind of application.
     
  2. ssabripo

    ssabripo Banned

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  3. squid

    squid braap

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    This sounds really complex and more than someone who knows nothing (me) can handle reliably. I think it's worth it to hire an AV guy to do it. The situation is kind of perfect with the crawl space right above the theater, so I think it's worth it to get a little work done for it. Even if I am cheap :mamoru:
     
  4. GammaRadiation

    GammaRadiation Active Member

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    IB is rather simple. Seperate the front waves from the back infinitely. If cosmetics arent important it is as easy as building a strong, well braced baffle and cutting the holes out.
     
  5. Freonthewhite

    Freonthewhite FrEoN OT Supporter

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    sounds kinda crazy, how much better could it possibly be than a regular subwoofer? i'm so bad at this that i'm assuming that this is just for bass
     
  6. GammaRadiation

    GammaRadiation Active Member

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    No worries about cancelation issues.
    The cone is controlled strictly by the driver's suspension.
    No worries about a poor transient response.
    No worries about group delay problems.

    It is the perfect sound quality alignment.
     
  7. squid

    squid braap

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    Hm. I'm getting conflicting reports here. I have an A/V guy that does all kinds of cool shiz, and when I brought this up to him he said it was "sloppy". He didn't elaborate but suggested I would need a box anyways. I'm confused on the whole issue, but he said he was sending me info, we'll see.

    In any case, I'm not cutting a hole in my roof, and he doesn't seem enthused with the idea either, so ...
     
  8. eighteen_psi

    eighteen_psi Active Member

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    Long story short: COMPLETE separation of front/back driver output.
     
  9. BoomBoomBoy

    BoomBoomBoy Guest



    :bigthumb::bigthumb::bigthumb::bigthumb::bigthumb:
     
  10. Doc Brown

    Doc Brown Don't make me make you my hobby

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    It's not nearly as complicated as it sounds.

    Just pay attention to the qts number in the speakers specs.

    A good woofer for an IB alignment is going to have a qts of around .6 or higher.

    The only problem I would have with the two subs ssabripo posted is that the voice coils have very low ohms ratings.

    Those take extremely beefy amplifiers to handle such loads.

    Your basic Sony/Yamaha style amp is going to have a meltdown if it tries to push a load that low.

    So if you go with something like that, be sure the amp is rated for seriously low ohms at high output.

    And for home theater, you start looking at pro sound setups with amps like Crown, Crest, or extremely highend amps like McIntosh, Krell, etc.
     
  11. GammaRadiation

    GammaRadiation Active Member

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    A 2kw Crown one a pair of 18's with good throw would be perfect for a decent sized HT.
     
  12. XR250rdr

    XR250rdr OT Supporter

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    Or just run 2 of them.
     
  13. Doc Brown

    Doc Brown Don't make me make you my hobby

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    Something tells me thread starter is not looking to use a pair of woofers with a vas of 10-13 cf vas each.
     
  14. squid

    squid braap

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    thread starter doesn't even know what that means :mamoru:
     
  15. XR250rdr

    XR250rdr OT Supporter

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    Using a crawl space that isnt too much of an issue. But it appears he isnt going to cut into that anyway.
     
  16. ssabripo

    ssabripo Banned

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    we have "experts" in IB's all of a sudden?? :ugh:


    :rofl:

    only in OT, I swear
     
  17. squid

    squid braap

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    I'm not objecting to it being done, I just don't want to start cutting myself. I'm still waiting on my AV guy to get back to me with some real proposals. If nothing else, it'd be nice to not have more crap on the floor.
     
  18. XR250rdr

    XR250rdr OT Supporter

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    I see. It sounded like after talking to your AV guy you didnt want to cut into it at all. :o

    You've been around long enough you should have known that already ;)
     
  19. Doc Brown

    Doc Brown Don't make me make you my hobby

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    Yeah you're right, but I was thinking that these being mono subs that it would
    require 4 of them total, in order to get the ohms up enough for a regular amp.

    But yeah, I kind of blew right over the crawl space reference.

    Mainly I was thinking about the IB issue. Pretty much any high qts, high compliance woofer in a sealed box with a low Q, will be an IB alignment.
    There's supposed to be equal Fc and Fs also, but it's more about the system q.
    It doesn't really hurt low end performance to go with a larger box, but I would imagine that you could measure a difference in transient response as the volume gets larger, due to a less "springy" air load on the woofer.
     
  20. ssabripo

    ssabripo Banned

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    IB anyone?

    latest one I helped with....

    [​IMG]
    [​IMG]
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    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]

    and of course, FLAT to 10hz!
    [​IMG]
     
  21. Arc

    Arc New Member

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    I am putting a pair of those in my car. Gonna have to cut the trunk somewhere though.

    If your A/V guy said IB is sloppy...he probably hasn't used it and is talking out his ass. Sorry.
     
  22. Doc Brown

    Doc Brown Don't make me make you my hobby

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    ssabripo, you know you're insane, right?


    :eek3:


    Edit*

    Or I should say, the guy that you helped put those together for.

    What size room did those go into?





    .
     
    Last edited: Apr 24, 2008
  23. GammaRadiation

    GammaRadiation Active Member

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  24. squid

    squid braap

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    AV guy said you need a box for the sub to react against. AV guy said that without that, you can get tons of sloppy bass, but if you want something tight and sonically accurate, you need something for the sub to react against. Or something.

    AV guy said he could get me this for stupid cheap:
    http://www.earthquakesound.com/ff12.htm

    That's easy so I think I'm just gonna do that :lmao:

    Thanks for the advice.
     
  25. Doc Brown

    Doc Brown Don't make me make you my hobby

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    If you're going to go with a pre-made sub you should definitely get some opinions here first. I can just about guarantee you that one of the guys will have a better deal to point you to than that Earthquake sub.
     

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