Volume gain from stuffing sealed enclosures?

Discussion in 'Home Theater Projects' started by MichaelAngelo, Apr 1, 2003.

  1. MichaelAngelo

    MichaelAngelo Stunt Coordinator

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    Help please with a n00b question. What kind of increase in apparent volume can I expect from stuffing a sealed enclosure? I'm using the cheap Wal-Mart stuff, poly-fill. One enclosure is 19cuft, I used 15lbs stuffing (.5-1.5 lbs per cu ft, right?). The other enclosure is about 23cuft, and theres about 20lbs of stuffing in it.

    Also,,,

    Does the Vd of a passive radiator get "added" to the Vd of the driver in a PR system?

    Thanks for any help.
    Mike
     
  2. Frank Carter

    Frank Carter Screenwriter

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  3. Joel X

    Joel X Stunt Coordinator

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    It sure would be great if modeling programs took poly-fill into the equation. I guess I am assuming that they don't since I have only used one and its newer alpha version...
     
  4. David Lorenzo

    David Lorenzo Stunt Coordinator

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    Those are some big boxes you got there. What drivers are you using in them?

    I don't understand your question about the Vd of a PR. Could you clarify that a bit more?
     
  5. MichaelAngelo

    MichaelAngelo Stunt Coordinator

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    I see the displacement listed in the specs of various subs (point-to-point xmax x SD). In a sealed enclosure, it displaces x amount of air. In a PR setup, it also displaces x amount of air, but so do the PRs. Does the displacement of the PRs get added to the driver to determine expected SPL? Or does the Vd of the PR only come in at tuning?

    The drivers I'm using are for car audio,2 15" Kicker solobarics (square). Tried to get in on the AV sale, but no luck. 4 PE 250w amps, 1 on each voice coil.

    Pod race [​IMG]
     
  6. Geoff L

    Geoff L Screenwriter

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    Mike
    The larger the encloser the less effect of gaining volume that the drivers sees. With the size boxes you have I don't think you will see that much gain.

    It may help with dampening and back wave problems but unless the drivers are in smaller seperate enclosers inside your one large encloser, I think you will find that you won't gain a whole lot, certainly nothing like you would with boxes under 2.5ft^3. Up to 30 to 35% can be obtained in much smaller enclosers according to Tom N's stuffing measurments.

    Those cabinets are huge to begin with. WOWZER
    Hope all your work pays off for you, as it sounds like allot of labor went into theses.....

    Regards
    Geoff
     
  7. Brian Knauss

    Brian Knauss Stunt Coordinator

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  8. MichaelAngelo

    MichaelAngelo Stunt Coordinator

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    Thanks to everyone for your replies. I think I have my answer to the stuffing question.

    Geoff, one enclosure is an MDF box, with Vd ~23 cuft. The other is a 24" piece of Sonotube,75" long(72" int) with 1.5" plywood endcaps. The sontube "rang" when knocked on, till I stuffed it. That cured the ringing. The MDF box will soon be replaced with a sonotube, as I'm not satisfied with the bracing.

    Besides, I like the square-speaker-in-a-round-box look!
     
  9. Allen Ross

    Allen Ross Supporting Actor

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    okay now i gotta see some pics of that
     
  10. TimForman

    TimForman Supporting Actor

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    I've read where it's possible to encounter standing waves inside 'tubes that are around 6' in length since that's close to the quarter wave length for the 90-100 Hz range and that stuffing can help with that. Any thoughts?
     

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