Will this space be okay for an IB setup ?

Discussion in 'Home Theater Projects' started by Joe Mihok, May 12, 2005.

  1. Joe Mihok

    Joe Mihok Second Unit

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    My wife an I recently bought a house (woohoo [​IMG]) and now I have the option of trying out this thing people call the "Infinity Baffle". I currently have a 15" Tempest in a ported 194 litre enclosure. While I am happy with the Tempest, it's huge and always an eyesore. Also, I'm always wanting to take on new projects and this one seems fairly inexpensive yet should offer good results. Anyways, the plan was to use a crawlspace located right beside my HT. I will take my Tempest driver out of the ported enclosure and use it for the IB. Later on down the road, I plan on buying another Tempest to run duals. Here are pics of the space:

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    The plan is to remove the flimsy door and screw on a sheet of MDF with the drivers and speaker mounted to it facing into the area. It will be done very similar to this:

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    I realize I won't be able to get into the crawlspace again unless I unscrew the MDF but I don't see that as a problem. So, do you think this space will work out ? And will it sound better than my current SBB4 194L Alignment ? And yes, I have a BFD and will flatten out the response.

    Thanks for any input guys!
     
  2. Joe Mihok

    Joe Mihok Second Unit

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    One should also note that the floor to the second level is located on the roof of the crawl space. if I wanted, I could easily make a small vent to join the two areas together. this would then make 1100 square feet of additional space for the enclosure. would this benefit the IB?
     
  3. ThomasW

    ThomasW Cinematographer

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    How many cubic feet are in the storage area?

    That doesn't work. There would need to be a large opening to make 2 spaces function as one.

    If the budget permits you should buy a pair of Avalanche 18"s at the closeout pricing.

    www.ascendantaudio.com
     
  4. Joe Mihok

    Joe Mihok Second Unit

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    The storage area is 152 cubic feet. And if I were to make a vent it would be as large as a regular furnace outlet. Sorry, money is VERY tight. I'm stuck with the Tempest for quite some time so I can't even look at the AV18's.
     
  5. ThomasW

    ThomasW Cinematographer

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    A vent that small is useless.

    The opening between 2 adjacent spaces, needs to be as big as the wall dividing the spaces, for it to effectively add to the area of an IB.

    You might want to wait until the budget allows multiple drivers with higher excursion before going with an IB.

    A single Tempest mounted in an IB will not give you the same 'punch' as your existing sub.
     
  6. Joe Mihok

    Joe Mihok Second Unit

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    okay, so say one day I had anough $$ for dual 18's, would the space suffice ?
     
  7. ThomasW

    ThomasW Cinematographer

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    Depends on the Vas of the drivers.

    All this is explained in the FAQ section of the IB forum
     
  8. Mattak

    Mattak Stunt Coordinator

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    I don't see why you shouldn't try. You could make a new door out of 2 layers of mdf, mount the hinges and latch to it, and seal it with a strip of closed cell foam to test out the idea very easily. I say give it a shot!
     
  9. Matt Bahnson

    Matt Bahnson Auditioning

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    Joe,

    An IB desgin has to be exactly that, an infinite baffle, in order to take full advantage of the design. This is a great idea, but take this into consideration: How many high end or even mid range subwoofers have you encountered that are made of 2x4's and dry wall? Your storage area was designed for storage, not extreme constant vibrations. I predict that you'll have a huge problem with sympathetic vibrations and possibly some serious whistling. Puting a sub in the area is a great idea, but I would build a really good sized box out of some solid 3/4" to 1" MDF and make sure to have a "face plate" or something of that nature that is exactly the size of the door...simply slide the whole box into the storage closet and mesh the "face plate" up with the door frame and you have the LOOK of a storage closet sub, without the sonic drawbacks.

    Just and idea.

    FYI, a 48" by 48" piece of 3/4" MDF is about $37 at Home Depot.
     
  10. Matt:Brunmeier

    Matt:Brunmeier Stunt Coordinator

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    uhh, you can get a 4'x8' sheet of 3/4" MDF for like $22 at Home Depot here.

    you're getting ripped off [​IMG]
     
  11. ThomasW

    ThomasW Cinematographer

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    First by definition an infinite baffle is one where the baffle (not the space behind it) is infinitely large. Having that prevents the front and rear waves from canceling.

    Second, the space behind the baffle does not need to be infinitely large. For optimal performance an area with a volume that's 10 times the sum of the driver's Vas, effectively functions as infinite space as far as a loudspeaker is concerned. But it's actually possible to use a space with a volume as small as 4 times Vas and get acceptable performance.

    Building a 152 cu ft wooden box inside the space isn't necessary. Unlike 'portable' box subs where extraordinary means should be used because of the pressures involved, one can obtain extremely good sound quality with standard home wall construction.
     
  12. HowY

    HowY Extra

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    What it seems everyone is saying is this
    is effectively an enclosed cabinet and
    I would agree, If indeed there can be
    a large effective vent to a MUCH larger
    space an IB may perform there.

    an IB needs at least twice the volume
    behind the driver (infinity) than the
    volume of the space it's filling so
    there is no pressure wave behind the
    cone/driver - Love IB subs!

    Read between the lines - work out the
    VAs & Q's of the space you have and
    build a sub out of that space, port
    if needed make a nice sub area.

    I personally would be quick to make
    that space into rack - equipment
    media space.
     
  13. ThomasW

    ThomasW Cinematographer

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    Nope it doesn't. As I said, 4 times Vas is minimum, and 10 times Vas or greater is optimal.

    Those people doubting my recommendations, are welcome to checkout the link my signature for additional info regarding IB subs.
     

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