IB or Ported Dual Shivas

Discussion in 'Home Theater Projects' started by Ben Ven, Feb 17, 2005.

  1. Ben Ven

    Ben Ven Stunt Coordinator

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    I have been running dual Shivas in an IB setup in my basement. I am moving my HT to an upstairs bedroom. I have a closet available and have already made a cutout to mount my dual Shivas. After filling the closet with junk, I worked out a volume of about 1500 L. After modelling on Unibox, it looks like ported is the way to go. However, the port lengths are ridiculously short, like 7-8 cm. Am I going to get proper performance in a ported box with this much volume? Or is IB the way to go? It looks like I can squeeze out a few more dBs between 20-30 Hz in a ported enclosure. Any advice??

    www.boomspeed.com/benven/CompareResponseAdireShiva.gif
     
  2. ThomasW

    ThomasW Cinematographer

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  3. Ben Ven

    Ben Ven Stunt Coordinator

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    I wish I could!! I don't have alot of room up in that part of the attic. The room has cathedral ceilings and I can barely get in there let alone work.
    The closet is big enough, at least according to Unibox, to act as an IB. Not much difference in response between 1000 L and 9999 L.
    My design choices are closet IB or closet ported. I absolutely love the sound of IB downstairs, but is there any advantage to go ported?? Will a ported design work well with the volumes we are talking about?
     
  4. ThomasW

    ThomasW Cinematographer

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  5. stephanX

    stephanX Stunt Coordinator

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    Ported will have more output most likely, and will need more power to get truckin

    Ib will PORBABLY sound cleanest of all, but will have least output and will take the LEAST power(that said it also wont take much to get to max output [​IMG])

    Sealed is a good compromise but will have the LEAST low end(depending on the ported box tuning i guess) and will take a little less power than the ported box(due to recuced excursion at tuning(assuming an appropraite rumble filter is used on the ported box))

    I think a whole closet acting as a ported box would be wicked!
    and a port would be short, as the bigger the box gets, the shorter a port needs to be to get desired tuning.
     
  6. stephanX

    stephanX Stunt Coordinator

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    Ported will have more output most likely, and will need more power to get truckin

    Ib will PORBABLY sound cleanest of all, but will have least output and will take the LEAST power(that said it also wont take much to get to max output [​IMG])

    Sealed is a good compromise but will have the LEAST low end(depending on the ported box tuning i guess) and will take a little less power than the ported box(due to recuced excursion at tuning(assuming an appropraite rumble filter is used on the ported box))

    I think a whole closet acting as a ported box would be wicked!
    and a port would be short, as the bigger the box gets, the shorter a port needs to be to get desired tuning.
     
  7. Ben Ven

    Ben Ven Stunt Coordinator

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    Ported will have more output most likely, and will need more power to get truckin
    --------------------------------------------------------
    Yeah!!

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    Ib will PORBABLY sound cleanest of all, but will have least output and will take the LEAST power(that said it also wont take much to get to max output )
    ----------------------------------------------------------
    Yup!

    --------------------------------------------------------
    Sealed is a good compromise but will have the LEAST low end(depending on the ported box tuning i guess) and will take a little less power than the ported box(due to recuced excursion at tuning(assuming an appropraite rumble filter is used on the ported box))
    ----------------------------------------------------------
    Yup again.

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    I think a whole closet acting as a ported box would be wicked!
    and a port would be short, as the bigger the box gets, the shorter a port needs to be to get desired tuning.
    -----------------------------------------------------------
    I think so too. I decided that ported it's going to be. The port lengths are going to be short, like 3, 4" ports at 2.25" long. Tuning at 18 Hz in a 54 ft^3 box!! Unibox is a wonderful tool!
     
  8. Rich Kraus

    Rich Kraus Stunt Coordinator

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    ok, so you cant work IN the attic... is there enough volume to IB the shivas? i had a similar problem, enough room belly crawl to the location to run wire, but no room to work (it opens up to a larger space so the 10XVAS is no problem).

    result? surface mounting. just cut out a rectangle of drywall between joists, and screwed up a baffle with the drivers already mounted. only problem was holding 50 lbs of drivers and baffle over my head while i connected the speaker leads:

    [​IMG]
     
  9. Ben Ven

    Ben Ven Stunt Coordinator

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    Good work. You hung those yourself without help?? Wow.

    I already thought of that but the wifey said nay. No holes in the ceiling!

    I will try the ported route and if it does not work out well, I can always replace the baffle and run sealed.
     
  10. stephanX

    stephanX Stunt Coordinator

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    only 50lbs of speaker?....pussy

    But yeah nice install you got there! maybe a really thick grill to cover the whole thing?
     
  11. Rich Kraus

    Rich Kraus Stunt Coordinator

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    ben, its important to enphasize the "i wont need a big boxy, ugly, speaker in the room" pitch to soften the IB concept. or do what i have done both times (this is my second IB in as many homes), simply cut the hole and get it finished when she's not home [​IMG] understand this requires some degree of pre planning, especially if you plan to do a grill over the hole to mask things....

    anyway....

    if i had to simply hang them alone it wouldnt have been a probelm, it was holding them up there while attaching the speaker leads that was difficuilt. picture me up on a ladder (the celing is 9'4" in that room) ballencing this mess, basically holding it between my chest and the wall so i had both hands free to opperate the binding posts.

    for this install i dont really need a grill, they are on the celing agenst the front wall of a dedicated theater room, there will be (when funds surface) a stage/procenium/thing that will hide these and the rest of the front speakers from view. (which is a bit of a shame since i think my 281's look pretty good...)

    heres the (not updated [​IMG] ) page for the theater:

    http://www.richkraus.com/ht

    anyway back to your situation. i recomend you get your SO over to the cult picture gallery, let her see some of the finished subs since you already have a no'ish response. let her see how good it can look if a little effort is put forth. some of those installs are completly stealth. you could do one like mine and frame a cloth grill over it and assuming a close color match it would all but disasapear.
    keep in mind that if the celing is drywall, a hole can be un-holed pretty easily....

    if anyone was confused, i say if you can at all possibly do an IB, do the IB.
     

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