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Core 2-Way - Build Tread

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  • Core 2-Way - Build Tread

    A while back I decided to construct Paul Carmody's Amiga or a variant. Since the RS180s were no longer available I talked to Paul about a new version with the new non shielded RS180-8 and the popular RS28F. That thread can be viewed here:
    http://techtalk.parts-express.com/sh...ighlight=amiga

    Paul kindly agreed to give it a try, so I had PE ship him the RS180-8 and the RS28F so he could work his magic. With a pinch of lizard leg and some eye of newt, the Core was born. (I may be wrong about the design methodology but hey I'm just a cabinet builder so what do I know.) Actually 2 versions of the Core are being hatched. One with the RS28F and one with its brother the RS28A. I'm sure Paul will post the designs to his web site as they are finalized.
    http://sites.google.com/site/undefinition/diy

    I will construct the cabinets with heavy flake quarter sawn white oak veneer with solid oak cap and base. Walnut accent wings will be contructed below the top.
    I have already cut the mdf and some parts of the cabinets have been biscuited and glued. I hope to post some progress pics this weekend.

    Click image for larger version

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    Mark
    My TriTrix Build
    My Core 2 Way Build
    My RSS315HF-4 Subwoofer Build

  • #2
    Re: Core 2-Way - Build Tread

    Attached are my construction drawings. Note that these drawings do not fully follow Pauls original cabinet that was used in the design of the crossovers. See Paul's site for the "official" cabinet design.
    http://sites.google.com/site/undefinition/diy-trs-80
    http://sites.google.com/site/undefinition/diy/amiga

    Core - A101.pdf Core - A102.pdf Core - A103.pdf
    Mark
    My TriTrix Build
    My Core 2 Way Build
    My RSS315HF-4 Subwoofer Build

    Comment


    • #3
      Re: Core 2-Way - Build Tread

      Originally posted by MrkCrwly View Post
      Paul kindly agreed to give it a try, so I had PE ship him the RS180-8 and the RS28F so he could work his magic. With a pinch of lizard leg and some eye of newt, the Core was born. (I may be wrong about the design methodology but hey I'm just a cabinet builder so what do I know.)
      Yeah, it's something like that. Sometimes I hold a seance to invoke the spirits of Henry Kloss and Harry F. Olson. :D

      Anyway, the crossovers are all done. I'll post them here. I just wanted to take some off-axis measurements first. Should have those done in the next few days.
      Last edited by Paul Carmody; 12-17-2010, 03:45 PM.
      Isn't it about time we started answering rhetorical questions?

      Paul Carmody's DIY Audio Projects
      Twitter: @undefinition1

      Comment


      • #4
        Re: Core 2-Way - Build Tread

        All right, here we go with crossover diagrams, and lots of graphs.

        First, here is the crossover diagram for the aluminum version


        The crossover for the silk version is exactly the same, except that you omit cap C4 on the tweeter circuit.

        Here's the simulated Frequency Response


        And the Impedance. Nice n' safe.


        And here are some actual measurements. These have a fairly short window, because the floor bounce shows up pretty early otherwise. You can see that there is a dip centered around 3 KHz. This is always going to happen with a tweeter centered on an 8" wide baffle. The dip goes away once you move off-axis a bit.
        100cm on-axis.


        This is my preferred listening position: speakers pointed straight ahead, me at the center.
        Attached Files
        Isn't it about time we started answering rhetorical questions?

        Paul Carmody's DIY Audio Projects
        Twitter: @undefinition1

        Comment


        • #5
          Re: Core 2-Way - Build Tread

          Click image for larger version

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          Top ready to biscut to side panel.
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          Top glued.
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          Back attached.
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          Stops for removeable crossover access panel on bottom of rear.
          Mark
          My TriTrix Build
          My Core 2 Way Build
          My RSS315HF-4 Subwoofer Build

          Comment


          • #6
            Re: Core 2-Way - Build Tread

            Click image for larger version

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            View of cabinet without front baffle attached.
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            Window Brace - Baltic Birch
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            Back of Cabinet
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            Low Head Cap Screw and Inserts.
            So far I am really impressed with how easy it is to install the inserts.
            Mark
            My TriTrix Build
            My Core 2 Way Build
            My RSS315HF-4 Subwoofer Build

            Comment


            • #7
              Re: Core 2-Way - Build Tread

              Here is the bill of materials for both the RS28A and RS28F versions of the Core 2-Way. Please let me know if you see any mistakes. (Paul: I added better descriptions in this version vs what I sent you previously. I will send you an updated xls.) Note: The Cross Over diagram shows C2 as a .11 uf cap. The BOM shows C2 as a .10 cap and this is acceptable.

              Click image for larger version

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              Mark
              My TriTrix Build
              My Core 2 Way Build
              My RSS315HF-4 Subwoofer Build

              Comment


              • #8
                Re: Core 2-Way - Build Tread

                Nice, clean work Mark!

                Say, where did you purchase those hex head screws and inserts? Those look like they would come in handy!

                -j

                Comment


                • #9
                  Re: Core 2-Way - Build Tread

                  Originally posted by james_e5 View Post
                  Nice, clean work Mark!

                  Say, where did you purchase those hex head screws and inserts? Those look like they would come in handy!

                  -j
                  In a thread about inserts someone here mentioned MSC and the EZ-Lok inserts. My son belongs to a Toyota Land Cruiser club that has an account at MSCDirect and he got them for me. The screws look just like the screws in the RS29 tweets.
                  http://www1.mscdirect.com/CGI/NNSRIT...PMPXNO=2072123
                  http://www1.mscdirect.com/CGI/NNSRIT...PMPXNO=8217907

                  Even better my son bought me the parts from MSC to plumb compressed air in my workship and garage. Now that is a great Xmas present.
                  Mark
                  My TriTrix Build
                  My Core 2 Way Build
                  My RSS315HF-4 Subwoofer Build

                  Comment


                  • #10
                    Re: Core 2-Way - Build Tread

                    I don't claim to know what I'm talking about, at all. But I thought I read somewhere that you don't want any overhanging edges on the baffle. It interferes with the soundwaves or something? I love the cabinet design, sort of a neo-classical look, but I thought those kinds of protrusions on the front of a speaker were a no-no. Am I misinformed?

                    Comment


                    • #11
                      Re: Core 2-Way - Build Tread

                      Originally posted by Filius View Post
                      I don't claim to know what I'm talking about, at all. But I thought I read somewhere that you don't want any overhanging edges on the baffle. It interferes with the soundwaves or something? I love the cabinet design, sort of a neo-classical look, but I thought those kinds of protrusions on the front of a speaker were a no-no. Am I misinformed?
                      Yes that is true. Every surface will affect the sound.
                      I do not claim to be a "speaker" designer and hope I make it clear that I leach off of others (so far it is Curt and Paul) for the guts. I included a disclaimer in one of my early posts: "Note that these drawings do not fully follow Pauls original cabinet that was used in the design of the crossovers. See Paul's site for the "official" cabinet design."
                      That said I do try and minimize the effects my changes have on the original speaker sound. In this case I only used horizontal elements and I have convinced myself that the top acts as a wave guide.
                      Of course if I find out that my speakers sound like crap I can easily correct that with a new power cord or silver speaker wire.:rolleyes:
                      Mark
                      My TriTrix Build
                      My Core 2 Way Build
                      My RSS315HF-4 Subwoofer Build

                      Comment


                      • #12
                        Re: Core 2-Way - Build Tread

                        I don't know Mark, maybe you should just glue one of the Hologram bracelets to the top or write happy thoughts with the magic red pen.

                        I suspect the esthetic treatments are unlikely to cause audible problems.

                        Originally posted by MrkCrwly View Post
                        Of course if I find out that my speakers sound like crap I can easily correct that with a new power cord or silver speaker wire.:rolleyes:
                        I was so much older then, I'm younger than that now.
                        OS MTMs http://techtalk.parts-express.com/sh...d.php?t=220388
                        Swope TM http://techtalk.parts-express.com/sh...d.php?t=221818
                        Econowave and Audio Nirvana AN10 fullrange http://techtalk.parts-express.com/sh...d.php?t=216841
                        Imperial Russian Stouts http://techtalk.parts-express.com/sh...=1#post1840444
                        LECBOS. http://techtalk.parts-express.com/sh...ghlight=lecbos

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                        • #13
                          Re: Core 2-Way - Build Tread

                          Well anyway, the design is ingenious. I hope to make a feeble attempt at copying it. Have you made any further progress since you last posted pics? I especially want to know your listening impressions. I had almost decided to do the Amigas when I heard about the Cores and now I'm in a quandary.

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                          • #14
                            Re: Core 2-Way - Build Tread

                            Originally posted by fastbike1 View Post
                            I don't know Mark, maybe you should just glue one of the Hologram bracelets to the top or write happy thoughts with the magic red pen.
                            Good point. I could probably get a "factory refurbished" bracelet on the cheap.
                            Mark
                            My TriTrix Build
                            My Core 2 Way Build
                            My RSS315HF-4 Subwoofer Build

                            Comment


                            • #15
                              Re: Core 2-Way - Build Tread

                              Originally posted by Filius View Post
                              Well anyway, the design is ingenious. I hope to make a feeble attempt at copying it. Have you made any further progress since you last posted pics? I especially want to know your listening impressions. I had almost decided to do the Amigas when I heard about the Cores and now I'm in a quandary.
                              Thank you. I have the baffle routed for speakers and just will glue it on as soon as I find some open cell foam to line the walls. The oak caps and base are cut and ready to sand.
                              Paul Carmody would be better to ask about the sound since he has recently heard the Amigas and designed the Core. The Amiga's tweet costs less so that may be your best bang for the buck. I'm a visual guy and I love the look of the RS28A/F. Not sure there is a wrong or right choice just preferences.
                              Here is Paul's Core 2 Way design link that may help:
                              http://sites.google.com/site/undefin...aytonrs180rs28
                              Mark
                              My TriTrix Build
                              My Core 2 Way Build
                              My RSS315HF-4 Subwoofer Build

                              Comment

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