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  • Aperiodic/variovent ideas?

    As mentioned in my other thread, I have these ADS 10" drivers with rather high Qts (.69) as measured by a WT2.

    My thought is, I'd like to try an aperiodic loading. Now that I have the WT2, I should be able to adjust the density in my stuffed port to minimize the impedance peak, which I think is the goal.

    BUT... The Scan-Speak aperiodic "things" are quite expensive ($20 each?), and it isn't clear that they really offer a means to make adjustments to them. They seem to indicate a quantity to use depending on the size of the enclosure, but that doesn't seem so helpful.

    The thing I LIKE about them, though, is that they look pretty decent. The old Dynaco speakers with the slot cut and filled with foam rubber, and then covered with screen, isn't that charming a look. And quite frankly, it still doesn't offer much way of making adjustments.

    Has anyone here come up with a low cost/easy to adjust/nice looking aperiodic vent device using off-the-shelf materials?

    TIA.

    As an add-on Q, I've been using WinISD but there is no way it seems to model a sealed enclosure with a aperiodic port. I can specify Ql for a ported enclosure, but not a sealed enclosure.

    I've seen people talk about Unibox but that seems to require Excel (any compiled v's that don't require Excel?).

    Any other tools out there that would allow me to model a sealed enclosure that is lossy?

    Thanks!

  • #2
    Re: Aperiodic/variovent ideas?

    I haven't built one, but I'd think varying the amount of stuffing should adjust the Q.
    Francis

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    • #3
      Re: Aperiodic/variovent ideas?

      Originally posted by fpitas View Post
      I haven't built one, but I'd think varying the amount of stuffing should adjust the Q.
      Right but it doesn't look like the ones being sold commercially are really designed for easy fiddling.

      I was it all. I was easy fiddling, I was it to look nice, and I want it to be inexpensive and easy to implement.

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      • #4
        Re: Aperiodic/variovent ideas?

        Originally posted by philthien View Post
        As mentioned in my other thread, I have these ADS 10" drivers with rather high Qts (.69) as measured by a WT2.

        My thought is, I'd like to try an aperiodic loading.


        With that one, consider trying the MAPD alignment. See the white paper at the link below authored by George Short, North Creek Music Systems.

        http://www.northcreekmusic.com/MAPD1.htm

        edit: I modify the suggestion to a third order sealed alignment (BW3 acoustic highpass) using a first order high pass in combination with the second order rolloff provided by the MAPD alignment, which is an acoustic suspension loading with improved linearity provided by the aperdiodic damping.

        The succinct white paper above is based on his masters thesis, available at the link below. At 120 pages, the thesis goes into considerably more detail. Start with the white paper.

        http://scholar.lib.vt.edu/theses/ava..._1988.S432.pdf
        "Our Nation’s interests are best served by fostering a peaceful global system comprised
        of interdependent networks of trade, finance, information, law, people and governance."
        - from the October 2007 U.S. Naval capstone doctrine
        A Cooperative Strategy for 21st Century Seapower
        (a lofty notion since removed in the March 2015 revision)

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        • #5
          Re: Aperiodic/variovent ideas?

          Originally posted by JRT View Post
          With that one, consider trying the MAPD alignment. See the white paper at the link below authored by George Short, North Creek Music Systems.

          http://www.northcreekmusic.com/MAPD1.htm
          This time around I'm going to go with a more "conventional" aperiodic enclosure.

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          • #6
            Re: Aperiodic/variovent ideas?

            You could modify the setup I used for my Bulldogs. Instead of gluing an inner baffle piece over the blocks of dampening material you could use nuts and bolts. That would allow you to adjust all of the variables other then hole size at will.
            http://jaysspeakerpage.weebly.com/

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            • #7
              Re: Aperiodic/variovent ideas?

              Phil I’ve seen a few guys use a PVC shower drain fitting and layer wool batting in the opening and use PVC pipe to hold it in place. For me I’ve just drilled holes. I used a 3/8 inch hole in one build but I think multiple smaller holes would be better.
              John H

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

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