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  • Re: Flex Your PCD Mettle:

    Originally posted by stgdz View Post
    ok for the sake of exercise I am trying to learn this program and by doing that I am entering the data into PCD using to see if I understand it correctly.

    Anways, I using this crossover


    but when I go to input stuff, I can input all of the data for the woofer but I get confused on how to input the tweeter. I looked at the filter layouts in the tab but I couldn't figure out where R2 is entered. I have attached all my data entry's. When I run this data though I get a huge drop at around 1600hz.
    Nope, not quite.

    First, remove L3 and add it to the section where you have 6 Ohm and 125uF. That will take care of the parallel trap.



    To model R2, you have to "fake out" PCD just a bit. Add the last two components to the tweeter XO section, C10 and L10, but set C10 to a HUGE value, like 9999999999999, and set L10 to zero and it's series resistance to the value of R2.

    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:

      Ok I got everything all correct now, I put in all the stuff for the crossovers. I still had a huge null in the middle of the crossover so i change both z-values(woof and tweet) to zero.

      That removed the null. So any little front to back change can have a huge effect on the over all performance of the system then huh?
      My simple speaker project
      My simple subwoofer project

      The Inlaws Hometheater

      Comment


      • Re: Flex Your PCD Mettle:

        Regarding the null, that was probably due to the tweeter polarity. The schematic shown reverse polarity, your model looks like it was set to normal. Toggle it and see if your null comes back.

        Yes, moving the drivers front/back (z-axis) has an impact on the phase relationship at the XO frequency. Going back and forth betweent the model and the measured response (max null) is how you determine the acoustic offset distance (similar to physical offset distance).

        Comment


        • Re: Flex Your PCD Mettle:

          so now that I am starting to learn the stuff with PCD, and starting to learn other things about crossovers and drivers.

          How can I tell if drivers are in phase with each other? Do the drivers and the total phase have to line up with each other?



          I should preface that I have a econo wave seven SR build that I was going to do, I didn't take measurements correctly and am down to an SR LCR build. Well the men in my head looked at all the left over drivers and said, hey why not build a dual woofer setup. I have been looking at the Zilch notes on JBL FAT and it appears he tricked PCD by doing a three way and then using the woofers and a woofer and midrange setup.



          yeah I am going off the deep end with this.


          OK so here is what I have, I modeled up a three way with the PA 310-8 as the midrange. The woofer region I tried to leave some of the existing crossover components in there so this is is what is in there but I took out the series section after the crossover and the midrange I just had PCD auto calculate the values for a third order parallel and then looked at the PE parts inventory and used the values closet to what was in PCD. For the 220ti I ended up removing the after series section of the crossover as it ended up gaining a couple of dB, the 220ti still rolls off at 6k though(slightly) though.


          I have attached all my hacks but what did I do wrong with this?
          Attached Files
          Last edited by stgdz; 03-11-2011, 02:13 AM.
          My simple speaker project
          My simple subwoofer project

          The Inlaws Hometheater

          Comment


          • Re: Flex Your PCD Mettle:

            Where can I get the waveguide to build the SR'S?

            Comment


            • Re: Flex Your PCD Mettle:

              Originally posted by giverago View Post
              Where can I get the waveguide to build the SR'S?
              You can't, unless you have a serial # for the HPR152i all points are cut off. There is no way to get them, QSC has shut it down and PE can't get the design rights to them.

              Do like I do and just build it with the regular econowave waveguide.


              I have a question though on the SR crossover

              Is the polarity reversed in this crossover for the tweeter?
              My simple speaker project
              My simple subwoofer project

              The Inlaws Hometheater

              Comment


              • Re: Flex Your PCD Mettle:

                Originally posted by stgdz View Post
                I have a question though on the SR crossover

                Is the polarity reversed in this crossover for the tweeter?
                It certainly looks that way from the posted schematic.
                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:

                  psssst. badges: http://www.audiokarma.org/forums/sho...ostcount=12937

                  ;)

                  Comment


                  • Re: Flex Your PCD Mettle:

                    It certainly looks that way from the posted schematic.
                    so in post 1230 http://techtalk.parts-express.com/sh...postcount=1230 I didn't reverse the polarity.


                    did I miss something with the crossover because when I go back and reverse the polarity it messes up all the phases.
                    My simple speaker project
                    My simple subwoofer project

                    The Inlaws Hometheater

                    Comment


                    • Re: Flex Your PCD Mettle:

                      Originally posted by stgdz View Post
                      so in post 1230 http://techtalk.parts-express.com/sh...postcount=1230 I didn't reverse the polarity.


                      did I miss something with the crossover because when I go back and reverse the polarity it messes up all the phases.
                      Double check all your Z offsets. Either the woofer is behind the tweeter or in front, but one of them needs to be the 0 reference. You've got the tweeter offset by a HUGE amount.
                      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


                      • Precursor to eConowave - need crossover design input

                        Hi Guys,

                        Back in 2008, Zilch and I built this set of speakers using these components and an active crossover:

                        Cabinet volume = 1.43 ft3

                        AK build thread:http://audiokarma.org/forums/showthread.php?t=160792
                        Quoting Zilch
                        "Horns: JBL PT-D95HF. Score the Masonite so they mount flush from the front.

                        http://audiokarma.org/forums/attachm...2&d=1208200912

                        Drivers: BMS 4555

                        http://www.bmspro.info/index.php?sho...10280&id=54366

                        Woofers: JBL 127H-1 off eBay, rear mounted like the Jensens.

                        Ports: MAY fit through the front. Provide interior dimensions for modeling and calculation.

                        Crossover: 1.8 kHz active, Behringer CX3400 with simple compensation filter. I haven't designed a passive for these yet."


                        I touched bases with Zilch a number of times over the last few years on designing a passive crossover, but we never got around to it.

                        The speakers sound great biamped using a Behringer CX3400, with one exception, a high noise floor in both the compression drivers and the woofers. I bought another CX3400 and it has the same issue. All my trouble shooting indicates the crossover is the issue (and I've done a lot of TS).

                        So, my question is would any of the eConowave cross over variants work for this BMS and JBL combo that are posted here on AK or on the Parts Express Tech Talk forum? What do you guys think?

                        The Altec 414Z project used the BMS 4555 HF driver. What might need to be changed in this crossover to facilitate the JBL 127H-1 woofer I used?

                        Thanks,
                        Scott
                        Attached Files

                        Comment


                        • Re: Precursor to eConowave - need crossover design input

                          Originally posted by BmWr75 View Post

                          The speakers sound great biamped using a Behringer CX3400, with one exception, a high noise floor in both the compression drivers and the woofers. I bought another CX3400 and it has the same issue. All my trouble shooting indicates the crossover is the issue (and I've done a lot of TS).



                          Thanks,
                          Scott
                          I don't know anything about passive crossovers but I have run an active system using a Behringer DCX-2496. I didn't have any noise. Well, a tiny bit of hiss from the horns but had to turn it up and put my ear next to one to hear it.

                          Comment


                          • Re: Flex Your PCD Mettle:

                            You are the second person that has told me the DCX2496 is very quiet. May have to check one of those out.

                            Comment


                            • Re: Flex Your PCD Mettle:

                              Originally posted by stgdz View Post
                              You can't, unless you have a serial # for the HPR152i all points are cut off. There is no way to get them, QSC has shut it down and PE can't get the design rights to them.

                              Do like I do and just build it with the regular econowave waveguide.


                              I have a question though on the SR crossover

                              Is the polarity reversed in this crossover for the tweeter?
                              Do I use the SR's crossover still if I use the regular econowave waveguide?

                              Comment


                              • Re: Flex Your PCD Mettle:

                                I've found the dbx active crossovers (223 actually) to be quieter than the Behringer CX2310 I had. The Behringer made noticeable hiss. I also have a DCX2496 and I don't believe it is in any way silent.
                                ~Brandon

                                Soma Sonus
                                DriverVault

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