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Build Thread: HELIX full range 3D-Printed speakers with 3" Fountek FE85

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  • Build Thread: HELIX full range 3D-Printed speakers with 3" Fountek FE85

    Hello all,

    It's been way too long since I've done a build thread (or built any speakers for that matter).... nice to be back.

    The goal of this build was to create a single-piece 3D-printed vented speaker housing with a single full-range driver.... no assembly required other than feeding the wire and mounting the driver.... also part of the challenge was to create a 3D-printed housing with no internal supports needed.

    The housing are 7.25" tall and will take about 30 hours each to build. Material is 1.75mm PLA filament (similar to ABS but easier to work with).... then finish and paint. Not sure what color yet.

    One really interesting thing here is that I'm quite confident that there is literally no other way to create this housing in one piece, with zero assembly, other than 3D printing. This shape can't be machined, molded, cast, or even carved as a single part.

    Internal volume is .05 cu ft... port dimensions I can't remember right now, I did the cad work more than a year ago.... the Almighty Mike Zisserson (you still here Mike?) helped me do the calculations, so safe to say the port is optimized for this driver.

    Honestly I'm not expecting stellar sound quality here, as the housing is made of plastic.... on the other hand, as far as plastic housings go this could be pretty good due to the thick walls of .10" (that's quite thick for plastic), and the circular or elliptical shape at any given cross-section lends some inherent rigidity and hoop strength.... The tapering shape of the housing in theory should reduce resonance, but I wouldn't go so far as to call it a "tapered transmission line" or anything, as I've done no such calculations other than to maintain the .05 cu ft internal volume..... who knows maybe the taper will offset the use of plastic somewhat.

    In a nutshell, this is really about the 3D-printing challenge with a unique sculptural form.... certainly not a sound quality build....

    I'd love to hear a discussion about how you all think it will sound. Will it simply be crap due to the plastic? Or will the tapered shape and hoop strength save it? Please share your thoughts.















    The Fountek FE85 has been getting great reviews as a full-range driver, hopefully is does well here.



    The actual 3d prints will start tomorrow. More pictures to follow.

    Cheers.


    Last edited by lunchmoney; 07-29-2020, 09:59 AM.
    Form does not follow function
    Form is simultaneous to function

  • #2
    This is sickkkkkkk. I hope it sounds great as the design is beautiful and appears to have great functionality, only issue possibly being midrange leak due to the port being right behind the driver. Other than that, I love this.
    Builds - C-Killa - Speedsters - LithMTM - Talking Sticks - Pocket Rockets - Khanspires - Dayton RS Center - RS225/28A - Kairos - Adelphos - SEOS TD12X - Dayton 8 - Needles - 871S - eD6c - Overnight Sensations - Tritrix (ported) - Lineup F4 - Stentorians - The Cheapies - Tub Thumpers - Barbells - Tuba HT - Numerous subwoofers - probably missing a few...... :p

    Comment


    • #3
      Yeah, those look pretty cool !

      Comment


      • #4
        Yay! Lunchmoney is back!!!!!

        This looks like it will be another quality Lunch build thread! Can you make a time lapse video of the 3D print? That'd be really cool to see.
        Statements: "They usually kill the desire to build anything else."

        Comment


        • #5
          I think that looks pretty awesome! It looks like it would be tough to print without interior supports, but the port vent would get in the way of getting inside to remove them? Or does your printer have amazing bridging capabilities? It would be a cool experiment to put the vent at the very tail of the spiral. I wish I had the 3D design chops to come up with a model like that!

          Some people have claimed that doing thick walls with low infill helps to isolate the interior of the cabinet from the exterior and improve damping, but I don't think anyone has done any real testing to verify it.

          Comment


          • #6
            • Not sure how far you could reach inside with your fingers or a screwdriver or something, but you might be able to line as much as possible with something like Dynamat. Given the relatively thick plastic and the strength of the curves that might be quite good.
            • I know a lot of the full-range drivers alone benefit from some shaping, can you fit a few small XO components in there if needed?
            You say you are not expecting stellar sound quality but I bet this could sound pretty nice. Looking forward to the results!

            Comment


            • #7
              Originally posted by sychan168 View Post
              I think that looks pretty awesome! It looks like it would be tough to print without interior supports, but the port vent would get in the way of getting inside to remove them? Or does your printer have amazing bridging capabilities? It would be a cool experiment to put the vent at the very tail of the spiral. I wish I had the 3D design chops to come up with a model like that!

              Some people have claimed that doing thick walls with low infill helps to isolate the interior of the cabinet from the exterior and improve damping, but I don't think anyone has done any real testing to verify it.
              In a nutshell, standing hoops (perfect circles especially) can be 3d-printed without internal supports. This is why:
              • At any given vertical cross section the approach to horizontal is gradual.
                • 180 degrees (horizontal) is supported by 179.8 degrees just below it.... which is supported by 179.6 degrees just below that.... etc etc.... (I'm guessing at the increments but you get the idea). This means that the actual overhang of any given layer beyond the layer just below is minimal.
              • The dicey near-horizontal zone doesn't last very long before it meets up with the other side of the circle.
              And the overall geometry of the housing is far better than just a hoop. At any given vertical cross section the dicey horizontal zone at the top is supported by an already-complete hoop just adjacent to it. It's not hanging out there on its own.

              Note in this cross section how the entire housing is essentially all standing hoops. The port needs internal support, but I've done this with a big fat rib rather than adding internal supports.



              Infill? I understand the theory of how it would decouple the interior wall from the exterior wall, but I'm not sure I buy it.... and I could imagine imagine some serious downsides as well. Of course I haven't tried it, but I would theorize:
              • A solid wall is stiffer. Yes, even with honeycomb infill, which is very stiff but doesn't beat a solid wall.
              • The entire housing would weigh a lot less, adding insult to injury for the already lightweight plastic.
              • With infill, I don't see how there's any actual decoupling. The infill would want to be everywhere. I could maybe imagine some "decoupling" happening if some regions had no infill, but then you'd have very thin unsupported regions hanging out in space.
              • The solid inner shells and outer shells would be quite thin and prone to airleaks. Maybe not a big deal if a sealing fluid can be poured into the housing, and I'm certainly going to seal the exterior regardless.
              • At some point too much sound simply leaks through the hollowed-out housing wall.
              • Speaker Gods help you if little bits of errant filament got trapped between the dual walls. They'd be trapped forever in a rattling housing. And they might not be loose initially; they might come loose at a random later date due to your can't stop won't stop Miami Bass habit. Yikes.
              Yes, a design with thicker walls to begin with would make the above concerns much less, but if you're going that route you might as well redesign it as a true double wall, whereby each wall were solid and there was a real strategy to it (connected in critical spots, unconnected elsewhere), rather than connected consistent infill, which I still think wouldn't provide much decoupling. Again, infill is quite stiff.

              Now of course you've got me thinking about an actual proper decoupled design, and I've got actual work to do. Thanks for that ;)
              Form does not follow function
              Form is simultaneous to function

              Comment


              • #8
                Originally posted by john trials View Post
                Yay! Lunchmoney is back!!!!!

                This looks like it will be another quality Lunch build thread! Can you make a time lapse video of the 3D print? That'd be really cool to see.
                Wow that's a really cool idea. Who wants to loan me the camera ;)

                Also: WOOT!!! Nice to be back. Thanks John. Great to see you're still here as well.
                Form does not follow function
                Form is simultaneous to function

                Comment


                • #9
                  Originally posted by lunchmoney View Post

                  In a nutshell, standing hoops (perfect circles especially) can be 3d-printed without internal supports. This is why:
                  • At any given vertical cross section the approach to horizontal is gradual.
                    • 180 degrees (horizontal) is supported by 179.8 degrees just below it.... which is supported by 179.6 degrees just below that.... etc etc.... (I'm guessing at the increments but you get the idea). This means that the actual overhang of any given layer beyond the layer just below is minimal.
                  • The dicey near-horizontal zone doesn't last very long before it meets up with the other side of the circle.
                  And the overall geometry of the housing is far better than just a hoop. At any given vertical cross section the dicey horizontal zone at the top is supported by an already-complete hoop just adjacent to it. It's not hanging out there on its own.

                  Note in this cross section how the entire housing is essentially all standing hoops. The port needs internal support, but I've done this with a big fat rib rather than adding internal supports.



                  Infill? I understand the theory of how it would decouple the interior wall from the exterior wall, but I'm not sure I buy it.... and I could imagine imagine some serious downsides as well. Of course I haven't tried it, but I would theorize:
                  • A solid wall is stiffer. Yes, even with honeycomb infill, which is very stiff but doesn't beat a solid wall.
                  • The entire housing would weigh a lot less, adding insult to injury for the already lightweight plastic.
                  • With infill, I don't see how there's any actual decoupling. The infill would want to be everywhere. I could maybe imagine some "decoupling" happening if some regions had no infill, but then you'd have very thin unsupported regions hanging out in space.
                  • The solid inner shells and outer shells would be quite thin and prone to airleaks. Maybe not a big deal if a sealing fluid can be poured into the housing, and I'm certainly going to seal the exterior regardless.
                  • At some point too much sound simply leaks through the hollowed-out housing wall.
                  • Speaker Gods help you if little bits of errant filament got trapped between the dual walls. They'd be trapped forever in a rattling housing. And they might not be loose initially; they might come loose at a random later date due to your can't stop won't stop Miami Bass habit. Yikes.
                  Yes, a design with thicker walls to begin with would make the above concerns much less, but if you're going that route you might as well redesign it as a true double wall, whereby each wall were solid and there was a real strategy to it (connected in critical spots, unconnected elsewhere), rather than connected consistent infill, which I still think wouldn't provide much decoupling. Again, infill is quite stiff.

                  Now of course you've got me thinking about an actual proper decoupled design, and I've got actual work to do. Thanks for that ;)
                  What i have been doing i lets say your wall is 5mm, setting my wall thickness in my slicer to 2.5mm and it avoids any infill. My cans and phantom clone were 3mm and 5mm and was something i did by mistake but found it pretty sturdy.

                  Comment


                  • #10
                    Originally posted by joeybutts View Post
                    This is sickkkkkkk. I hope it sounds great as the design is beautiful and appears to have great functionality, only issue possibly being midrange leak due to the port being right behind the driver. Other than that, I love this.
                    Thanks!

                    As for "port behind the driver", I thought of that too.... note how the port is not directly behind the driver.... do you think I need to get it even further away? If this is really a problem I would be willing to change it, although the cad is quite tricky to get the port length right etc etc.

                    No bueno?

                    Form does not follow function
                    Form is simultaneous to function

                    Comment


                    • #11
                      Originally posted by 3rutu5 View Post

                      What i have been doing i lets say your wall is 5mm, setting my wall thickness in my slicer to 2.5mm and it avoids any infill. My cans and phantom clone were 3mm and 5mm and was something i did by mistake but found it pretty sturdy.
                      So in other words you're doing a solid wall, yes? The other way to do that is to simply set you infill to 100%. Achieves the same thing, although the paths it takes are different. Shouldn't make any difference structurally.
                      Form does not follow function
                      Form is simultaneous to function

                      Comment


                      • #12
                        Ahh....I see. I have to imagine it would be negligible, and if it was noticeable (I doubt noticeable to the ear) it looks like you have enough space for some thin absorption to take it down even more and not effect bass response.
                        Builds - C-Killa - Speedsters - LithMTM - Talking Sticks - Pocket Rockets - Khanspires - Dayton RS Center - RS225/28A - Kairos - Adelphos - SEOS TD12X - Dayton 8 - Needles - 871S - eD6c - Overnight Sensations - Tritrix (ported) - Lineup F4 - Stentorians - The Cheapies - Tub Thumpers - Barbells - Tuba HT - Numerous subwoofers - probably missing a few...... :p

                        Comment


                        • #13
                          Originally posted by a4eaudio View Post
                          [LIST][*]I know a lot of the full-range drivers alone benefit from some shaping, can you fit a few small XO components in there if needed?
                          Yes I could definitely fit a component or three in there if it would help shape the sound of the FE85.

                          Any ideas? Let's do it!

                          Form does not follow function
                          Form is simultaneous to function

                          Comment


                          • #14
                            As for internal absorption, I'm wondering if there's a thick liquid I could literally pour into the inside, to coat the internal walls with a thin layer, with good acoustic properties.... you can get such a thing in aerosol form, but that wouldn't help me much.... does it come in liquid form?
                            Form does not follow function
                            Form is simultaneous to function

                            Comment


                            • #15
                              Originally posted by joeybutts View Post
                              Ahh....I see. I have to imagine it would be negligible, and if it was noticeable (I doubt noticeable to the ear) it looks like you have enough space for some thin absorption to take it down even more and not effect bass response.
                              Ok cool. Those were Mike Z'z thoughts as well when he evaluated it way back when.
                              Form does not follow function
                              Form is simultaneous to function

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