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Flex Your PCD Mettle:

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  • Re: Flex Your PCD Mettle:

    Originally posted by djg View Post
    Very OT, family vacation with parents at Carolina Beach. What a beautiful spot.

    Travis, have you been to AVSforum DIY speaker subforum? Very many people there with similar interests. Check it out.
    And I was in Wisconsin last month
    I have been there, but just registered... I figured here would be better since this idea is sort of based on a Ewave. But I'll start a thread there.

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    • Re: Flex Your PCD Mettle:

      Does anyone know anyone near Wilmington, NC that is a Pro Audio DIY hobbyist/expert?
      He's not in Wilmington...a little further up-country, I believe. Michael Mardis, aka Pano @ diyaudio

      http://www.diyaudio.com/forums/members/pano.html
      Mongo only pawn in game of life
      ____
      Ed

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      • Re: Flex Your PCD Mettle:

        Anyone use the knock down birch cabinets to build an econowave build? I am just wondering if the sizes work.

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        • Re: Flex Your PCD Mettle:

          Sizing depends on your woofer choice, the F3 you want and the waveguide you've chosen. Easy enough to figure out.


          Originally posted by JoshK View Post
          Anyone use the knock down birch cabinets to build an econowave build? I am just wondering if the sizes work.
          I was so much older then, I'm younger than that now.
          OS MTMs http://techtalk.parts-express.com/sh...d.php?t=220388
          Swope TM http://techtalk.parts-express.com/sh...d.php?t=221818
          Econowave and Audio Nirvana AN10 fullrange http://techtalk.parts-express.com/sh...d.php?t=216841
          Imperial Russian Stouts http://techtalk.parts-express.com/sh...=1#post1840444
          LECBOS. http://techtalk.parts-express.com/sh...ghlight=lecbos

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            • Re: Flex Your PCD Mettle:

              Originally posted by Mayhem13 View Post
              Yeah but it's long been my contention that you need a 1.4" CD or larger to play to 700hz nicely and now the +10hz content suffers on both FR and directivity still leaning towards a three way only now with a super tweeter of sorts. Not a bad thing, but still a 3way. Better to fatten up the bottom IMO.
              They make a 1", 1.4" and 2" version, I don't recall there being much of a difference between them...

              रेतुर्न तो थे स्रोत
              return to the source
              leviathan system thread
              deadhorse thread
              shockwave build thread

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              • Re: Flex Your PCD Mettle:

                Hey guys. I have some questions (maby dumb ones) so please shut me up when you think that i'm babbling :D

                I've been playing with PCD some more. Zilch (thanks again big guy) gave measurements details for Delite as .FRD and .ZMA for it in this post:

                http://techtalk.parts-express.com/sh...&postcount=136

                I tryed to find the acoustic offsets for Deltalite and B&C DE250-8 in PCD using guide in PDF from Jeff Bagby (to who i dont know how to thank enough for everything he did for DIY community).

                My question is this... Since Deltalite II 2512 is aproximetly same depth and size like Kappalite 3012 i entered same distance (-0.065m) at Z axis in PCD but came up with nothing. Then i tried to find it myself like the guide said and this is with what i came up with:

                .FRD and .ZMA imported in PCD and then adjusted measuring distance (47") and vertical offsets (10.5"):

                http://img13.imageshack.us/img13/408...maimported.jpg

                This is acoustic offset at Z axis that gave me identical response:

                http://img403.imageshack.us/img403/9...tersdeadon.jpg

                Could this be true or am i doing something wrong here ? Acoustic offset which shows that Deltalites acoustic center is 11cm (4.33") behind (further from the listener) from the QSC B&C DE250-8 ? Physically the diference is almost the same like with Deluxe.
                Last edited by Zvuchniak; 12-24-2011, 09:46 AM.

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                • Re: Flex Your PCD Mettle:

                  Originally posted by Zvuchniak View Post
                  Hey guys. I have some questions (maby dumb ones) so please shut me up when you think that i'm babbling :D

                  I've been playing with PCD some more. Zilch (thanks again big guy) gave measurements details for Delite as .FRD and .ZMA for it in this post:

                  http://techtalk.parts-express.com/sh...&postcount=136

                  I tryed to find the acoustic offsets for Deltalite and B&C DE250-8 in PCD using guide in PDF from Jeff Bagby (to who i dont know how to thank enough for everything he did for DIY community).

                  My question is this... Since Deltalite II 2512 is aproximetly same depth and size like Kappalite 3012 i entered same distance (-0.065m) at Z axis in PCD but came up with nothing. Then i tried to find it myself like the guide said and this is with what i came up with:

                  .FRD and .ZMA imported in PCD and then adjusted measuring distance (47") and vertical offsets (10.5"):

                  http://img13.imageshack.us/img13/408...maimported.jpg

                  This is acoustic offset at Z axis that gave me identical response:

                  http://img403.imageshack.us/img403/9...tersdeadon.jpg

                  Could this be true or am i doing something wrong here ? Acoustic offset which shows that Deltalites acoustic center is 11cm (4.33") behind (further from the listener) from the QSC B&C DE250-8 ? Physically the diference is almost the same like with Deluxe.
                  Set your woofer Y offset to -.133. It's below the mic, and without the sign, you have it coincident with the tweeter. Won't make any difference to the acoustic offset calculation though.

                  Actually, the tweeter is further behind the woofer, since the woofer offset is positive. Click on the Driver Z Offset cell, and a pop up will explain the polarity.

                  To get that 2-way right, you have to invert the tweeter polarity.

                  I just ran a sim.

                  Woofer: 3mH series, shunt 15uF, series .5mH to woofer +

                  Tweeter: 5 Ohm in series with 6.8uF, shunt .3mH in series with 4 Ohm, series 15uF to tweeter -, and 6.2 Ohm across tweeter terminals.

                  Gives a nice response to start tweaking.
                  Attached Files
                  Last edited by Pete Schumacher; 12-24-2011, 07:06 PM. Reason: Corrected tweeter wiring polarity
                  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.

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                  • Re: Flex Your PCD Mettle:

                    Actually, the tweeter is further behind the woofer, since the woofer offset is positive. Click on the Driver Z Offset cell, and a pop up will explain the polarity.
                    But the instructions page in PCD says this:

                    For the Z-Offset; farther back, like with a woofer's voice coil is a positive value, since it is added to the listening distance. A negative value here would be subtracted to indicate that the driver's acoustic center is closer to the listening point.

                    Woofers Y offset is -0,133 and for tweeter is 0,133 as can be seen on the image:



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                    • Re: Flex Your PCD Mettle:

                      Now, if negative value on Z axis means that acoustic center is closer to the listener (subtratcs distance), and positive value means that acoustic center is farther from the listener (adds distance), can we conclude that acoustic center of Deltalite is 11cm farther from the B&C DE250-8 despite the waveguide physical depth ?

                      In that case, midbass mounting on the back side of the front pannel would be unwanted because of adding more distance unnecessarily. The next image shows that acoustic offset is frequency dependent (taken from Loudspeaker Design Cookbook):

                      Comment


                      • Re: Flex Your PCD Mettle:

                        I just had this exact same conversation with Jeff.

                        That part of the instruction page needs an update, and I think you can actually make it yourself.

                        If you go to the end where important updates are mentioned, he notes the change to polarity that's reflected in the pop-up. It's all handled in the equations behind the calculations. The sign of the offset is set in the background.

                        And I've corrected the polarity of the tweeter wiring in my previous post. The large offset of the woofer ahead of the tweeter requires the tweeter to be reverse polarity and sum like it did in the sim.

                        All of this can be modified, by mounting the woofer to the back side of a 1.5" thick baffle with big roundovers or chamfers, pushing the woofer back closer to the tweeter acoustic center.

                        This is one reason why a stand mount Econowave might not be the best option. Leave it on the floor with the tweeter above the woofer, and the relative acoustic offset changes to your benefit at the listening position. Everything depends on your target listening axis, and you can actually pick that based on the acoustic offset you have measured from the position you did.
                        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


                        • Re: Flex Your PCD Mettle:

                          I just had this exact same If you go to the end where important updates are mentioned, he notes the change to polarity that's reflected in the pop-up. It's all handled in the equations behind the calculations. The sign of the offset is set in the background.

                          And I've corrected the polarity of the tweeter wiring in my previous post. The large offset of the woofer ahead of the tweeter requires the tweeter to be reverse polarity and sum like it did in the sim.
                          If i just reverse + and - on the tweeter polarity button will it work fine ?

                          Thanks in advance Pete

                          Comment


                          • Re: Flex Your PCD Mettle:

                            Originally posted by Zvuchniak View Post
                            If i just reverse + and - on the tweeter polarity button will it work fine ?

                            Thanks in advance Pete
                            Only when you want to make a system with the listening axis straight ahead, and the woofer mounted that far forward of the tweeter.

                            For calculating acoustic offset, you leave the tweeter polarity positive, just like you did. That calculation is about a perfect a match as you could have hoped for.

                            In order to do the crossover I did, for a listening axis in between the woofer and tweeter, you need to reverse the tweeter polarity to get good summation at the crossover point for 4th order slopes.

                            If you start moving the woofer back toward the tweeter, you will find that it will revert back to positive polarity when acoustic centers are lined up.
                            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


                            • Re: Flex Your PCD Mettle:

                              Only when you want to make a system with the listening axis straight ahead, and the woofer mounted that far forward of the tweeter.
                              That FRD and ZMA files are from econowave delite so we are talking about the design that is already done. Measurement provided by Zilch.

                              So it is not the question of what i want. It is more about what should we do in case that you can't change the speaker cabinet. What you see is what you get

                              Comment


                              • Re: Flex Your PCD Mettle:

                                I haven't read this whole thread or the AK one either. I did see Fastbike's standard Econowaves in old Radio Shack cabs, and I liked that project. I just procured a pair of remarkably nice Pioneer cabs from the 70s. About 1.7 cu. ft., 3/4" particle board, they even have a brace and carpet padding inside. I will be ordering parts shortly.

                                I have a question for the experienced Econowavers. Do you leave these on the floor, or raise them up a bit, and tilt them back perhaps on stands?

                                I will post a few construction pics soon.

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