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3D printed waveguides

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  • I hope you won't mind a few questions? I'm curious about the cross section, was it an arc tangent to the baffle surface, ending at the throat, and did you remove the stock face plate? Do you recall if it was milled in a terrace pattern, using a step down, for example .01", or was the milling done stepping over? Did you use MDF?

    What you've described is similar to what Takitaj found a few years ago testing an early oval guide I did, coincidentally he had done a shallow oval(as I recall) guide that tested similarly. Ryan Bouma found the same result testing a very similar guide. As DanP pointed out, I hope I'm paraphrasing correctly, there is no magic in guide geometry, depth and contour can be manipulated to produce a desired effect.

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    • Pete would you have some measurements of just the tweeter?
      ~Brandon

      Soma Sonus
      DriverVault

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      • Check the link in my signature to the 8" 2-way. Toward the end of that thread I mention the 1" deep guides pictured below. I made an elliptical as well as a round guide. Both ended tangentially to the baffle surface and carried simple circular arcs to the throat opening. Here the elliptical has been sanded (but not sealed). Completely smooth to 400grit in only 10 minutes.





        Here's some response plots from page 22 of that thread. The RS28A in the elliptical is the green plot. The blue is the 27TBFC in the elliptical. The red is RS28A in the circular guide. To me, the red plot is closest to the ideal with the most extended top end response and as you can see, about 10dB of "gain" compared to the response at 15KHz



        Click image for larger version

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        And finally, the system response with the current crossover.

        Click image for larger version

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        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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        • looks a lot like Behringer Truth 8031! Not a bad thing.

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          • रेतुर्न तो थे स्रोत
            return to the source
            leviathan system thread
            deadhorse thread
            shockwave build thread

            instagram :: greywarden_13

            in war, victory . . . in peace, vigilance . . . in death, sacrifice.

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            • For those who want a WG for a 7-8" woofer, why reinvent the wheel?

              http://www.diysoundgroup.com/plastic...8-tweeter.html
              "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche

              http://www.diy-ny.com/

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              • Originally posted by Face View Post
                For those who want a WG for a 7-8" woofer, why reinvent the wheel?

                http://www.diysoundgroup.com/plastic...8-tweeter.html
                Sometimes you want a baffle that looks seamless.

                I've even worked up a couple of kits using the SEOS-8 for the RS225P and the 8BG51 and RS28A. It's a nice little guide and works quite well.

                But I think I like my shallower guide even better. But it does require more work to finish it than using the SEOS.
                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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                • Guides in solid wood can be very attractive, especially if it is a double guide combining tweeter and midrange, or tweeter and small woofer. Shrinkage and expansion can be a minor problem, as the openings vary out of round ~1-2%, changing the throat from round to oval, but that is not too noticeable. I don't know how it affects the guides effect on sound.

                  I agree though that if something is available off the shelf that works, printing new guides makes no sense, given the cost and time, 3D printing is a slow process. The surface finish can also be a problem, it is not nearly as smooth as a molded surface, although future printing processes and filaments may improve that.

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                  • I agree, I would love for a SEOS 8 cut in a solid wood baffle. Although, this kind of works too: https://imgur.com/8hnuKlk
                    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche

                    http://www.diy-ny.com/

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                    • Do you have one of the guides? Perhaps it can be duplicated in wood, provided it's legal to do so. I haven't worked with a guide using that rectangular shape yet, it might be interesting to do so. Could you or someone else test the result, and compare the data to the original?

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                      • I've always wanted to build something similar to the Fern & Roby Beam speakers. I think that's my next project after I finish the Shockwave speakers

                        रेतुर्न तो थे स्रोत
                        return to the source
                        leviathan system thread
                        deadhorse thread
                        shockwave build thread

                        instagram :: greywarden_13

                        in war, victory . . . in peace, vigilance . . . in death, sacrifice.

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                        • Greywarden,

                          I found the website, it's an interesting idea, do you know what is inside the cabinets, are they bass reflex, sealed, maybe T/L. It would be easy to do a quick baffle in MDF if you want to try a prototype.

                          tna

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                          • I don't want to step on Erich's toes copying one of his designs, protected or not. Besides we're swimming in different pools as far as application.

                            Pete> Could estimate the AC offset in your latest speaker (with crossover in place)? When we get to the 8" guide I'm guessing we'll have trade off in depth required - probably shallowish for response, and deeper to match AC.
                            ~Brandon

                            Soma Sonus
                            DriverVault

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                            • I didn't recess the B&C woofer completely flush since the flange is so thick. So right now the offset is basically zero. If the woofer was completely flush then I think a 1.25" thick baffle would be about perfect to keep the alignment. Maybe even 1.125"
                              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


                              • If the woofer was completely flush then I think a 1.25" thick baffle would be about perfect to keep the alignment. Maybe even 1.125"
                                In other words the depth of the guide is the same as the depth of the baffle?
                                ~Brandon

                                Soma Sonus
                                DriverVault

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