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PE Sound Solutions Speaker Design Highlight

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  • PE Sound Solutions Speaker Design Highlight

    First, congrats to Nick on the under $200 winning design. Nick has been very generous with his time to me personally, so I wanted to say thank you, and hopefully this post does not come off as anything other than helpful. I'm posting because I looked at the design posted on page 23 and noted a couple of interesting things. Perhaps this can be a teachable moment for me, or perhaps this will save someone from making an error trying to replicate this design.

    My questions:

    1. I've never seen a high-pass crossover start with an inductor (ignoring the resistor). Is this a common practice to start a 4th order electrical filter with the inductor instead of the capacitor? If this is not correct, what is the right filter component arrangement?
    2. Does the 0.75mH inductor in the 3rd order low pass seem abnormally high? I checked this in a sim and get about a 5dB gain at just over 2kHz in the transfer function. There is no peak in the Omnimic response plot on page 23, so is this so acute at one frequency that it does not show up in a frequency response measurement?
    3. I removed the short circuit in the diagram in PE's flyer when I tried simulating the PE published design.
    Click image for larger version

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  • #2
    No, that is an error. I believe that Nick has addressed this error with PE already.
    https://www.facebook.com/Mosaic-Audi...7373763888294/

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    • #3
      Click image for larger version

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ID:	1421055 I am at fault for the crossover, I flubbed the part placement in the diagram. Here is the corrected schematic.

      Ross as far as the transfer function is concerned, It is close to being the inverse of the woofer response before roll off.
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      There really isn't any gain, it's more of a belly before rolling off. If this was a tweeter and the low end had this shape before cut off that would be putting stress on the tweeter due to added excursion, but in this scenario it works out just fine as this mid woofer doesn't have a nasty breakup or rising distortion.
      Last edited by ugly woofer; 09-07-2019, 08:52 AM.

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      • #4
        Nice design Nick!
        Craig

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        • #5
          The beauty I believe also with a resistor ahead of the tweeter filter instead of conventional L-Pad following, is you can tweak level if you need without altering the phase relationship with woofer.

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          • #6
            Thanks again Nick. Is the transfer function completely independent of the driver? If so, then entering the components in the correct fashion should yield the exact same transfer function. This is what I get as a transfer function. Am I missing something here about the transfer function?
            Click image for larger version

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            • #7
              The xfer fn is determined by the filter topology and how it interacts w/the driver's Z-curve.

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              • #8
                Originally posted by PWR RYD View Post
                Nice design Nick!
                Thank you! I plan to bring them to meniscus.

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                • #9
                  Nick, could you share a picture of the "waveguide" that you integrated into the grill?

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                  • #10
                    Sorry Ross I didn't take any pictures, but I know that I got creative with a large round over bit and the grill is 1/2" mdf. If you want to try something like this, just remember that the throat has to be the same diameter as the tweeter and you need some way of keeping it centered, be it with pegs, push on grill connectors or whatever.

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                    • #11
                      Ross here are the transfer functions with the same filter but using the zma for a rs100p and TB w69. You can see how the impedance changes the transfer function of the filter. Click image for larger version

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                      • #12
                        As Chris said the transfer function is controlled by the filter and impedance of the driver.

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                        • #13
                          Congrats Nick!
                          Failure is not an option. It comes bundled with Windows.

                          We are passionate about great sound at whatever level we can afford, so don't let the audio atheists reduce the experience to a set of numbers and squiggly lines. - jbruner

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                          • #14
                            Originally posted by S7910 View Post
                            Congrats Nick!
                            Thanks, I'll see you at Meniscus.

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