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  • #31
    I've got an idea that worked on a similar breakup before Tom.

    I have 4 of the woofers in my basket and will place the order when sort out the parts I need to order for my current project.
    Craig

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    • #32
      Originally posted by PWR RYD View Post
      I've got an idea that worked on a similar breakup before Tom.

      I have 4 of the woofers in my basket and will place the order when sort out the parts I need to order for my current project.
      Care to share the trick you used to control breakup?

      Thanks,

      Jason

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      • #33
        Click image for larger version

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        I think I'm happy with how the current crossover looks. I'll post it here for a couple days and see what feedback I get. If all goes well I'll order parts this weekend.

        Right now there is a slight tilt down towards the treble in the overall response. Altering the value for the 4.7 ohm parallel resistor in the tweeter l-pad allows me to adjust that tilt up or down. Values between 3.5 ohms and 5.6 ohms are acceptable without messing up the phase. I'll order a few resistors and experiment.

        Jason

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        • #34
          looking good

          when I put the same FRD / ZMA files that you posted into XSim, I get a different result.

          Look at the freq response here, the phase tracking, and the reverse null -- it doesn't match your post above. And I'm not sure why -- any help?

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          • #35
            also I used the same woofer offset that you mentioned (-0.013 meters = -1.3 cm = -0.52 inches)
            Last edited by ceiol; 03-16-2018, 09:51 PM.

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            • #36
              I get very similar results to yours when I reverse the driver offset in PCD. I'm not familiar enough with Xsim to know how offsets are entered but my guess is it may be the opposite of PCD.

              Jason

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              • #37
                Originally posted by jasonb View Post
                I get very similar results to yours when I reverse the driver offset in PCD. I'm not familiar enough with Xsim to know how offsets are entered but my guess is it may be the opposite of PCD.

                Jason

                you're right -- when I put the woofer offset to +0.50 inches then I get this
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                and if I use +0.75 inches for the woofer offset, then it looks damn-near perfect
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                • #38
                  Originally posted by ceiol View Post


                  you're right -- when I put the woofer offset to +0.50 inches then I get this
                  [ATTACH=CONFIG]n1369378[/ATTACH]






                  and if I use +0.75 inches for the woofer offset, then it looks damn-near perfect
                  [ATTACH=CONFIG]n1369379[/ATTACH]
                  I had a look at Xsim. It looks at offset differently than PCD. PCD takes in to consideration driver offsets in x,y, and z axis. In my design I am using the tweeter axis as a reference and listening distance of 1 meter. I leave all my tweeter offsets at zero. For my woofer I set the Y offset to -0.092 meters since my woofer center is 3.625" below the tweeters, and I set my Z offset to -0.013 meters since my woofers acoustic center (top of voice coil) is approximately 13mm behind the tweeters. PCD views negative offsets as being further away from the listening position. From these numbers PCD calculates the relative distances to the listening position.

                  Xsim only considers the difference in distance to the listening position between the tweeter and woofer. And as we discovered Xsim views positive offsets as being further away from the listening position. If you want to match my simulation you have to manually calculate the difference between the woofer and tweeter. The tweeter is 1 meter (39.37") The woofer needs to be calculated or draw in sketchup and measured. The woofers acoustic center works out to 40.05" from the listening position putting the woofers acoustic center 0.68" further away from the mic than the tweeters. That should get you very close to my result in PCD.

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                  Hope that helps,

                  Jason

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                  • #39
                    makes sense -- thanks for the insight.

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                    • #40
                      Originally posted by jasonb View Post

                      I had a look at Xsim. It looks at offset differently than PCD. PCD takes in to consideration driver offsets in x,y, and z axis. In my design I am using the tweeter axis as a reference and listening distance of 1 meter. I leave all my tweeter offsets at zero. For my woofer I set the Y offset to -0.092 meters since my woofer center is 3.625" below the tweeters, and I set my Z offset to -0.013 meters since my woofers acoustic center (top of voice coil) is approximately 13mm behind the tweeters. PCD views negative offsets as being further away from the listening position. From these numbers PCD calculates the relative distances to the listening position.

                      Xsim only considers the difference in distance to the listening position between the tweeter and woofer. And as we discovered Xsim views positive offsets as being further away from the listening position. If you want to match my simulation you have to manually calculate the difference between the woofer and tweeter. The tweeter is 1 meter (39.37") The woofer needs to be calculated or draw in sketchup and measured. The woofers acoustic center works out to 40.05" from the listening position putting the woofers acoustic center 0.68" further away from the mic than the tweeters. That should get you very close to my result in PCD.


                      Hope that helps,

                      Jason
                      I was having the same problems with my Xsim not matching PCD - changed the offsets around and now they are very close. Thanks for the tip

                      Has anyone got their drivers yet and done some Dats sweeps? Mine should be here today hopefully.
                      See my projects on Instagram and Facebook

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                      • #41
                        The UPS tracking says mine are on the truck and out for delivery today! I might have a chance to flex them a little and measure with my WT3 after work.
                        Craig

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                        • #42
                          jasonb -- I now see the wisdom of your tweeter choice: the physical dimensions / cut out size of the ND28 is basically identical with the ND20F-4 that comes in the KM402 speakers.

                          These ND28s will drop right in. Just buy the MK402s, replace the tweeters and the XO circuits and you're done!

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                          • #43
                            Originally posted by PWR RYD View Post
                            The UPS tracking says mine are on the truck and out for delivery today! I might have a chance to flex them a little and measure with my WT3 after work.

                            Craig - I'm curious to see what the measured T/S parameters are for these. My attempt at pairing them with the new ND140PR is a flop - evidence that I don't yet understand how to use passive radiators. But the pairing with the BC25SC06 seems to work well. I'll build some new boxes this weekend and go back to working with ports.
                            Co-conspirator in the development of the "CR Gnarly Fidelity Reduction Unit" - Registered Trademark, Patent Pending.

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                            • #44
                              Hi Tom,
                              I received my four drivers the other night. I broke them in and took T/S measurements. Two of the four measured identical to each other and very close to Dayton's specs. The other two had issues and measurements were way off. But as usual PE to the rescue, they are sending me two new drivers. I'll post my measurements when I get some time.
                              Craig

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                              • #45
                                I have all my parts on order. Should be here next week. Then I can get a test enclosure and crossover built and see how it sounds.

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