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Core 2-Way - Build Tread

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  • MrkCrwly
    replied
    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.

    Leave a comment:


  • Filius
    replied
    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.

    Leave a comment:


  • fastbike1
    replied
    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:

    Leave a comment:


  • MrkCrwly
    replied
    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:

    Leave a comment:


  • Filius
    replied
    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?

    Leave a comment:


  • MrkCrwly
    replied
    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.

    Leave a comment:


  • james_e5
    replied
    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

    Leave a comment:


  • MrkCrwly
    replied
    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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  • MrkCrwly
    replied
    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.

    Leave a comment:


  • MrkCrwly
    replied
    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.

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  • Paul Carmody
    replied
    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

    Leave a comment:


  • Paul Carmody
    replied
    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, 04:45 PM.

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  • MrkCrwly
    replied
    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

    Leave a comment:


  • MrkCrwly
    started a topic Core 2-Way - Build Tread

    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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