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It’s that time audio enthusiasts! Registration for the 2019 Speaker Design Competition is now open! Visit midwestaudiofest.com for details and to list your speaker project. We are excited to see all returning participants, and look forward to meeting some new designers this year, as well! Be sure your plans include a visit to the Parts Express Tent Sale for the lowest prices of the year, and the Audio Swap Meet where you can buy and trade with other audio fans. We hope to see you this summer! Vivian and Jill
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Not so Rat Rocker build thread - Sean's NLA Towers

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  • bkeane1259
    replied
    Re: Not so Rat Rocker build thread - Sean's NLA Towers

    Overall, I'm extremely happy with the sound. The 6.5" subs have more than enough low, punchy bass. The 33Hz tuning seems to be perfect and they work very well in the 1.25ft^3 box. The 3" flared port has absolutely no noise whatsoever, even at high volume.

    The MTM section and my XO shockingly work well. I was lucky....I'm no liar. I got a few nice comments from the folks at InDIYana....thanks for that.

    Soon they will be up in my Sean's room.......He better be nice to the neighbors, because these "not-so-rat rockers" really rock. :D

    Leave a comment:


  • bkeane1259
    replied
    Re: Not so Rat Rocker build thread - Sean's NLA Towers

    I took them to the show just like this (unfinished).....I have not yet decided what to do, finish-wise. My son is not in a rush for anything other than getting them installed in his bedroom. That's good for me. Also, I'd like to wait several months at least and see if anything happens to this hardwood cabinet.....creeping, splitting, etc.



    Leave a comment:


  • bkeane1259
    replied
    Re: Not so Rat Rocker build thread - Sean's NLA Towers

    Box stuffing/lining. Late last year I did some experimentation with open cell memory foam. Basically it works really well if you use it on the rear wall of the cabinet. There's no need to line every surface. It actually worked better just being on the rear wall. It works surprisingly well at sucking up midrange frequencies but it also seems to enhance the low end a bit. So for this build I'm putting memory foam bats on the rear wall, in both chambers. Then, in the bottom chamber, I also used Walmart mattress topper. The sealed MTM section will be filled with Roxul....not overly stuffed, but about half way stuffed, in addition to the memory foam on the rear wall.



    Gasket tape to help seal the baffle:

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  • bkeane1259
    replied
    Re: Not so Rat Rocker build thread - Sean's NLA Towers

    The case for the SA240:





    The XO components. I pieced together a few different components to get the correct values. After what felt like putting together a jigsaw puzzle, I got everything within 0.5% of the calculated values.







    Stuck the XO's in the sealed MTM chamber.

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  • bkeane1259
    replied
    Re: Not so Rat Rocker build thread - Sean's NLA Towers

    Dayton SA240




    A slight mod to the SA240. Since I want a full range signal to come out of the hi-level section of the amp for the pass-through to the MTM, I have to open up the amp and take out the factory-installed caps.

    Dayton uses a first order high-pass filter on the hi-level outputs which is basically a NPE cap.





    Some heat-shrink tubing on the spliced sections of wire.





    Leave a comment:


  • bkeane1259
    replied
    Re: Not so Rat Rocker build thread - Sean's NLA Towers

    Don't try to flush trim 1" stock with a 1/4" bit.



    This is what happens:



    Out comes my friend, Mr. Bondo.

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  • bkeane1259
    replied
    Re: Not so Rat Rocker build thread - Sean's NLA Towers

    I'm making the front baffle removable. Using these threaded inserts and bolts from Meniscus.



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  • bkeane1259
    replied
    Re: Not so Rat Rocker build thread - Sean's NLA Towers

    Unclamped and ready for a lot of sanding.





    Cutouts for the ports. The exit flare requires a pretty large cutout. The port diameter is 6.5".





    Also installed binding posts:



    Leave a comment:


  • bkeane1259
    replied
    Re: Not so Rat Rocker build thread - Sean's NLA Towers

    I used a 45deg chamfer bit on the woofer cutouts and a cove bit for the mids. I had to take out a fair amount of stock for the mids....







    The NS35 flanges are a real PITA. There's basically NO flange at 4 points on the underside, so not only does the cutout need to be perfect, but you still have to use some sort of gasket or seal if you want an air-tight fit.

    Leave a comment:


  • bkeane1259
    replied
    Re: Not so Rat Rocker build thread - Sean's NLA Towers

    Driver cutouts.



    I have a template for the truncated BC25 that I made last year. It's not perfect, but it gets me very close.







    Leave a comment:


  • bkeane1259
    replied
    Re: Not so Rat Rocker build thread - Sean's NLA Towers

    One of these days I am going to have a nice square joint....but not today unfortunately. Story of my life.







    Leave a comment:


  • bkeane1259
    replied
    Re: Not so Rat Rocker build thread - Sean's NLA Towers

    Here's the layout. The subs will be in a ported 1.25ft^3 (after bracing, etc) chamber, with a 3 I.D. x 11" flared PE buyout port. Tuning is 33Hz and modeled F3 is 30.2Hz. The MTM portion will be sealed in about 0.35ft^3.



    I'm using mostly poplar, but also some 1/2" ply for braces and the MTM shelf.



    The braces:











    Leave a comment:


  • bkeane1259
    replied
    Re: Not so Rat Rocker build thread - Sean's NLA Towers

    I'm very old-school, so:



    and....



    and the XO schematic:

    Leave a comment:

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