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Fibonacci Spiral for Horns

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  • Fibonacci Spiral for Horns

    Setting aside the complexity of building a horn based upon a Fibonacci spiral, or perhaps another exponential spiral, would there be an acoustic advantage to such a horn?

    If so, and if building it were not a serious impediment, would anyone want to collaborate and be willing to provide the mathematical data to define the horn shape?

  • #2
    Re: Fibonacci Spiral for Horns

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    • #3
      Re: Fibonacci Spiral for Horns

      Originally posted by TN Allen View Post
      ...Would there be an acoustic advantage to such a horn? ...
      One aspect of various horn flair rates is what Beranek called Radiation resistance ( particularly near cutoff ).
      For practice reason large horns are usually made with flat wooded panels, not curved.
      "Not a Speaker Designer - Not even on the Internet"
      “Pride is your greatest enemy, humility is your greatest friend.”
      "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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      • #4
        Re: Fibonacci Spiral for Horns

        Do the practical reasons result from Radiation resistance or construction difficulty?

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        • #5
          Re: Fibonacci Spiral for Horns

          Construction difficulty - Most bass horns I have seen ( that used curved panels ) were made from a molded/sprayed or formed material like fiberglass.
          Here is a "classic" examination.
          "Not a Speaker Designer - Not even on the Internet"
          “Pride is your greatest enemy, humility is your greatest friend.”
          "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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          • #6
            WinPCD - Windows .NET Passive Crossover Designer

            Dave's Speaker Pages

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            • #7
              Re: Fibonacci Spiral for Horns

              Here are a couple of links on ebay to sellers touting the benefits of the fib horn

              http://www.ebay.com/itm/AUDIOPHILE-F...item417e4f8eb7

              http://www.ebay.com/itm/FIBHORN-4tbb...item3f335cb098

              http://www.ebay.com/itm/FIB-HORN-4tb...item417e5f7978

              bare cabinets for $299 a pair, with a TB 3" 881 SIF $378, and in a "stone" cabinet $999. Here is some of the hype.

              How do we do it? By placing a superb full-range TANG BAND 3" driver into our unique FIBHORN 4 speaker cabinet, with four FIBONACCI (exponentially expanding) chambers that together form almost 36" of perfect horn for the back wave of the driver. It yields a flat bass to 38hz PLUS accurate equalization of all frequencies to 20,000hz.

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              • #8
                Re: Fibonacci Spiral for Horns

                Originally posted by TN Allen View Post
                Setting aside the complexity of building a horn based upon a Fibonacci spiral, or perhaps another exponential spiral, would there be an acoustic advantage to such a horn?
                Not really. It has the advantage of being easier to lay out than conic sections, as it consists of a series of constant radius bends. I use it in my DR horns for that reason.
                As for this:
                How do we do it? By placing a superb full-range TANG BAND 3" driver into our unique FIBHORN 4 speaker cabinet, with four FIBONACCI (exponentially expanding) chambers that together form almost 36" of perfect horn for the back wave of the driver. It yields a flat bass to 38hz PLUS accurate equalization of all frequencies to 20,000hz.
                A 36 inch long horn will only load to 94Hz. A horn mouth that small won't even go that low. It may appear to be a horn to the uninformed, but between the short length and mouth area it will actually operate as a tapered port.
                Last edited by billfitzmaurice; 07-10-2014, 11:27 PM.
                www.billfitzmaurice.com
                www.billfitzmaurice.info/forum

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                • #9
                  Re: Fibonacci Spiral for Horns

                  Not anymore, J-M Le C has died.

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                  • #10
                    Re: Fibonacci Spiral for Horns

                    Originally posted by clydethecat View Post
                    Not anymore, J-M Le C has died.
                    He frequently requested features and model enhancements from Dave McBean, the author of HornResp. If this is a direction you'd like to explore, HornResp probably has the calc models.

                    Regards,

                    Rob

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