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  • Pencil Tower

    This is the project that won third place in the Dayton category at MWAF 2012. I'll post the details in this thread.

    The design goal is a narrow tower for LR mains in a 5.1 home theater system. The configuration is mmtmm with 4 of the Dayton ND90-8 and the Dayton ND20FA-6 tweeter.

    The design began life as a cascaded 2.5 with a double chamber reflex enclosure. The design morphed into a simple 2-way reflex design.

    The enclosure is 20 liters.

    The tweeter to mid is crossed at 3,800 Hz.
    The tweeter has a second order filter.
    The woofer has a 3 order filter with an RC shaping circuit, corrected damped 4th order

    More to come
    The response was designed to be flat.
    Attached Files
    Last edited by jhollander; 07-18-2012, 08:01 PM. Reason: damped 4th order is correct
    John H

    SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

  • #2
    Re: Pencil Tower

    I think this is the right pic of the response over simulated. I went through at least 6 x-os before settling on this one. Note the SPL is not accurate.

    The PCD three panel is also shown.
    Attached Files
    John H

    SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

    Comment


    • #3
      Re: Pencil Tower

      Here's unibox and the x-o drawing. I'm pretty happy with the number of components.

      The inductors are all 20 gage. Film and foil cap on the tweeter, electrolytic on the low pass.

      I'll post some construction pics
      Attached Files
      John H

      SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

      Comment


      • #4
        Re: Pencil Tower

        This cabinet is a pain so youve been warned.

        The cabinet is solid oak with a removable back. The back is gasketed with weather stripping. The weather stripping held up better than the speaker gasket foam-tape material.

        There is a middle window brace. There are corner braces and cleats for the removable back. The back is held in place with 14 recessed black pocket screws.

        The drivers are recessed and mounted on a poplar mounting plate. The mounting plate is relieved in the back with a 45 degree chamfer. This is a required step. The mounting plate is covered with felt before being held in place with cleats.

        The ports are mitered 2 inch PVC mounted in PVC flat trim.

        The finish was easier than the cabinet.
        Attached Files
        John H

        SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

        Comment


        • #5
          Re: Pencil Tower

          More construction pics
          Attached Files
          John H

          SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

          Comment


          • #6
            Re: Pencil Tower

            OK last group of construction pics

            The finish will be another day
            Attached Files
            John H

            SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

            Comment


            • #7
              Re: Pencil Tower

              I really liked the finish you put on those cab's, very nice! They sounded pretty good to...
              A mains
              The Ventures
              Open Invit8tions
              RSR
              Sound Troopers
              Acorns
              442
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              • #8
                Re: Pencil Tower

                Yeah you really nailed that finish, it really looks awesome!

                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.

                Comment


                • #9
                  Re: Pencil Tower

                  Oh- YOU'RE jhollander! I gotcha now!!!

                  You did a nice job on the finish, and they sounded pretty good too.

                  FYI- that is technically a damped 4th order electrical on the ND90's.

                  You did much better than last year's horn thingy!
                  Congrats!
                  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:
                  http://photobucket.com/Wolf-Speakers_and_more

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

                  Comment


                  • #10
                    Re: Pencil Tower

                    That's a clever way to hide the pincushion frame. I never would have thought of that.
                    Isn't it about time we started answering rhetorical questions?

                    Paul Carmody's DIY Audio Projects
                    Twitter: @undefinition1

                    Comment


                    • #11
                      Re: Pencil Tower

                      Thanks all.

                      Last years was an experiment. I mistakenly thought that MWAF was a listen-around, talk, get advice, etc. It's much more intense where you need to bring both a good sounding and good looking speaker.

                      John H
                      John H

                      SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

                      Comment


                      • #12
                        Re: Pencil Tower

                        That is a beautiful finish, I love em. Great work on the construction as well. All this with a modeled response that audiophiles love and doctors hate. Great work man.

                        Comment


                        • #13
                          Re: Pencil Tower

                          Why do doctors hate a flat response? Oh haha nvm...

                          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.

                          Comment


                          • #14
                            Re: Pencil Tower

                            i'd like to finish my baffles like this.
                            would you tell me how you got this beautiful finish?

                            Comment


                            • #15
                              Re: Pencil Tower

                              You knocked this one out of the park.

                              Very cool.
                              ~Marty

                              Baby Eidolons
                              Sapphos
                              Cables (Post #54)
                              Other speakers (Post #21)
                              Design Thoughts (Posts: 6,10,13,33,35)
                              Boundary Augmentation
                              Dispersion/Interference

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