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InDIYana 2020 theme build - The Portals

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  • #16
    Originally posted by Kevin K. View Post
    Very cool concept! Are you anticipating some cancellation or is there a way around it with this design? Looking forward to the measurements.
    There should be a whole lot of cancellation, but I'm hoping since I'll be starting at 90 degrees off axis from the individual drivers and that there are so many of them, the cancellation will be predictable and manageable in the xo.
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    • #17
      I still think 2 faceless in a pipe cylinder, with mount as you describe could work, and match your bipolar response.
      Wolf
      "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
      "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
      "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
      "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

      *InDIYana event website*

      Photobucket pages:
      http://photobucket.com/Wolf-Speakers_and_more

      My blog/writeups/thoughts here at PE:
      http://techtalk.parts-express.com/blog.php?u=4102

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      • #18
        Very very cool. Dan. Wish I had thought of that approach. Reminds me a bit of the way I did the tweeters in the Contrapesso's, at least from a bipole response from a centered driver(s). In fact, that type of tweeter arrangement might work very well with this mid arrangement, both being bipole and the tubes also giving the benefit of waveguide boost. It will be interesting to see how the measurements look.

        Personally, I wouldn't frett too much about cancellation and instead focus on power response. Measure as far away as you can get away with to reduce the impact that close mic'd cancellations may show. Use that for initial crossover design, but after that maybe use an RTA type, ungated measurements, while moving your mic in about a 3' cube with your averaging set to continuous or forever, so you get a continuous averaging of the response over time and over a larger space.

        You may actually not get too much cancellation until you reach a point where the drivers are beaming enough that reflections off the opposite sides are reflecting back. Until that point, I would think they would sum as if they are one driver located in the center of the array.

        At any rate, can't wait to see what you encounter and how you proceed!

        I'm glad you started a thread here. I like the Facebook group, but it doesn't work all that well to follow a consistent thread over time. There is a lot everyone could learn from what you are doing here.
        Dan N.

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        • #19
          Marv- They are 3D printed.
          Wolf
          "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
          "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
          "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
          "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

          *InDIYana event website*

          Photobucket pages:
          http://photobucket.com/Wolf-Speakers_and_more

          My blog/writeups/thoughts here at PE:
          http://techtalk.parts-express.com/blog.php?u=4102

          Comment


          • #20
            Originally posted by dlneubec View Post
            Very very cool. Dan. Wish I had thought of that approach. Reminds me a bit of the way I did the tweeters in the Contrapesso's, at least from a bipole response from a centered driver(s). In fact, that type of tweeter arrangement might work very well with this mid arrangement, both being bipole and the tubes also giving the benefit of waveguide boost. It will be interesting to see how the measurements look.

            Personally, I wouldn't frett too much about cancellation and instead focus on power response. Measure as far away as you can get away with to reduce the impact that close mic'd cancellations may show. Use that for initial crossover design, but after that maybe use an RTA type, ungated measurements, while moving your mic in about a 3' cube with your averaging set to continuous or forever, so you get a continuous averaging of the response over time and over a larger space.

            You may actually not get too much cancellation until you reach a point where the drivers are beaming enough that reflections off the opposite sides are reflecting back. Until that point, I would think they would sum as if they are one driver located in the center of the array.

            At any rate, can't wait to see what you encounter and how you proceed!

            I'm glad you started a thread here. I like the Facebook group, but it doesn't work all that well to follow a consistent thread over time. There is a lot everyone could learn from what you are doing here.
            I'm of the same mind as you that I'm going to get some decent summing especially in the far-field, but we'll see. This version will use the standard forward facing tweeter, but if the woofers play nice, I'd like to experiment with some alternate tweeter loadings. Your Contrapessos have always been one of my favorite designs, btw, and one that has inspired me to do funky stuff like this. There were so many oddball elements to that design and it all came together and sounded remarkably cohesive.
            _____________________________
            Tall Boys
            NRNP Computer Sub
            The Boxers
            The Hurricanes
            The Baronettes
            Conneccentric
            UX3

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            • #21
              I think we, as DIY speaker designers, tend to dismiss array approaches due to the perceived negatives of "cancellations" or "comb filtering" etc. I read a lot of knee-jerk negative responses to any proposed array-type solutions all the time in forums. I would suggest that it may not matter much when listening far field in real room conditions, despite what our near field or gated measurements may indicate. The benefits of multiple arrayed drivers may outweigh the negatives.
              Dan N.

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              • #22
                Got the cabs painted, woofers installed and took some preliminary measurements of the woofers only. Measurements were taken indoors, on axis at 1m from the front of the baffle. I think with this setup, I really need to take measurements outdoors at 2m+ to get a better representation of the summing that occurs, but there are definitely some trends here. It doesn't sound as ragged as it looks, but the large peak around 400Hz is audibly imbalanced. I'll play around removing this with a parallel LCR circuit before rolling off, probably with a single inductor around 2kHz.
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                • #23
                  OK, you have me baffled (pun intended). Where does the tweeter go? At first I thought it would be on the short face and the hole would face left/right. But then I thought a Dan N. tweeter on top would work too, with the hole facing you. The suspense is killing me.

                  -Bob
                  -Bob

                  The PEDS 2.1 mini system
                  My A7 Project - another small desktop speaker
                  The B3 Hybrid Dipole - thread incomplete and outdated

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                  • #24
                    Originally posted by BOBinGA View Post
                    OK, you have me baffled (pun intended). Where does the tweeter go? At first I thought it would be on the short face and the hole would face left/right. But then I thought a Dan N. tweeter on top would work too, with the hole facing you. The suspense is killing me.

                    -Bob
                    The tweeter will be suspended in the middle of the opening, facing forward.
                    _____________________________
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                    Conneccentric
                    UX3

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                    • #25
                      DSP to the rescue! Joking and realize this will have to be passive for the contest. But it sure looks tempting to throw a few PEQ adjustments at it. Bass response looks pretty good, how far from the wall was it when you took the measurements?
                      My "No-Name" CC Speaker
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                      • #26
                        I wonder how differently they would perform if you deployed the drivers pointing outward around the perimeter of a round (or diamond shaped) enclosure? I look forward to see/hear them. Hopefully InDIYana will occur at some point...

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                        • #27
                          Originally posted by DanP View Post

                          The tweeter will be suspended in the middle of the opening, facing forward.
                          That may have a significant effect on the woofer response. Could be a good or bad thing. Can't wait to see how you plan to mount it. I think I know what might work best and you could most certainly create it with your printing capability.
                          Dan N.

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                          • #28
                            Originally posted by Kevin K. View Post
                            DSP to the rescue! Joking and realize this will have to be passive for the contest. But it sure looks tempting to throw a few PEQ adjustments at it. Bass response looks pretty good, how far from the wall was it when you took the measurements?
                            It was out in the middle of the room and the ports on the bottom were blocked. I let it rip a little and bass will not be an issue with these speakers 😁. I don't think going passive will be much of an issue either. I'll need a notch filter, but after that, the lowpass should be pretty straightforward.
                            _____________________________
                            Tall Boys
                            NRNP Computer Sub
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                            • #29
                              Originally posted by dlneubec View Post

                              That may have a significant effect on the woofer response. Could be a good or bad thing. Can't wait to see how you plan to mount it. I think I know what might work best and you could most certainly create it with your printing capability.
                              I'm still not 100% on the details, but I'll have some geometry extending from the back of the cabinet in through the opening and my plan is to make it as svelte as possible. 3D printing is my preferred method, just haven't found the right geometry.
                              _____________________________
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                              NRNP Computer Sub
                              The Boxers
                              The Hurricanes
                              The Baronettes
                              Conneccentric
                              UX3

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                              • #30
                                I think I get it now that's where your head goes? LOL Wish I didn't live so far away !

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