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Flex Your PCD Mettle:

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  • Re: Flex Your PCD Mettle:

    Yes, I had settled on the Deltalite 2512, but then I thought it would be fun to see if an LA would work w/ this awesome QSC/250 combo, esp since my LR are 1-way full range LAs, and w/ the sub, and bringing the WG up to a good height.
    The 2512 models to a 2.27cf box, so if I went that route I could gain some height there, esp w/ a trap shaped box.
    If I wanted to try the EconoWave LA as a learning experience, could you guys help me properly measure the result so I can see if it worked, beyond just hearing it?
    Thought the array could be 8 of these which match my MCLA LRs, albeit 6" vs 4" - http://www.parts-express.com/pe/show...number=295-342

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    • Re: Flex Your PCD Mettle:

      A line array cannot achieve the constant directivity and controlled dispersion that this project aims for without being pretty different from this project.
      Last edited by dtruck; 01-30-2012, 01:03 PM. Reason: forgot a word

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      • Re: Flex Your PCD Mettle:

        OK - thanks - I won't waste time and $ on it then. Will go w/ the Deltalite 2512 way! Is the only reason to use the Kappalite instead to pick up more lowend? Is the Deltalite idea to give better mid-lows? Since I have the THT sub, I just want the best sound for the center channel, whether that be the Kappa or Delta.
        Will be building my own cab, so is there any downside to building as a 2.27 cf as the driver actually specs to as opposed to the 1.5 that the Trap PA prebuilt is?
        As long as I maintain the proper driver spacing and the baffle width?
        Is the baffle width actually 17" outside width(including the joints w/ the side panels) on the pre-cut PA box?
        I was planning to flush mount the baffle and round-over the edges if acoustically a good idea.
        So I was thinking a 2 cf trap shaped sealed box, stuffed to make it "seem" 2.27 cf, w/ the drivers near the top, properly CTC spaced. Any problems?

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        • Re: Flex Your PCD Mettle:

          In a larger box, and the Deltalite 2512 concept, is there any place for a 12" passive radiator, or would that mess w/ directivity?

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          • Re: Flex Your PCD Mettle:

            Mine are in 2 cuft sealed boxes and extend easily flat to 80hz in room with no need for a high pass filter. I only low pass the bass bins for a seedless match......Geddes does the same but instead uses band pass subs for an all acoustic low pass approach.

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            • Re: Flex Your PCD Mettle:

              Ordering my 12" driver for the Deltalite plan and came across this other Eminence driver - aside from weight is this not a better FR curve? Cost about the same.
              http://www.parts-express.com/pdf/290-593s.pdf
              http://www.parts-express.com/pdf/290-510s.pdf

              And, I am aware that the baffle is 17" wide because that is how the Trap PA comes, but if one is building their own box is there an acoustic reason not to narrow that down to 15 and round over the edges? Sealed box, ~ 2cf.

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              • Re: Flex Your PCD Mettle:

                Originally posted by gmannel View Post
                Ordering my 12" driver for the Deltalite plan and came across this other Eminence driver - aside from weight is this not a better FR curve? Cost about the same.
                http://www.parts-express.com/pdf/290-593s.pdf
                http://www.parts-express.com/pdf/290-510s.pdf

                And, I am aware that the baffle is 17" wide because that is how the Trap PA comes, but if one is building their own box is there an acoustic reason not to narrow that down to 15 and round over the edges? Sealed box, ~ 2cf.
                The 2512/DE250/QSC152i combo has the crossover already worked up. Change the woofer and you need to change the crossover. I would stick with the 2512 if the cost difference isn't an issue.

                Changing the baffle width from 17" to 15" will have some effect on the system response. Will it be enough to matter? I don't know. I doubt it would be huge.

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                • Re: Flex Your PCD Mettle:

                  I could do the already designed passive xover, but I was planning to bi-amp and use a miniDSP. I felt like since I was not using the exact cabinet in the plans the designed crossover might need some changes, and my newby understanding is that active is easier to tweak. The speaker(as a vertical center behind the screen) was maybe going to be taller as a sealed 2cf trap box to get to better listening height. Driver spacing as per plans. Do you see any issues?

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                  • Re: Flex Your PCD Mettle:

                    You should be fine with that and the MiniDSP, provided you have a way to measure and see what you're getting. By ear alone you'll never know whether you have the match at the crossover region right. Delay in the MiniDSP helps out on that a lot, adding delay in a passive can be trouble.
                    Free & Free-form simulator/designer for Passive Crossovers
                    SynergyCalc 5: design spreadsheet for Wooden horns and DIY Synergy Waveguides
                    Super easy and cheap to make high performance sound diffusers

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                    • Re: Flex Your PCD Mettle:

                      Yes, I will be measuring, have a NIB CS calibrated Dayton mic and a NIB Tascam 124MkII 'sound card'( with not a clue yet as what to do w/ them)

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                      • Re: Flex Your PCD Mettle:

                        Originally posted by gmannel View Post
                        Ordering my 12" driver for the Deltalite plan and came across this other Eminence driver - aside from weight is this not a better FR curve? Cost about the same.
                        http://www.parts-express.com/pdf/290-593s.pdf
                        http://www.parts-express.com/pdf/290-510s.pdf

                        And, I am aware that the baffle is 17" wide because that is how the Trap PA comes, but if one is building their own box is there an acoustic reason not to narrow that down to 15 and round over the edges? Sealed box, ~ 2cf.
                        Note the resonant freq of the Deltalight.....much lower than the pro and I wouldn't even think about trusting Eminence measurements. If you can find reliable 3rd party measurements of the Delta Pro to compare then they might be worth the effort.

                        As to the baffle width, reducing it will alter the original designs baffle step compensation slightly. I doubt you'll hear a difference but I don't understand why you can't maintain the designed width and still maintain the recommended box volume by simply altering the enclosure depth.

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                        • Re: Flex Your PCD Mettle:

                          So the lower resonant freq should steer me toward the Deltalite? As I said, price is essen the same, it was just the flatter FR that piqued my interest.
                          As to the baffle width, 17 is fine, I was just trying to learn if 17 was chosen for any acoustic reason, or just because the prebuilt box came that way. Since I'm building from scratch it matters not, so if it wasn't detrimental acoustically I thought to model the dimensions of the box to their most ideal config.

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                          • Re: Flex Your PCD Mettle:

                            Originally posted by gmannel View Post
                            So the lower resonant freq should steer me toward the Deltalite? As I said, price is essen the same, it was just the flatter FR that piqued my interest.
                            As to the baffle width, 17 is fine, I was just trying to learn if 17 was chosen for any acoustic reason, or just because the prebuilt box came that way. Since I'm building from scratch it matters not, so if it wasn't detrimental acoustically I thought to model the dimensions of the box to their most ideal config.
                            The XO was originally created in that size box so there is a relationship to the final voicing and BSC.

                            Generally the lower Fs idicates that the driver will extend lower. My experience with the 2512 has shown it to be true in this case. Good luck with your build!

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                            • Re: Flex Your PCD Mettle:

                              @gmannel

                              Note that Edlafontaine and i had the same issues with mids using Deltalite II 2512. There is a solution but i haven't measured fr to se if it is linear enough, yet. That xover is done only by using PCD.

                              Please read this stuff:

                              http://www.audiokarma.org/forums/sho...ostcount=13885

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                              • Re: Flex Your PCD Mettle:

                                Got my drivers! BC250, QSC, 2512, and my miniDSP.
                                Box will be scratch built. Size is not a consideration as will be behind a screen.
                                In general, for an Ewave, what would lead one to choose, or reject:
                                1) Sealed
                                Smaller size? Any acoustic advantage?
                                2) Vented
                                Better efficiency? Bass extension?(less important as already have TubaHT)
                                3) Passive radiator
                                Would this have a detrimental effect on the constant directivity goal?

                                And finally, if I model the 2512 using TS parameters, etc, rec.box size is 2.37 cf. Manufac spec sheet says 0.8!! What do I believe? That's a huge difference!

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