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Nice curves... - Scan-Speak 15M/4624G

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  • #16
    Re: Nice curves... - Scan-Speak 15M/4624G

    Originally posted by czag View Post
    I would bet the HD would fall somewhere in between that and the HD of the 18W8434 seen below since the 10F has a copper cap and this one only has an aluminum shorting ring. Now that is still a great place to be for a midrange under $100, much less the $55 this one goes for.
    This brings up a point to make. This is a midrange unit and extra care must be taken to not over-drive it. But then this is no different than for any driver. Certainly the quality of the motor is going to contribute to how much output of the low end of the driver range is possible and for woofers and midwoofers it's a bigger factor. For any good driver with a good motor, except for the case where someone is trying to wring every last mm of displacement from a driver, the distortion is probably not nearly as important because most of the time, we aren't listening at max levels. I know that I seldom do. I probably have never come close to Xmax of any driver except when testing the limits of a system. With a 2-way, if I really need more extension, I'd add a subwoofer and highpass the 2-way. Then again, I likely won't be listening at levels high enough very often, so that 2-way won't be taxed excessively anyway. If you will be, different design considerations then enter. But I suspect that with most of today's good drivers, the T/S parameters are more of an issue than are the absolute distortion numbers.

    If someone has a system that in regular use is approaching Xmax or maybe to the point where distortion really is entering the picture, either the system should be improved in any of various ways (better driver, larger driver, multiple drivers, etc.) or they're going to damage their hearing. In either case, I would not be spending any amount of time in a room with that level of SPL.

    My opinion, and I'm sure many of you will disagree, is that there is an over-emphasis on absolute distortion numbers in evaluating drivers. It's what I might call "the latest and greatest syndrome". This is not to say that it doesn't matter, but everything has a point of diminishing returns. Give me a good driver/motor with smooth and extended response with good polar response in my intended bandwidth.

    dlr
    WinPCD - Windows .NET Passive Crossover Designer

    Dave's Speaker Pages

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    • #17
      Re: Nice curves... - Scan-Speak 15M/4624G

      Originally posted by dlr View Post
      My opinion, and I'm sure many of you will disagree, is that there is an over-emphasis on absolute distortion numbers in evaluating drivers. It's what I might call "the latest and greatest syndrome". This is not to say that it doesn't matter, but everything has a point of diminishing returns. Give me a good driver/motor with smooth and extended response with good polar response in my intended bandwidth.

      dlr
      I agree, as long as this driver is used for its intended purpose and not crossed too low, its' HD distortion performance will probably not really need to be considered in the design. If both of these drivers were crossed from say 300hz to 2500hz, then I don't think you would be able to distinguish lower HD performance when comparing them.

      I was just pointing out that the 15M will probably not have quite as low distortion as the 10F. Will anyone be able to tell? I don't think so, and if someone said they could tell, I would need it to be done in blind listening test to be able to believe them.

      Chris
      Chris

      Goofing around since 2000.

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      • #18
        Re: Nice curves... - Scan-Speak 15M/4624G

        Originally posted by czag View Post
        I agree, as long as this driver is used for its intended purpose and not crossed too low, its' HD distortion performance will probably not really need to be considered in the design. If both of these drivers were crossed from say 300hz to 2500hz, then I don't think you would be able to distinguish lower HD performance when comparing them.

        I was just pointing out that the 15M will probably not have quite as low distortion as the 10F. Will anyone be able to tell? I don't think so, and if someone said they could tell, I would need it to be done in blind listening test to be able to believe them.

        Chris
        Well, driven to the same levels, the 15 will have a distinct advantage in that whatever displacement it does have, it will be significantly less than the 10, regardless the power level or frequency.

        No doubt that either will make an excellent mid unit.
        R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
        Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

        95% of Climate Models Agree: The Observations Must be Wrong
        "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

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        • #19
          Re: Nice curves... - Scan-Speak 15M/4624G

          Hi,

          Thanks for the input fellows, in terms of obtaining a constant power directivity requirements(from a separate thread) a 4" mid(10F) would be a better match to a ribbon tweeter like Fountek CD3.0 or Raal than the 5.25"(15M) mid. If that is the case what would be the best x-over point? The x-over point should be greater than 3Khz and less than 6Khz. If it is greater than 4KHz then 10F is a better choice.

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          • #20
            Re: Nice curves... - Scan-Speak 15M/4624G

            Originally posted by ttan98 View Post
            Hi,

            Thanks for the input fellows, in terms of obtaining a constant power directivity requirements(from a separate thread) a 4" mid(10F) would be a better match to a ribbon tweeter like Fountek CD3.0 or Raal than the 5.25"(15M) mid. If that is the case what would be the best x-over point? The x-over point should be greater than 3Khz and less than 6Khz. If it is greater than 4KHz then 10F is a better choice.
            We ran a 6" wavecor with the 70-10D, crossing around 3200Hz, and could probably have gone a little lower. Horizontal off axis response plots were pretty smooth to 45 deg. No doubt the 10F would be even better, but there's really no reason to cross much higher than 3000Hz with that particular RAAL.
            R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
            Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

            95% of Climate Models Agree: The Observations Must be Wrong
            "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

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            • #21
              Re: Nice curves... - Scan-Speak 15M/4624G

              Troels Gravesen really looked into foam surrounds here
              :blues: Flat frequency response, a smooth sound power response free of resonance, careful driver-integration, and high dynamic range both upward and downward :blues:

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              • #22
                Re: Nice curves... - Scan-Speak 15M/4624G

                Originally posted by GranteedEV View Post
                Troels Gravesen really looked into foam surrounds here
                I don't understand the point you are trying to make here. I understand you have some experience with constant power directivity can you comment on my Post 72

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                • #23
                  Re: Nice curves... - Scan-Speak 15M/4624G

                  I guess this is the only relevant thread for the discovery 5.25" mid....

                  Click image for larger version

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                  24", 5 msec, 1/12th smooth, drive level not checked.

                  Click image for larger version

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                  24", 15 msec, 1/12th smooth, drive level not checked.

                  These were in room on my Nova Forte baffle, YMMV.
                  Last edited by Jay1; 04-27-2013, 11:21 AM.
                  http://jaysspeakerpage.weebly.com/

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                  • #24
                    Re: Nice curves... - Scan-Speak 15M/4624G

                    I have a pair waiting for me at home. Going to re-do my old Driscoll project with them, and a ring radiator Vifa.
                    Don't listen to me - I have not sold any $150,000 speakers.

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                    • #25
                      Re: Nice curves... - Scan-Speak 15M/4624G

                      Johnny, you arent concerned with the extremely limited xmax?
                      http://jaysspeakerpage.weebly.com/

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                      • #26
                        Re: Nice curves... - Scan-Speak 15M/4624G

                        Originally posted by Jay1 View Post
                        Johnny, you arent concerned with the extremely limited xmax?
                        Yeah, I guess I would be if those were indeed the drivers I have *smacks forehead*

                        I have a pair of the 4434G00, much more better useful for what I intend to do.
                        Don't listen to me - I have not sold any $150,000 speakers.

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                        • #27
                          Re: Nice curves... - Scan-Speak 15M/4624G

                          Originally posted by Jay1 View Post
                          Johnny, you arent concerned with the extremely limited xmax?
                          In a small, sealed chamber and crossed LR2 @ 400hz, it will 250 watts without exceeding xmax(114db).
                          "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche

                          http://www.diy-ny.com/

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                          • #28
                            Re: Nice curves... - Scan-Speak 15M/4624G

                            Originally posted by Face View Post
                            In a small, sealed chamber and crossed LR2 @ 400hz, it will 250 watts without exceeding xmax(114db).
                            I dont think that's the application used in JR's Driscoll
                            http://jaysspeakerpage.weebly.com/

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                            • #29
                              Re: Nice curves... - Scan-Speak 15M/4624G

                              Originally posted by Face View Post
                              In a small, sealed chamber and crossed LR2 @ 400hz, it will 250 watts without exceeding xmax(114db).
                              Heh... your ears will MELT if you subject them to 250 watts at 400 Hz.
                              "...this is not a subwoofer" - Jeff Bagby ;)

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                              • #30
                                Re: Nice curves... - Scan-Speak 15M/4624G

                                I know, I was just commenting how it's xmax isn't an issue since it's a midrange.
                                "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche

                                http://www.diy-ny.com/

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