Tempest too big, please help me get to 20hz

Discussion in 'Home Theater Projects' started by DustinF, May 11, 2004.

  1. DustinF

    DustinF Agent

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    I'm trying to LspCAD to design a box and I'm not sure if I'm doing it right.

    I have a 12.5'x12.5' room with a sliding door to the rear closet that is 2'x4' (Sub could go in closet, but doesn't have to.)

    I've put in the following in LspCAD

    The Adire Alignment looks good in it, but I can't build a sub that big for this small of room. WAF. Such a waste as I already have a Tempest.

    I've put in a ported 97l Shiva and it looks good. Not as loud as the tempest but over 100l smaller and I never play really loud anyway.

    A 122l sealed tempest looks like it rolls off too early and I'll miss some of the lower bass. This is the max size I could go.

    This will 90%ht/10% music.

    Can anyone try plugging in my room dimensions and tell me if my findings are correct. Or give any suggestions. I'd like to stick with Adire as they have had great customer service, and they are somewhat close to me.

    Thank you.
     
  2. Scott Simonian

    Scott Simonian Screenwriter

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  3. Mike SJ

    Mike SJ Supporting Actor

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  4. John Wes

    John Wes Stunt Coordinator

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    An IB would be the ticket.. Out of sight, out of mind!
     
  5. DustinF

    DustinF Agent

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    Scott- That looks great! Do you know what one of these sound like? I don't want it to be too boomy.

    The eztube with 12" Shiva from creative sound solutions is looking really good right now for only $300.

    About the same as if I bought a another 12" with 15" passive radiator.

    Mike & John- It looks like I'll have to sell the Tempest. IB would be very, very hard because it's near impossible to get to the end of the attic in my house where the room is located. The room is upstairs in the corner, so there's no adjoining rooms to use either.
     
  6. Mitch N

    Mitch N Stunt Coordinator

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    IB is one way to do it. But have you considered an Isobaric? You'll need more power, but you could effectively halve the volume needed for an enclosure.

    Other then that, I think you should build a sample box with no bracing or very little bracing and build it using particle board. This way it's a cheap experiment to see if the room gain will help out on the low notes you think you'll be missing.
     
  7. Scott Simonian

    Scott Simonian Screenwriter

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    This is indeed a good strategy for reducing cabinet volume. The downside is that you will have to use two drivers for every one. Then you also need to double to power. After this, you end up with the same sensitivty as one but in half the size.

    Trade-offs here. Trade-offs there. That is D-I-Y.

    As for the Adire DPL12 with the PR, uh, nah. I doubt it seriously that it would be considered "boomy". I myself have never heard one. Im sure many people here and one other boards have.

    Good luck.
     
  8. AjayM

    AjayM Screenwriter

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    Sealed Tempest in say around 100-120l should get you in-room response easily into the 20's, and with a little BFD help you should be able to go flat to 20Hz and still have a decent amount of SPL capability left over.

    I have a 170l sealed Tempest and in my room it's flat to around 23-24Hz. When I had the same sub in a different room and corner loaded it was flat even a tad lower.

    Andrew
    Room gain is your friend
     
  9. DustinF

    DustinF Agent

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    I'll try the larger sealed first and hope for the best.
    My current 67l sealed dropped like a rock and couldn't hear anything below 30hz. Which is exactely what showed in LspCAD when I put it in. The 120l doesn't look a whole lot better, but real world experience is always different.
     
  10. Jason Dalton

    Jason Dalton Stunt Coordinator

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    You should get some pretty solid room gain in a 12.5x12.5 room. Positioning is going to be key, you might have some pretty nasty nulls because of you're room dimensions.

    I'd try it with a little EQ, I wouldn't be surprised if you could get it flat into the low 20's.
     
  11. DustinF

    DustinF Agent

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    Just got done building a 122l sealed box.
    Huge improvement over the 67l box! I wasn't expecting this much difference. I haven't taken measurements yet, but it exceeded my expectations.

    I moved the box around to every location in the room. About 2ft increments until I found the right place.

    Now the big problem. It's too big, even at only 122l. Looks like I'll still need to get a 12" driver, as the cost of buying another 15" right now is too much. (I'll need to sell the 15.)

    The idea of making it a coffee table sub won't work as that location turned out to be the worst.
     
  12. Mike SJ

    Mike SJ Supporting Actor

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  13. GrahamT

    GrahamT Supporting Actor

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    "why not get another driver and go isobarik? (for Rory Seriously"

    Oh man, I do not want to be around when Rory sees that[​IMG]
     
  14. Rory Buszka

    Rory Buszka Supporting Actor

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  15. minhG

    minhG Stunt Coordinator

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    122L is till too big? my math is off prolly a little off but isn't that a box around 20" cube? how much smaller do you have to get?
     
  16. Mike SJ

    Mike SJ Supporting Actor

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  17. DustinF

    DustinF Agent

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    I built the 122L to really test if it would make much of a difference. It did, but the placement needs to be towards the corner of the room (it sounds best there) and the 22" of space it takes up is just a little too much.. I would have to move my right speaker in, which won't work because it would block part of my screen.
    I was hoping when I built it I could put it in the closet, but this killed a lot of the sound.

    So now I'm thinking I could sell the Tempest and get a Shiva and put it in an 85L ported box. Or a different driver for an even smaller box.

    I just don't have the money to do another Tempest right now. Maybe I can find a used one cheap. I really can't go beyond 17" cube. (I can go a little higher, but no more width or depth.

    In case anyone was wondering, the home theater used to be in a much larger room, hence the Tempest. But now has been moved to the spare bedroom.
     
  18. minhG

    minhG Stunt Coordinator

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    well a 85L shiva is 19x19x20 (per adire's configuration), i'm guessing you'd change those dimensions some to make it fit?

    You're not going to get as good a response from that box as the tempest. that has the least output of all the shiva boxes, its good for music but i'm not sure it will get you what you want.

    you also have to sell the tempest to buy a shiva--which doesn't seem to make money sense to me.

    i'm not trying to bust you, just trying to make sense of it. you seem to be making some contradicting statements.

    if you can't do anything more then 17" cube, i'd go DPL12+PR15, but you said that's out due to budget...
     
  19. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    How about a 12 dB/oct highpass equalization ("Linkwitz Transform", Biquad)

    http://www.linkwitzlab.com/filters.htm#9

    Do the homework and design a simple L-T, and then make your small sealed box subwoofer go deeper than normal. [​IMG]

    (I hope that's right.. heh, cause I never tried one b/c space was never a problem with me as I have Dual 214L tempests tuned to 15.4hz)
     
  20. Dennis Gardner

    Dennis Gardner Stunt Coordinator

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    Dustin,

    Maybe you should try what I did for WAF. A 285 litre Dual Shiva couch! I replaced the hide-a-bed with near 10 cu. ft. of vented EBS tuned to 17hz.

    I can't seem to get her to sit anywhere else but on the couch now![​IMG]

    Dennis
     

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