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Right speaker design for Realistic Nova 7b cabinets

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  • #16
    Alright... been thinking about this. Without a sub I suspect you'll be disappointed with the Nova 2 design and it's DA215 woofer. But.... I was just playing with the dimensions of that Nova 7 cabinet in BassBox a bit, and those are actually significantly larger than my Nova 15's. They're a full cubic foot internally, that extra depth and slightly larger height and width make a huge difference. The DA215 will do much better in that cabinet than I have modeled in the design files. A 2" x 5" port should tune you to about 35Hz and get you down to 42Hz, Now we're talking.

    Here are the design files for the Nova 15 cabinet. You'll need WinPCD to open the crossover model "Nova 2.csp". Upon opening you'll have to point it to the FRD and ZMA files for the woofer and tweeter, which I have saved as the part number with Sim. To get a true response model with your larger cabinet, you'll need to update the woofer response model by adjusting the "DA215-8 Woofer Response Modeler3.01" spreadsheet based on your cabinet volume. Then follow the steps to export the updated FRD and ZMA files, then extract minimum phase. I have those parts in my tutorial, but it's no doubt a bit of learning.
    Electronics engineer, woofer enthusiast, and musician.
    Wogg Music

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    • #17
      Thanks for the time and effort you're putting into this. I'm all for the learning. Given the difference in size of our respective cabinets do you feel like the design will still be a good fit or would I be better suited to use one of the others I mentioned originally? I'm good either way if you feel like it's a good fit. I'm also in good shape for those reference drivers (ended up selling my old 5.1 to a buddy)... Now that you already sent over the nova2 file. I'll see about that software this weekend.

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      • #18
        Actually with a box that big the RS180 makes less sense, it ends up running into exertion issues at 10W in the 40-50Hz range. The DA215 woofer works better in the bigger box and will keep under control up to 30W at 50Hz. Here are the screens from BassBox showing what I'm talking about.

        No worries about the time. I've worked on these designs for a while and am sort of excited that one of these may make it to reality before I get a chance to do it myself.
        Attached Files
        Electronics engineer, woofer enthusiast, and musician.
        Wogg Music

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        • #19
          Very cool. Nova2 it is then.

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          • #20
            OK, Wogg. I haven't had a ton of time to dedicate to this as of late but I've gotten through your tutorial a few times (thanks) as well as the YouTube tutorials on Winpcd and have been doing a little homework on crossover design/layout and am slowly learning to understand some simple designs (also making my way through the "bible" sticky). I'm going to be heading out of town again this weekend but would like to get the drivers and any crossover parts ordered that I can before I go. Will there end up being any crossover parts that won't change in value with the new dimensions of my cabinets? I've been fiddling with the baffle dimensions and whatnot on Winpcd but I'm still unclear on a lot of things and need to spend a bunch more time with it. I ended up with internal dimensions of 11.125W x 20.75T x 9.125D after I adjusted for the removal of most of the existing baffle for about 1.22 cubic ft if I figured it right (seems big to me). Should I expect the location of the drivers to change much with my cabinets compared to yours? I wasn't sure if I should be adjusting that within the baffle section on Winpcd.

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            • #21
              The baffle signature is added by the Response Modeler file, which then creates the simulated FRD files for use in PCD. The important dimension will be the outside width of the baffle, on my Nova 15 the baffle is 10.75 wide. Looks like you're are a about 1.375" or so wider presuming the cabinet is 1/2" MDF. That's about 13%, so it may make a noticable difference in baffle step and edge diffraction. The crossover is probably fine with no value changes, but I can't say for certain how much the ripples will change and if a value adjustment will get them back under control.

              The driver spacing in WinPCD should stay the same though, because those are entered relative to the tweeter. The drivers should be placed the same, and referenced from the top outside edge. The tweeter being 7/8" off center and 3" down, while the woofer is dead center and 10" down.
              Electronics engineer, woofer enthusiast, and musician.
              Wogg Music

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