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MicroSat design plan - compact 2 way for integration with subwoofer

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  • MicroSat design plan - compact 2 way for integration with subwoofer

    I'm really close to pulling the trigger on these parts and putting this together to mate up with my Indy 8 2.1 powered system project. I thought I'd run the design plan up the proverbial flag pole and see what improvement ideas I could get.

    This will be a build in the Denovo micro knock down cabinets with a response down to about 100Hz where the sub takes over. I've run through a dozen iterations, and am settling on the combination of a DA115-8 woofer and ND16 tweeter. I've chosen to run this sealed, where they roll off a bit shy of the 100Hz target, but the slope is shallow and the combination of room boundary and wall mount will make up for the loss. I also feel the gap is small enough that a stand mount situation would still work acceptably.

    The design is using the Dayton files, ran through response modeler for baffle signature. The crossover is setup to have nearly full BSC, but retain a bit of high frequency rise. I used boundary simulator and blender to get a feel for what the wall mount in my room will do, there will be plenty at 100Hz to meet the sub, but some minor corrections will be required in the 300Hz range to compensate for the walls. I'll do that bit with a little tailored DSP for the room.

    Here's the planned box layout (similar to the Helium):
    Click image for larger version

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    Why didn't I just go with the Helium? - because I don't need bass response, wanted a little higher sensitivity, and an 8 ohm nominal impedance.

    Total cost for the project is $108, and I'm hoping to hit the warehouse sale during MWAF to get that down.
    Electronics engineer, woofer enthusiast, and musician.
    Wogg Music

  • #2
    Here are the crossover and resulting system responses from WinPCD. The phase tracking is quite good, using a guestimated 0.39" z offset for the woofer. That reverse null holds up pretty well +- 1/16", so hopefully I'm close enough.
    Attached Files
    Electronics engineer, woofer enthusiast, and musician.
    Wogg Music

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    • #3
      I have this combo albeit ported in an overnight sensation sized enclosure. Very nice indeed.

      Iirc, your component values are similar to mine as well. Though I think I crossed a bit lower.
      https://www.facebook.com/Mosaic-Audi...7373763888294/

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      • #4
        What are using for the woofer/tweeter acoustic offset in PCD?
        "Everything is nothing without a high sound quality." (Sure Electronics)

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        • #5
          Originally posted by ernperkins View Post
          What are using for the woofer/tweeter acoustic offset in PCD?
          ​X and Y are from the baffle layout, all referenced from the tweeter axis. Woofer x = 0.025m (1") y = -0.070m (2.75"). The guesstimated z was listed above, -0.010m or 0.39"
          Electronics engineer, woofer enthusiast, and musician.
          Wogg Music

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          • #6
            I tried your sim, and made a slight change on your woofer filter to make it match a LR4 at 4k. I did not work out the tweeter filter. For some reason the phase was goofy.
            Attached Files

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            • #7
              Originally posted by rpb View Post
              I tried your sim, and made a slight change on your woofer filter to make it match a LR4 at 4k. I did not work out the tweeter filter. For some reason the phase was goofy.
              Interesting. That does make the woofer rolloff look better, less contribution between 4 and 8k. It does also throw the phase tracking off, so the tweeter needs adjusted to line back up, I'll play with it as another rev.
              Electronics engineer, woofer enthusiast, and musician.
              Wogg Music

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              • #8
                The parts were all purchased from the PE tent sale, I found the DA115's open box in the pile o' stuff and saved a few bucks there too. Haven't even started building and ran into my first design fail.

                Click image for larger version

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                ​The frame of the DA115 is pretty much exactly 4.5", and so is the baffle without the round-over. I've been pondering what to do about it, and figure I'll be cutting my own baffle and using a flush trim bit against the rest of the cab when the time comes. I want a dark, nearly black look, so I'm thinking a poplar 1/2" x 6 board will do for the baffle stock, and I'll do a deep stain and poly on the front with gloss black around the sides. I'll have to make a little jig to do a partial 1/2" roundover around the top and sides of the baffle for a little diffraction reduction and cosmetic cool factor.
                Electronics engineer, woofer enthusiast, and musician.
                Wogg Music

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                • #9
                  You could mount on the backside and make the baffle removable.
                  Kenny

                  http://www.diy-ny.com/
                  DIY NY/NJ 2014 https://www.youtube.com/watch?v=FGwA...ature=youtu.be
                  Man does not live by measurements alone, a little music helps.

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                  • #10
                    Originally posted by kenny_k View Post
                    You could mount on the backside and make the baffle removable.
                    I considered that too, my concern there is the crossover is tweaked for a 0.39" z offset and I would like to avoid adding extra to that. Granted, the crossover is based on manufacturer data so that may end up considerably off anyway, but that's the thought.
                    Electronics engineer, woofer enthusiast, and musician.
                    Wogg Music

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                    • #11
                      You could rear mount the ND 16 with a round over for WG effect. This could keep the appointment offset close.
                      Kenny

                      http://www.diy-ny.com/
                      DIY NY/NJ 2014 https://www.youtube.com/watch?v=FGwA...ature=youtu.be
                      Man does not live by measurements alone, a little music helps.

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                      • #12
                        How could he rear mount the woofers if they are 4.5" OD and his baffle width is 4.5"? That would require side panels that are 0.0" thick.
                        Craig

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                        • #13
                          Originally posted by PWR RYD View Post
                          How could he rear mount the woofers if they are 4.5" OD and his baffle width is 4.5"? That would require side panels that are 0.0" thick.
                          I think he meant use th e back of the box as the baffle, no round over
                          TomZ
                          *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
                          *Part 2 *Gluing multiple curved laminations of HDF *Cello's Speaker Project Page

                          *Building the "Micro-B 2.1 Plate Amplifier -- Part 1 * Part 2 * Part 3 * Part 4 * * Part 5 'Review' * -- Assembly Instructions PDF

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                          • #15
                            Originally posted by tomzarbo View Post
                            I think he meant use th e back of the box as the baffle, no round over TomZ
                            I figured I would have to route an inset for the woofer frame and some gasketing on the back of the baffle. It would work, but would leave a little showing at the edge since there's no clearance. Rear mounting the tweet would help the offset issue. I hesitate to go that route (pun!) Because of the crafty router work to make it happen on a tiny board. I think I can pull off new poplar baffles easier.
                            Electronics engineer, woofer enthusiast, and musician.
                            Wogg Music

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