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1.5 cu. ft box. 10" sub. bracing??

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  • 1.5 cu. ft box. 10" sub. bracing??

    would like some recomendations on bracing for a 1.5 cu. ft sealed box (13.5"wide x 19.5"tall x 13.5"deep) 3/4" mdf. will be home for one 10" sub. box will be solid mounted, screwed down, on the bottom and back.

    i was first thinking of no brace.
    then was thinking of a single vertical 1" dowel.
    then thinking maybe a vertical and horizontal 1" dowel.
    then why not use the extra 3/4" mdf and make a diagonal X (2"ish wide)
    or 3/4" mdf horizontal and vertical + (2"ish wide)

    so as you can read my A.D.D has kicked in and now i am typing, and not making sawdust.

    please, someone, anyone, smack me in the side of the melon and suggest which brace to use/make... feed me ideas.

    thanx all

    i know it has been covered a zillion times, but while i am here. stuffing? fiberglass insulation? cheap pillows? egg crate with cheap pillows? so days i just can't make up my own mind...
    THOMAS BROWN aka "STINKY"

    I've got an idea - an idea so smart that my head would explode if I even began to know what I'm talking about. - Peter Griffin

    I DON'T CARE WHAT KIND OF MUSIC YOU LISTEN TO, OR LIKE.
    SHUT UP, PUT DOWN THE WALLS OF PRETENSION FOR 1 SECOND AND JUST LISTEN TO THE SONGS
    - SCOTT IAN

  • #2
    Re: 1.5 cu. ft box. 10" sub. bracing??

    Originally posted by Thomas Brown View Post
    would like some recomendations on bracing for a 1.5 cu. ft sealed box (13.5"wide x 19.5"tall x 13.5"deep) 3/4" mdf. will be home for one 10" sub. box will be solid mounted, screwed down, on the bottom and back.

    i was first thinking of no brace.
    then was thinking of a single vertical 1" dowel.
    then thinking maybe a vertical and horizontal 1" dowel.
    then why not use the extra 3/4" mdf and make a diagonal X (2"ish wide)
    or 3/4" mdf horizontal and vertical + (2"ish wide)

    so as you can read my A.D.D has kicked in and now i am typing, and not making sawdust.

    please, someone, anyone, smack me in the side of the melon and suggest which brace to use/make... feed me ideas.

    thanx all

    i know it has been covered a zillion times, but while i am here. stuffing? fiberglass insulation? cheap pillows? egg crate with cheap pillows? so days i just can't make up my own mind...
    Keep it simple. The dowels will probably be more than enough. If this is for sub use, that should make for plenty of box stiffness. Otherwise, a couple of window braces cut from the same MDF would work nicely. If you're really worried about it, double up all the walls of the enclosure, make it 1.5" thick.
    R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
    Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

    95% of Climate Models Agree: The Observations Must be Wrong
    "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

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    • #3
      Re: 1.5 cu. ft box. 10" sub. bracing??

      for stuffing if sealed use pillow stuffing or fiberglass.

      Comment


      • #4
        Re: 1.5 cu. ft box. 10" sub. bracing??

        I would use 2 window braces... 1 front to back, 1 side to side. On the front to back brace, cut out space for the woofer magnet. THe bracing wouldn't need to be incredibly thick to do the job. Something like 1/2" oak ply should do it.

        Comment


        • #5
          Re: 1.5 cu. ft box. 10" sub. bracing??

          This is an interesting conversation. I'm with the other posters in feeling sure that the dowels will be strong, but coming from the school of over engineering, here's how I would have done it. You know that little strip of wood that you put underneath the lip of a wooden shelf brace in order to make it able to carry weight? I would have put one down the middle of every surface except the one that the subwoofer resides on.

          Now that I think on it, however, I think I like the dowel idea better, as it's easier. So for that you use two dowels, one up down, one left right, and for the surface on the far side of the sub, you do a reinforcing strip, like I said. Or, if you prefer to make a box that your Ford F150 can rest a wheel on, do it the way I originally was thinking. :-)

          I think we're mutually reinforcing our ADD, though. LOL.

          Joe.
          New to speaker design? Click here.

          Comment


          • #6
            Re: 1.5 cu. ft box. 10" sub. bracing??

            Here's how I'm going to brace an upcoming sub that I'm building... 12" Dayton Ref in a 1.8 cubic foot sealed box.

            Note how with 3 simple pieces of 1/2" mdf all 6 walls are supported... the pieces are also parallel to the direction of the woofer, so they won't reflect the sound back...

            Comment


            • #7
              Re: 1.5 cu. ft box. 10" sub. bracing??

              Dowels - worked fine for my 1200 watt sealed subs

              Comment


              • #8
                Re: 1.5 cu. ft box. 10" sub. bracing??

                What I don't like about dowels is that it's very tricky to support the front and rear walls... everyone ignores bracing of the baffle, which probably sees the most vibration...

                Hence the method I just posted above.

                Comment


                • #9
                  Re: 1.5 cu. ft box. 10" sub. bracing??

                  Originally posted by lunchmoney View Post
                  What I don't like about dowels is that it's very tricky to support the front and rear walls... everyone ignores bracing of the baffle, which probably sees the most vibration...

                  Hence the method I just posted above.
                  Running a dowel underneath each woofer mounting hole would take care of the baffle and back wall.
                  R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
                  Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

                  95% of Climate Models Agree: The Observations Must be Wrong
                  "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

                  Comment


                  • #10
                    Re: 1.5 cu. ft box. 10" sub. bracing??

                    Wouldn't a window pane actually break the baffle into separate sized baffles in terms of its resonance properties? I can't see a dowel doing the same thing.

                    Comment


                    • #11
                      Re: 1.5 cu. ft box. 10" sub. bracing??

                      Originally posted by brianpowers27 View Post
                      Wouldn't a window pane actually break the baffle into separate sized baffles in terms of its resonance properties? I can't see a dowel doing the same thing.
                      The connection from front to rear wall basically doubles the stiffness of the front baffle. And for sub frequencies, where pressure modes dominate over standing waves, having the extra tensional stiffness between opposing walls will drastically reduce the first bending mode of the panel.
                      R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
                      Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

                      95% of Climate Models Agree: The Observations Must be Wrong
                      "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

                      Comment


                      • #12
                        Re: 1.5 cu. ft box. 10" sub. bracing??

                        Originally posted by lunchmoney View Post
                        What I don't like about dowels is that it's very tricky to support the front and rear walls... everyone ignores bracing of the baffle, which probably sees the most vibration...

                        Hence the method I just posted above.
                        Or make your baffles 2 1/4 inches thick like me

                        Comment


                        • #13
                          Re: 1.5 cu. ft box. 10" sub. bracing??

                          I still say my approach wins

                          Very easy to do, and supports all 6 walls very well, right smack in the middle of the panels where they need support the most.

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                          • #14
                            Re: 1.5 cu. ft box. 10" sub. bracing??

                            When I get around to building my 12" sub, I'll brace it like John (Zaph) Krutke's sub.

                            (picture is John's from the Archive section of his web site)...



                            He mentions the principle behind this kind of bracing in his writeup. He also states that it's good only for symmetrical cabinets.
                            Bill Schneider
                            -+-+-+-+-
                            www.afterness.com/audio

                            Comment


                            • #15
                              Re: 1.5 cu. ft box. 10" sub. bracing??

                              Originally posted by lunchmoney View Post
                              Here's how I'm going to brace an upcoming sub that I'm building... 12" Dayton Ref in a 1.8 cubic foot sealed box.

                              Note how with 3 simple pieces of 1/2" mdf all 6 walls are supported... the pieces are also parallel to the direction of the woofer, so they won't reflect the sound back...

                              This method is the only way to go.... Nice drawing by the way...
                              Mark


                              http://www.diy-ny.com

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