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  • Re-Nubby with Questions

    After a 45 year hiatus I have decided to get back into speaker building. I have finished the 12 in subwoofer and now am ready to build some bookshelf speakers. About a year ago I bought a pair of DA DC28F tweeters and a pair of Acoustic Research 1210163-5 6 1/2 in Poly Cone woofers. I also bought Dickason's LDC and Alden's SB 201. After reading those books I am not sure if the two drivers are a good choice. So my first question is are these drivers a good choice and has anyone made the perfect(LOL) bookshelf speaker from them? If this is not a good match up then could you recommend a 6 1/2in driver to go with my tweeters?

    My second question is related to the calculated sealed box volume. Why are the hand calculated volumes for sealed enclosures always greater than the volumes calculated by BassBox 6? Most of the time I have to use a Qtc greater than 0.8 to match the BassBox volumes. I have made calculations for more than10 drivers to reach this conclusion. I have not found anywhere in the PE information a statement concerning what Qtc they use in BassBox.

    My final question (for this round) is once I have your recommendation for a proper alignment (I hope this is the correct term) I will need someone to help me with the crossover design. I could make a simple crossover but I have seen some really nice schematics on this site. I would like a more sophisticated crossover for my speakers.

    Thank you for any help you care to give me. Paul

  • #2
    Welcome to the forum!

    If you have a sub, and plan sealed box mains, the box volume is not important, as long as you don't go way small. Too big can be remedied by adding solid filler. I prefer a larger box with lots of dense fiberglass in the box.

    I like the Peerless 830874 6.5" HDS poly cone driver. It can cross over high, or low. I use it in my 2-ways, on stands, out away from the wall, so my x-overs are full BSC.

    If you go with Dayton drivers, the x-over can be roughed out using the supplied measurements and x-over software. Some of the software is free!

    If you get set up to measure, you can make almost anything you want.

    If you want to build someone else's design that uses the DC28, I'm sure there's a few out there. In looking at the specs, it looks to me like it should work crossed at 2k or higher, so it should work with your AR as long as it will cross at 2k or higher. Do you have any measurements for the AR?

    So, you can use software to design the x-over, or you can work by trial and error if you measure. I like trial and error, but if you don't have lots of x-over parts on hand, the software can get you close.

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    • #3
      What size box are you looking at? If 0.75cf is OK, why not vent it? Do you use the FREE WinISD (from linearteam.org ) to model boxes for F3?
      If you want sealed, are you looking for a Q near 0.70? WinISD says you'd need to go w/1.1cf (sorta large for a 6" closed box). A 0.9cf box that's well-stuffed should end up fairly equivalent, Q-wise.

      PE's got T/S (box ) data for that driver, but I don't know of any freq. measurements from anywhere. To design a (decent) XO you need impedance and FR plots for for speakers. The -070 ("Silky") is no problem, but the AR is.

      If this is "non-critical", I'd take a best guess for the woofer's FR/ and Z (impedance) and sim an XO for you.

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      • #4
        Not famiiar with bassbox6 but most of us here use WinISD or Unibox for enclosure modeling. They're free and easy to use.

        Unibox can be found elsewhere but Google hit this first http://audio.claub.net/software/kougaard/ubdwnld.html

        WinISD can be found here http://www.linearteam.org/

        http://techtalk.parts-express.com/fo...khanspires-but
        http://techtalk.parts-express.com/fo...pico-neo-build
        http://techtalk.parts-express.com/fo...ensation-build

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