Dual Opposed

Discussion in 'Subwoofers' started by fuzz092888, Feb 1, 2013.

  1. fuzz092888 Audioholic Warlord

    fuzz092888
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    I was thinking about doing a dual opposed build with some TC Sounds LMS Ultras. I have no timeline for this, so don't expect a build thread any time soon, but I'm rolling the idea around and I'd like to see if I can get some box plans and maybe even a cut list hammered out with a little help from anyone who cares to. I've never done box plans from scratch before, so I'm on the hunt for some suggestions and advice.

    Now, after seeking advice from TLS Guy, he recommends a box of about 4cu ft. I've been trying to mock something up on sketchup, but admittedly I'm finding I'm pretty terrible at it. I'm sure I'll figure it out eventually, but a little help never hurt :D

    Anywho, if anyone's got the time to help with a sketch up mock up or some advice on dimensions and bracing, I'd appreciate it.

    One last thing, given that this thing will probably be generating some pretty significant force I've been considering getting the pieces CNC cut so I know all the cuts are true and accurate. Although it's kind of hard to figure out how much that's going to cost without a box mockup and some dimensions, which is also why I'm seeking a bit of help.
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  2. j_garcia Audioholic Jedi

    j_garcia
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    True and accurate definitely helps, mostly with appearance and assembly IMO. You will ideally seal the cabinet internally with some sort of material like RTV, and presumably would be using wood glue at the joints as well. So I wouldn't necessarily consider "true" straight cuts a major structural benefit, but they are definitely a benefit to you.

    If you can get someone to provide you rough dimensions and how many and where to place braces, I can CAD it up for you.
    Last edited: Feb 1, 2013
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  3. fuzz092888 Audioholic Warlord

    fuzz092888
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    Thanks J, I was hoping to get some rough dimensions from another dual opposed build over on AVS and then adjust them to the cuft I was shooting for. I got a few dimensions, but I'm missing a few. I'll see if I can figure them out tonight. Thanks for the offer, hopefully I can get those dimensions worked out.
  4. fuzz092888 Audioholic Warlord

    fuzz092888
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    So This is what I've got so far:

    External Dimensions: 29"D X 25" H X 22" W

    Internal Dimensions: 26" X 22" X 19"

    Material thickness 1.5"

    Center brace between drivers: .75" D X 22" H X 19" W

    4 Small braces, meant to span front to back, above and below the driver: .75" D X 12 5/8" H X 19" W

    Kinda like this, the center brace is on the right and the smaller braces are on the left:

    [​IMG]

    Then this is how they fit into the box:

    [​IMG]

    As you can see from the second picture, there are smaller braces on either side of each driver, but I'm not sure what dimensions might be. The pictures show the box I'm going off of, but trying to translate into a smaller enclosure because that one is about 9.5 cubes I think.

    Let me know what other dimensions you need. Thanks again j.
    Last edited: Feb 1, 2013
  5. fuzz092888 Audioholic Warlord

    fuzz092888
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    So the center brace is 12 5/8" from the front and the same distance from the back. Dead center front to back and spans the internal width and height.

    The four smaller braces:

    The bottom of the smaller brace is .99 inches from the bottom and the same goes for the top. The tops of the smaller braces sit tangental to the recessed area in the picture above.

    According to the TC Sounds website the driver cutout is 16.83" in diameter and the wider wider recessed area is 18.52" in diameter. All 4 walls are .75" thick, but doubled up so the drivers will be flush mounted.
  6. TLS Guy Audioholic Overlord

    TLS Guy
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    I have found out your drivers will displace 0.677 cu.ft if you front flush mount them. I already allowed for the damping, so you just have to add the brace volume to 4.7 cu.ft. The total internal volume is going to end up some where north of 5 cu.ft. You really need to brace this and I would use inch mdf, or better two thicknesses of 3/4". I think wall thicknesses of 1.5 inches are very appropriate for this build. The internal forces are going to be something else. You really need to use figure of 8 type bracing, not just 2X4s scattered about. This will be a serious piece of equipment.
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  7. fuzz092888 Audioholic Warlord

    fuzz092888
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    I'm sorry for my ignorance, but what is figure 8 bracing?
  8. Adam Audioholic Jedi

    Adam
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    I bet that Alex is on his way to demonstrate right now. :D
    Adam,
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  9. TLS Guy Audioholic Overlord

    TLS Guy
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    This is the general idea.

    [​IMG]

    The braces need to be fixed to the sides with a dado type construction. A dado can be made with a router and guide, or better a dado blade on a table saw. Loudspeakers are best constructed with dado joints through out and not butt joints. This type of construction also allows you to use pre veneered boards, which makes finishing a lot easier.
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  10. fuzz092888 Audioholic Warlord

    fuzz092888
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    He always gets a bit "handsy" in his "demonstrations" so I doubt I'll actually learn a whole lot :p

    Plus there are always bananas, go figure :confused: :D
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  11. fuzz092888 Audioholic Warlord

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    Hmm, looks like the dimensions are about to go through their 4th iteration tonight. I also have to figure out how to work that into the design because the space is so tight. Thanks for the suggestion, definitely going to look into it.
  12. ahblaza Audioholic General

    ahblaza
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    Alex, that is some serious space and force
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  13. fuzz092888 Audioholic Warlord

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    Hey man, just trying to keep up with you :D
  14. j_garcia Audioholic Jedi

    j_garcia
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    So do you want me to come up with something or wait until you've got the numbers?
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  15. fuzz092888 Audioholic Warlord

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    If it's ok with you, I'd say hold off for now. I'm still playing with the numbers and taking some measurements for placement. Plus now I've got to rejigger things again to account for the thicker bracing. I'll PM you dimensions when I get closer to something resembling a finished product.

    Thanks again for doing this, I really do appreciate it.
  16. fuzz092888 Audioholic Warlord

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    So I'm trying to figure out bracing and in order to fit 1.5in thick bracing I had to increase some of the dimensions. I'm still only coming out to about a cubic foot of bracing, making the box volume right around 5 cu. ft. not counting stuffing. I'm guessing that's ok because in one of your PM's you had said that right around there was the optimal range.
  17. TLS Guy Audioholic Overlord

    TLS Guy
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    I would say you are on target. Don't forget the displacement of the drivers. 0.677 cu.ft.
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  18. Alex2507 Audioholic Overlord

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  19. fuzz092888 Audioholic Warlord

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  20. Alex2507 Audioholic Overlord

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    Awesome !!! :D
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