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Choti Surrounds with 3D Printed/Sand-filled enclosures

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  • Choti Surrounds with 3D Printed/Sand-filled enclosures

    Hey Tech Talk,

    Long time no build thread. Trying something new here, thanks for checking it out...

    So for a while now I've been wanting to build surround speakers for my home theater. They need to be small, wall-mounted, and toed-in quite a bit since the couch is only a few inches from the rear wall. They'll be crossed to a sub at 90hz.

    After researching a number of really nice DIY "micro monitors" out there, I decided on the Choti HT Surrounds, a 1.7 liter vented enclosure using the Dayton RS100-4 and Dayton ND16FA . Big thanks to Navy Guy for sharing his design. See here for his original build thread:

    http://techtalk.parts-express.com/fo...0-4-and-nd16fa

    While the enclosures I've designed are obviously a big departure from the traditional mdf box Navy Guy used, the internal volume and port dimensions are the same. Hopefully I don't screw it up in some other way, no doubt Tech Talk will let me know

    For a number of reasons, not the least of which is a big new resin printer in my possession, I decided to 3D-print the enclosures, with hollow outer walls that I'm going to fill with sand. Not sure if these qualify as "decoupled walls", as there are quite a few very strong ribs tying them together.... but perhaps some benefit will occur over a typical plastic speaker. That is the hope anyways.

    The sand will be filled to within 1/8" of the top, and then I'll cap it off with epoxy. In order to make sure the sand is well packed, I'm going to somehow vibrate the enclosure as the sand is being poured.... I'm thinking I might hang the enclosure from a rope and tap it with a mallet as I'm filling it with sand. and then tamp it down as I go. This will no doubt take some experimentation....

    The insides will be lined with 1/2" sonic barrier.

    First are some screenshots from Solidworks. Note that I'm showing some cross-sections here so show what's going on inside better....
















    And now for the prints. Phrozen Transform Sonic printer with Epax Hard Resin. Print time 22 hours.






    Form does not follow function
    Form is simultaneous to function

  • #2




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    Form is simultaneous to function

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    • #3
      Drivers and crossover parts are on order, will post more soon.
      Form does not follow function
      Form is simultaneous to function

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      • #4
        Nice! How much do they weigh?

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        • #5
          Originally posted by zx82net View Post
          Nice! How much do they weigh?
          Hard to say exactly... the empty enclosures weigh a few pounds; with sand and drivers I'm guessing 12-15 lbs. The three keyholes on the back accept big drywall anchors, so it should be ok.
          Form does not follow function
          Form is simultaneous to function

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          • #6
            That's some CAD skillz right there
            ~Brandon 8O
            Please donate to my Waveguides for CNC and 3D Printing Project!!
            Please donate to my Monster Box Construction Methods Project!!
            DriverVault
            Soma Sonus

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            • #7
              Originally posted by augerpro View Post
              That's some CAD skillz right there
              Thanks. Not that bad actually. No tricky surfacing or anything, just a bit of patience.


              Last edited by lunchmoney; 01-24-2021, 01:28 PM.
              Form does not follow function
              Form is simultaneous to function

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              • #8
                Are you changing the bsc since they will be wall-mounted? Just curious.

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                • #9
                  Very cool! If these are wall mounted what are you doing for terminals? And how does one finish a printed resin? Sand and paint? Wrap in a vinyl or other covering? Leave as is?

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                  • #10
                    Originally posted by dstmbgh View Post
                    Are you changing the bsc since they will be wall-mounted? Just curious.
                    Great question. I wasn't going to change it, as I don't have the skills to do so. I figured I would live with it as is..... How much of a change would this be for the crossover?
                    Form does not follow function
                    Form is simultaneous to function

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                    • #11
                      Originally posted by unclejunebug View Post
                      Very cool! If these are wall mounted what are you doing for terminals? And how does one finish a printed resin? Sand and paint? Wrap in a vinyl or other covering? Leave as is?
                      The terminals will poke out the bottom cover, holes not shown yet. The bottom cover isn't done yet, I will also be adding more stiffening ribs.

                      I'll be veneering them (exact wood TBD). Note the easy-to-veneer shape.
                      Form does not follow function
                      Form is simultaneous to function

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                      • #12
                        Cool project Dan! I hate MDF!
                        Craig

                        The lowest possible F3 box alignment is not always the best alignment.

                        Designing and building speaker projects are like playing with adult Lego Blocks for me.

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                        • #13
                          Those look great! I used the Choti design for a boom box a while ago and thought they sounded really nice!

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                          • #14
                            I received and did some quick cad of the crossover components, thankfully it seems like they will fit just fine....








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                            • #15
                              Originally posted by Jeff F. View Post
                              Those look great! I used the Choti design for a boom box a while ago and thought they sounded really nice!
                              Thanks. That's great to hear.
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