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Flex Your PCD Mettle:

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  • #31
    Re: Flex Your PCD Mettle:

    Originally posted by Zilch View Post
    The new set of FRDs was taken from a single point in space, at the midpoint between the drivers and on axis horizontally, so the responses would include the relative offsets.

    They include minimum phase. I don't know how CLIO calcs that, but I did not alter the time window.

    I also provided the same measurement for the two drivers combined, from which the relative offsets may be derived by matching the response with no filters.

    I did that, and came up with a crossover having a beautiful response curve and phase behavior. I built it up, measured the response, and it had a perfect inverse notch at the design axis, which I take to mean that the correct offsets should be derived with the HF polarity inverted.... :p
    I took those individual curves and applied the offsets based on the PCD summed and measured summed response. I set the woofer forward of the tweeter by 60mm and the woofer .125 meter below center and the tweeter .125 meter above center.

    L2 = 4.5mH .3 Ohm
    C2 = 12uF

    C9 = 5.6uF
    R10 = 4.7 Ohm
    R16 = 2.7 Ohm

    The forward lobe looks very good, especially moving toward and above the tweeter position. the overlay is 45 deg above center point.

    R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

    Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51


    95% of Climate Models Agree: The Observations Must be Wrong
    "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

    Comment


    • #32
      Re: Flex Your PCD Mettle:

      Here's the Geddes topology for the equivalent design; we don't know the component values:

      Attached Files

      Comment


      • #33
        Re: Flex Your PCD Mettle:

        Originally posted by Zilch View Post
        Here's the Geddes topology for the equivalent design; we don't know the component values:

        My 5 components looks a little simpler.
        R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

        Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51


        95% of Climate Models Agree: The Observations Must be Wrong
        "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

        Comment


        • #34
          Re: Flex Your PCD Mettle:

          L2 = 4.5mH .3 Ohm
          C2 = 12uF

          C9 = 5.6uF
          R10 = 4.7 Ohm
          R16 = 2.7 Ohm
          Give me a couple of minutes to build it up here.

          [Gotta put some shoes on.... :p ]

          Comment


          • #35
            Re: Flex Your PCD Mettle:

            My 5 components looks a little simpler.

            And it is a most EXCELLENT one; the forward axis is right where we want it to be!

            I'll run the vertical polar map to verify....

            Notes:

            1) HF polarity inverted.

            2) Red = Zilch's design.

            3) Lower L2 to 4.0 mH, maybe?
            Attached Files

            Comment


            • #36
              Re: Flex Your PCD Mettle:

              Originally posted by Zilch View Post

              And it is a most EXCELLENT one; the forward axis is right where we want it to be!

              I'll run the vertical polar map to verify....

              Notes:

              1) HF polarity inverted.

              2) Red = Zilch's design.

              3) Lower L2 to 4.0 mH, maybe?
              It's easy to play with the main inductor value. Smaller will raise the mid levels a bit (less BSC), so blending the tweeter may be necessary. Tweaking the tweeter level is simply a matter of playing around with the shunt resistor. the benefit of keeping it small means that maintaining a first order response to compliment the waveguide is very easy to do with just a single cap. If you lower the inductor to 4mH, raise the shunt resistor to 3 Ohm, maybe 3.3.
              R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

              Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51


              95% of Climate Models Agree: The Observations Must be Wrong
              "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

              Comment


              • #37
                Re: Flex Your PCD Mettle:






                Thank you, Pete; I'm callin' it "Done."
                Attached Files

                Comment


                • #38
                  Re: Flex Your PCD Mettle:

                  Originally posted by Zilch View Post





                  Thank you, Pete; I'm callin' it "Done."
                  I am looking forward to your detailed listening impressions and write up on the cabinet construction.

                  I'm amazed at what 5 components and the right drivers can do.
                  R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

                  Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51


                  95% of Climate Models Agree: The Observations Must be Wrong
                  "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

                  Comment


                  • #39
                    Re: Flex Your PCD Mettle:

                    Originally posted by Zilch View Post
                    Here's the Geddes topology for the equivalent design; we don't know the component values:

                    And when you say Geddes topology for the equivalent design, do you mean the same drivers and waveguide????
                    R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

                    Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51


                    95% of Climate Models Agree: The Observations Must be Wrong
                    "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

                    Comment


                    • #40
                      Re: Flex Your PCD Mettle:

                      That's the crossover for the Geddes Abbey design, which uses the same B&C DE250-8 compression driver on a 12" round Geddes axisymmetric waveguide with B&C 12DBX100 12" woofer. I'm using the KappaLite 3012LF because it can accept a Q=2 assist at 30 Hz to make extended bass in this small cabinet. Used with sub(s) in HT or for SR, they don't need that, of course....

                      Comment


                      • #41
                        Re: Flex Your PCD Mettle:

                        Originally posted by Zilch View Post
                        That's the crossover for the Geddes Abbey design, which uses the same B&C DE250-8 compression driver on a 12" round Geddes axisymmetric waveguide with B&C 12DBX100 12" woofer. I'm using the KappaLite 3012LF because it can accept a Q=2 assist at 30 Hz to make extended bass in this small cabinet. Used with sub(s) in HT or for SR, they don't need that, of course....
                        Geddes sure uses a lot of real estate for a crossover.
                        Click here for Jeff Bagby's Loudspeaker Design Software

                        Comment


                        • #42
                          Re: Flex Your PCD Mettle:

                          I am looking forward to your detailed listening impressions and write up on the cabinet construction.

                          I'm amazed at what 5 components and the right drivers can do.
                          The cabs are here:

                          http://www.parts-express.com/pe/show...number=245-325

                          Your crossover just made these slam-dunk simple to build....

                          Comment


                          • #43
                            Re: Flex Your PCD Mettle:

                            Originally posted by Zilch View Post
                            The cabs are here:

                            http://www.parts-express.com/pe/show...number=245-325

                            Your crossover just made these slam-dunk simple to build....
                            Well how cool is that?

                            Are you adding internal bracing? Damping material? Owens corning 703, 705?
                            R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

                            Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51


                            95% of Climate Models Agree: The Observations Must be Wrong
                            "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

                            Comment


                            • #44
                              Re: Flex Your PCD Mettle:

                              Well how cool is that?

                              Are you adding internal bracing? Damping material? Owens corning 703, 705?
                              They could certainly use a cross brace, tied to the rear panel as well, probably.

                              I just lined the walls with R-13, which adds up to "heavy fill" by some standards. These probably deserve some attention to details by others. I'm vectored toward getting a second one built and running tomorrow.

                              There's two 2" x 10" ports cut in the back with elbows. They run up alongside the woofer magnets inside. I think they're 10", anyway; you can see they're tuned ~30 Hz in the impedance plots. They'd fit on the front baffle, probably, but I want to roundover the woofer opening, so it should be mounted with clamps on the rear, probably. I suppose the clamps could be laid out so as not to interfere with front ports in the lower corners.

                              Comment


                              • #45
                                Re: Flex Your PCD Mettle:

                                Originally posted by Zilch View Post
                                They could certainly use a cross brace, tied to the rear panel as well, probably.

                                I just lined the walls with R-13, which adds up to "heavy fill" by some standards. These probably deserve some attention to details by others. I'm vectored toward getting a second one built and running tomorrow.

                                There's two 2" x 10" ports cut in the back with elbows. They run up alongside the woofer magnets inside. I think they're 10", anyway; you can see they're tuned ~30 Hz in the impedance plots. They'd fit on the front baffle, probably, but I want to roundover the woofer opening, so it should be mounted with clamps on the rear, probably. I suppose the clamps could be laid out so as not to interfere with front ports in the lower corners.
                                I wonder if anyone is bringing an Econowave to InDIYana?
                                R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

                                Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51


                                95% of Climate Models Agree: The Observations Must be Wrong
                                "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

                                Comment

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