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Build Thread: The Bombers (SR71's become 3-ways)

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  • Build Thread: The Bombers (SR71's become 3-ways)

    So finally pulling the trigger on this. Been threatening to for a while, the time has come... the layer of dust that has collected on the RS270's is juuuuussst right...

    These were previously named the HobGoblins... it's now been changed to The Bombers, to pay some homage to the SR71's.

    So I already have SR71's (ER18RNX + 27TBFCG), which I adore... but I also crave big 3-ways, and I have a pair of RS270-8's just sitting around (Dayton Reference 10")... so with the help of Michael Zisserson The Almighty, the SR71's and RS270's are being combined into an all new 3-way design... Mike's crossover design will be posted later.

    So this thread will focus on the bass cabinets. If you'd like to see more about the SR71 cabinets, go here:

    http://techtalk.parts-express.com/sh...d.php?t=208196

    So here we go... The bass cabinets are 1.5 cu ft sealed, made from 1/2" baltic birch... I was tempted to go vented, but I still plan on using a sub, and the vented ones got really goofy looking because they were quite a bit bigger... not like these are going to win any beauty contests, but might as well control the bleeding...

    No, the upper cabinets are not set back... they are flush to the fronts of the bass cabinets, with a 1/2" gap (this gap makes it look like they're set back)...




    First I will construct the bracing structure. The 1.5" radius rounds on the front corners will be made on the lathe/milling machine. The short bits along the edges will just be scraps of 3/4" mdf. Center post is a 1" oak dowel.






    Next I will quite literally wrap a piece of plywood around the bracing structure. The plywood will have dato cuts in it to accept the window braces. The large curved radii on the back will be kerf cut, and possibly soaked in water first if necessary (kerf cuts not shown)






    Then the top, bottom, and baffle simply glue on. The baffle will also have dato cuts to accept the window braces.

    Cabinets will be veneered with a very dark wood of some kind... or maybe not so dark then stained dark.

    Here is MikeZ's crossover design...




    And the PCD plot thingy something or other...



    Build starts this weekend!
    Last edited by lunchmoney; 01-13-2012, 12:52 PM.

  • #2
    Re: Build Thread: The Bombers (SR71's become 3-ways)

    I see a lot of designs using stacked cabs. I always wonder, do you guys not worry about reflection issues of the bottom cab given its extended beyond the top?
    ErinsAudioCorner.com

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    • #3
      Re: Build Thread: The Bombers (SR71's become 3-ways)

      Originally posted by ErinH View Post
      I see a lot of designs using stacked cabs. I always wonder, do you guys not worry about reflection issues of the bottom cab given its extended beyond the top?
      Not entirely sure what you mean, can you elaborate?

      The only reason these are stacked is because I'm repurposing the existing cabinets of the SR71's...

      Although there is definitely some advantage to it, as the baffle dimensions of the upper cabinet have already been designed to work well with the mid and tweeter.

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      • #4
        Re: Build Thread: The Bombers (SR71's become 3-ways)

        Originally posted by lunchmoney View Post
        Not entirely sure what you mean, can you elaborate?

        The only reason these are stacked is because I'm repurposing the existing cabinets of the SR71's...

        Although there is definitely some advantage to it, as the baffle dimensions of the upper cabinet have already been designed to work well with the mid and tweeter.
        He's saying the sound radiation that travels along the baffle downward will hit two new square edges before going to the floor.

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        • #5
          Re: Build Thread: The Bombers (SR71's become 3-ways)

          Originally posted by lunchmoney View Post
          Not entirely sure what you mean, can you elaborate?

          The only reason these are stacked is because I'm repurposing the existing cabinets of the SR71's...

          Although there is definitely some advantage to it, as the baffle dimensions of the upper cabinet have already been designed to work well with the mid and tweeter.
          I think Erin was asking about diffraction from the woofer bins which may be an issue.

          Comment


          • #6
            Re: Build Thread: The Bombers (SR71's become 3-ways)

            SICK

            That cab will be amazing. I wish I can design a cab line that...Never mind design but BUILD.
            .

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            • #7
              Re: Build Thread: The Bombers (SR71's become 3-ways)

              Originally posted by ErinH View Post
              I see a lot of designs using stacked cabs. I always wonder, do you guys not worry about reflection issues of the bottom cab given its extended beyond the top?
              Diffraction will not be too big of an issue. When design, driver spacing and a rough baffle width was accounted for for step. Should be close enough to hone in once a x-over is built.
              .

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              • #8
                Re: Build Thread: The Bombers (SR71's become 3-ways)

                Looks nice. Is this setup going to be completly passive?

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                • #9
                  Re: Build Thread: The Bombers (SR71's become 3-ways)

                  Originally posted by killa View Post
                  Looks nice. Is this setup going to be completly passive?
                  Yes, but maybe active someday if I ever get the equipment for it...

                  Comment


                  • #10
                    Re: Build Thread: The Bombers (SR71's become 3-ways)

                    Originally posted by mzisserson View Post
                    SICK

                    That cab will be amazing. I wish I can design a cab line that...Never mind design but BUILD.
                    Thanks Mike! Looking forward to some voicing sessions with you once it's built.

                    Comment


                    • #11
                      Re: Build Thread: The Bombers (SR71's become 3-ways)

                      Awesome! I will be following as I have the 8's already. The Statements I built with and for my brother absolutely rock with 2 of the 8's ported in approx 4 cu ft. Build it!!:D
                      Audiophiles listen to the equipment, not the music.

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                      • #12
                        Re: Build Thread: The Bombers (SR71's become 3-ways)

                        Originally posted by Steve Henry View Post
                        Awesome! I will be following as I have the 8's already. The Statements I built with and for my brother absolutely rock with 2 of the 8's ported in approx 4 cu ft. Build it!!:D
                        The RS270 is the 10", you have the RS225.
                        Bummer,
                        Wolf
                        "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
                        "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
                        "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
                        "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

                        *InDIYana event website*

                        Photobucket pages:
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                        My blog/writeups/thoughts here at PE:
                        http://techtalk.parts-express.com/blog.php?u=4102

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                        • #13
                          Re: Build Thread: The Bombers (SR71's become 3-ways)

                          Is the new crossover going to change the original SR71 crossover much? I want to buy the SR71 kit but now I want to do this! If the crossover is a complete re-do I will hold off on the kit and buy components individually.


                          VERY EXCITED FOR THIS BUILD!
                          My Build Blog: LHark Audio

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                          • #14
                            Re: Build Thread: The Bombers (SR71's become 3-ways)

                            Originally posted by Wolf View Post
                            The RS270 is the 10", you have the RS225.
                            Bummer,
                            Wolf
                            My bad! I gotta get off the Hydrocodone.
                            Audiophiles listen to the equipment, not the music.

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                            • #15
                              Re: Build Thread: The Bombers (SR71's become 3-ways)

                              "I picked the wrong day to stop sniffing glue" :D

                              Looks pretty frackin cool man.

                              रेतुर्न तो थे स्रोत
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                              in war, victory . . . in peace, vigilance . . . in death, sacrifice.

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