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NE225W+PM180+ViaWave Design & Build Thread

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  • #76
    Originally posted by jonasz View Post
    Is the Viawave comfortable with a 2k crossover?
    All depends on how you work the tail. All ribbon tweeters have chamber/foil resonance that falls between 1500hz and 1800hz. It's sort of like Excel Magnesium breakup. Viawave is no exception in this respect.
    This resonance or the luck of attenuation on the part of many designers gives ribbons bad rep BTW. If you notch it out and your main electrical filter brings the tail sufficient enough, I can see 2.2khz safely and clean.
    http://www.diy-ny.com/

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    • #77
      Originally posted by r-carpenter View Post

      All depends on how you work the tail. All ribbon tweeters have chamber/foil resonance that falls between 1500hz and 1800hz. It's sort of like Excel Magnesium breakup. Viawave is no exception in this respect.
      This resonance or the luck of attenuation on the part of many designers gives ribbons bad rep BTW. If you notch it out and your main electrical filter brings the tail sufficient enough, I can see 2.2khz safely and clean.
      Thanks Roman.
      Maybe, just maybe, they can be paired with the Excel W15 then but it will probably be a stretch... Sorry for th OT
      "It is only Scrooge McDuck and others with a personality disorder who have money as their goal"

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      • #78
        jml- I feel that there are good points in all 3 of your sims, but I feel that you aren't where you should be yet.
        In the first, you likely have the sum of MT a bit higher than necessary to sum flat, but it's in a better range. resonance of filter parts is likely the cause of the impedance dip.
        In the second, I agree that the tweeter is going to low.
        3rd has good impedance.

        Some thoughts- I think you'll likely find better summations in the 300-500Hz range for woofer to midrange, 2.5-3k for midrange to tweeter, and I'd try and allow the drivers to show you where they want to xover. Don't try and force them to do one thing or another. I know Pete said that the PM midbasses typically use an order higher slope to get one less order rolloff, and to use a damping resistor to complement the cap in the circuit. ie- use a damped 3rd order LP (coil-shunt CR-coil) to yield a 2nd order rolloff.

        Have fun!
        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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        • #79
          Good Evening!

          The grills are coming along, and I'm really pleased with the results. They're all ready to receive a coat of matte black paint, and then they'll be complete. I will be doing the vast majority of my listening with the grills in place, so I plan to take a new set of measurements with them on before finalizing the crossover design.

          Cheers!

          Joe

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          • #80
            Classy lookin' box !

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            • #81
              The grills are finally complete! There were a few false-starts, but I think it came together in the end.

              Cheers!

              Joe

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              • #82
                Cool, they have real weighty look goin on. (I'm sure they are pretty heavy 😎 )
                A mains
                The Ventures
                Open Invit8tions
                RSR
                Sound Troopers
                Acorns
                442
                DGBG's
                The Monuments

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                • #83
                  they look fantastic , but i'm wondering about the lack of round-overs ?
                  Paper Towers
                  RS180P/28F surrounds
                  Boombox

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                  • #84
                    Thanks! They're a little over 100lbs each.

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                    • #85
                      They look great and fit very well with your furnishings!

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                      • #86
                        Ok, here is the most recent crossover attempt based on the new measurements. I think the ViaWave will be much more comfortable with this crossover, and it looks like I"m getting good summing between the mid and tweeter after reversing the tweeter polarity. The impedance is still dipping below 4 at a couple points, but not too bad. I haven't been able to solve the nastiness at 1khz though.

                        What do you guys think?

                        Joe

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                        • #87
                          Good Evening!

                          After long last this project is finally making music! I've gone through a few different iteration of the the crossover, and I think I've got it pretty close to where I want it to be at this point. Attached is a picture of the "test build" I did to ensure that all the parts would fit in the base of the speaker. I tried to take into consider the potential interaction of the inductors, but with as many as I have, it's probably not 100% perfect.

                          I was pleased to determine that the nastiness at 1,000hz above appears to have been a reflection effect when I took the original PM180 measurement. I should have gated the measurement tighter.

                          I'll post the final schematic and measurements once everything is complete.

                          Cheers!

                          Joe

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                          • #88
                            Just stand that smallest coil up, and aim it like it's going to roll toward the small air-core next to it. That's all I got.

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                            • #89
                              I might have missed it, but what steel did you use and how did you cut it? Also what did you use for the grill sides to raise them off the baffle? And what paint?

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                              • #90
                                Originally posted by ani_101 View Post
                                I might have missed it, but what steel did you use and how did you cut it? Also what did you use for the grill sides to raise them off the baffle? And what paint?
                                The grill mesh is #20 stainless steel mesh. I cut it with a sheet metal snips, which worked well. The grills stand off the baffle on PE grill magnets. The mid-woofers have 1 magnet that align with each of the mounting screws, and the woofers have 2 each stacked up at each of the mounting screws in order to allow enough clearance at full excursion.

                                The paint is Krylov Supermaxx Matte Black. I used this on the grills and the spike feet, and it works great. It bonds well to the metal, and easily gives a very smoother and even finish.

                                The magnets are glued onto the grill frames. I've tested them at pretty high volume levels without any vibration. I also took some FR measurements with the mid woofer grill on and off, and there was no significant difference - there might have been fraction of a dB here or there, but nothing that is discernible by the human ear.

                                The grills ended up costing about $200 between cutting the grill frames, stainless mesh, magnets, and paint, but it's a construction that I would definitely do again, and highly recommend to others. If you have the frames cut with a CNC laser, your imagination is the limit with what shapes you could create. The guys at VMetals http://vmetalsfab.com were great to work with. I sent in a request for quote, and had parts on my doorstep within 4 days.

                                Cheers!

                                Joe

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