85L ported shiva with 4" port?

Discussion in 'Home Theater Projects' started by Bob Kavanaugh, Feb 3, 2004.

  1. Bob Kavanaugh

    Bob Kavanaugh Second Unit

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    OK, the 85L ported shiva on Adire's website calls for a 3" flared port cut to 8 3/8 inches. I just got a 4" port by mistake here (sorry Brian, not trying to call you out, just wanted people to know why I didn't just get the 3" one to begin with. I'm cool with our deal 100%).

    Due to the flared ends I can't simply calculate what length I need to trim the 4" port to, to achieve the same tune of 20hz. I am totally lspcad illiterate.

    Anyone?
     
  2. perry web

    perry web Stunt Coordinator

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    i got 25.43" in unibox but I do not know what i am doing.
    i hope someone gives you an answer so I can check myself. want to make sure I am using it right before i design my sub.
     
  3. Bob Kavanaugh

    Bob Kavanaugh Second Unit

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    That's quite a long port. Have you considered Adire's suggested applications? Could save you some time designing, unless you like that sort of thing.
     
  4. Dennis Gardner

    Dennis Gardner Stunt Coordinator

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    WinISD says 25.44 inches
     
  5. Bob Kavanaugh

    Bob Kavanaugh Second Unit

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    Thank you

    What would a 10 inch center get me?
     
  6. Dennis Gardner

    Dennis Gardner Stunt Coordinator

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    The 10 inch center will tune your 85L box to around 27hz.
    To get the 20hz tune you would need a box of 155L. A lot of difference for a $15 part that came out wrong.

    Here is the port length calculator for your port from Precision Sound Products. It will get you to the exact total port length you need. Remember that your 85L= 3 cubic ft.



    PSP Inc. Calculator

    Hope this helps you decide how to go about your project,

    Dennis
     
  7. Bob Kavanaugh

    Bob Kavanaugh Second Unit

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    I'm actually using an original SVS driver, but I followed the Adire alignment for the shiva since they are supposed to model similarly.

    So here's what I've got... An 85L cabinet with a 4" flared port with a 10" center length, a PE 250W amp, and the original SVS driver in a box designed to look just like the SVS PB1. Add to that 40 oz of polyfil to account for the smallish box. I have yet to apply the truck bed finish, but I'll post pics when I'm done. All of this is being built at cost for a friend. Only $240. Pretty sweet deal I think.

    The thing absolutely pounds, I can't turn the amp up past 1/4 or the whole house shakes. Using Avia, at 22hz I can barely hear it, but the house sure can feel it.

    Thanks for the help guys. I'll learn that software one day.
     
  8. ColinM

    ColinM Cinematographer

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    I used the SVS in an 88l box (went for the design spec, but this is where it ended up). My 3" flared port is 8.75" center length. Great sub.

    I wonder if the specs for the SAE1204 would be closer...
     
  9. Dennis Gardner

    Dennis Gardner Stunt Coordinator

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    Bob,

    The lack of output @ 22 hz is about right for the tuning around 27 hz. You will definately enjoy solid bass that should rock your house with what you have built. Enjoy!
    Should be great for both music and movies.

    If you get an urge to hear some really deep stuff, throw together a 140-150L box with a 19 inch long 4 incher. I have 2 in my setup and I am solid to nearly 13hz. I don't know if 1 would do it for me, but feeling it this low on explosions on action DVDs makes it worth the effort. I wouldn't normally have been able to build a 10 cubic foot box, in room, but my old hide-a-bed 3 cushion couch was precisely the size for the project so it is perfectly hidden and acts like tactile transducers for those seated.
    Definately better for movies than for music though made that low.

    Enjoy your new toy, and never stop tweaking!

    Dennis
     

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