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  • Modeling

    Would any of you be interested being paid to model the 6.5 purifi in a sealed box?

  • #2
    I couldn't take payment for a five minute job. After choosing which of the five 6.5s they make be advised that being low Q they're much better suited to a vented enclosure. Besides, if you're serious about making speakers you need to learn how to do your own modeling. It's not difficult, and it's free.
    www.billfitzmaurice.com
    www.billfitzmaurice.info/forum

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    • #3
      Agree with Bill. If you are going down this custom design path and already wanting to pay someone to model a sealed enclosure....just understand that modelling a sealed enclosure is probably one of the most fundamentally basic aspects of speaker design. If you're stuck here...consider building a kit instead because successful custom design only gets more and more complicated from this point.

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      • #4
        Originally posted by cornajatwa View Post
        ...model the 6.5 purifi in a sealed box...
        http://audio.claub.net/software/kougaard/ubmodel.html

        "Our Nation’s interests are best served by fostering a peaceful global system comprised
        of interdependent networks of trade, finance, information, law, people and governance."
        - from the October 2007 U.S. Naval capstone doctrine
        A Cooperative Strategy for 21st Century Seapower
        (a lofty notion since removed in the March 2015 revision)

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        • #5
          I see Bill has checked and their are multiple versions. I think if you say exactly which one, someone will model it for free if you are assuming they will use manufactured specs.

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          • #6
            Two of them are listed at Madisound, along with suggested box sizes. The sealed only have an F3 of 87Hz, which is a complete waste of a driver with its capabilities, as well as a waste of spending what IMO is an exorbitant price if one doesn't at the very least take advantage of the 35Hz F3 they can deliver with good output from a ported box.
            www.billfitzmaurice.com
            www.billfitzmaurice.info/forum

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            • #7
              The plan was to extend it by going active

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              • #8
                It’s a fancy driver so I wanted to lean on some authority. It’s too pricey to risk knocking the bottom out of it

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                • #9
                  I've never found any of these Purifi drivers to dig that deep in simulation. Most of them struggle to get below 50Hz before going U shaped. You CAN put it in a 25L box tuned to 35Hz and get an F3 of 35Hz but it actually spends the entire time under 100Hz -3db down to do it...so thats -3db 35-100hz, not just 35hz. It'll take 30watts before x-max in this scenario and only musical content below 30hz would upset it.

                  However, once you factor baffle step and try and balance things out to work with this you're dealing with a very low sensitivity final system. Boosting it with active is just going to further limit power handling and reduce the overall max output.

                  Sealed F3 is 85hz as Bill mentions.

                  I'd say the sweet spot for these things is something like a 15L bookshelf tuned to 45Hz or mid-woofer duties in a larger 3way system.

                  Just because they are really expensive does not in any way guarantee that using them is going to give you a superior overall speaker.

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                  • #10
                    Probably better off buying a couple of Denovo Anarchy's for far less money considering the over-all efficiency of the final product.

                    https://ampslab.com/blog/2020/11/19/anarchy704/

                    https://ampslab.com/blog/2020/12/14/anarchy-xt/

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                  • #11
                    WinISD (free) is at linearteam.org (sc).

                    Modeling "PTT6.5X04-NFA-01" (Qts = 0.27, Vas = 0.92cu.ft., Fs = 30) in 1/2 cu.ft. (about 14L) using a 2"id x 8" long port tube, tunes the box to the low 40s (Fb) w/extension down to 40Hz (F3), and that's all you need for most music.

                    To drive it past its 9.8mm Xmax you need mid 30s content @ 150w RMS.

                    When going from a vented box to a closed one, VERY commonly the box size halves (0.25cf) and the F3 (reach) doubles (80Hz or so).

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                    • #12
                      Originally posted by Chris Roemer View Post
                      To drive it past its 9.8mm Xmax you need mid 30s content @ 150w RMS.
                      Ah yes, I was looking at the "w" version which has 5.9 Xmax

                      The 'X' version digs a little deeper, as you say, 14L 40Hz is about optimum

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                      • #13
                        Originally posted by cornajatwa View Post
                        The plan was to extend it by going active
                        Going active doesn't increase the voice coil capacity. Every 6dB of bass EQ quadruples power.
                        It’s a fancy driver so I wanted to lean on some authority. It’s too pricey to risk knocking the bottom out of it
                        The reason they're pricey is that they can handle the low end, thanks to the very long xmax. Why do you want to use it? Because it's pricey? Before spending ten times what you may need to you should step back and research what's required for what you want to do. That includes learning how to model.
                        www.billfitzmaurice.com
                        www.billfitzmaurice.info/forum

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                        • #14
                          I’ll take a closer look at that other version.
                          Thank you Chris and dezzar

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                          • #15
                            Some modeling software that is dead simple to use, AJ Sealed and AJ Vented:

                            https://www.ajdesigner.com/speaker/

                            WinISD is my favorite for serious design, but if I just need a quick estimate I use the AJ software.
                            Francis

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