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Klippel: SB Acoustics 17NRXC35-4

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  • Klippel: SB Acoustics 17NRXC35-4

    For full report in PDF format, see link:
    http://www.diymobileaudio.com/forum/...ppel-data.html

    Originally posted by Me
    Thanks to Adam at Madisound for helping me out with this.


    Alright, I just wrapped up testing on the SB Acoustics 17NRXC35-4, 6.5" midwoofer driver.
    SB Acoustics SB17NRXC35-4, 6.5" Woofer: Madisound Speaker Store

    The data is attached in PDF form.

    I ran this particular test 6 times total. The results were always the same.

    Displacement Limits (based on 82%Bl, 75%Cms, etc):
    X Bl @ Bl min=82% 4.4 mm
    X C @ C min=75% 1.9 mm
    X L @ Z max=10 % >4.5 mm
    X d @ d2=10% 26.2 mm















    When you stop caring about being right, you might actually learn something.

    My test data site:
    http://medleysmusings.com/

  • #2
    Re: Klippel: SB Acoustics 17NRXC35-4

    i wish i understood what all this means.
    " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

    Quote Originally Posted by hongrn. Oct 2014
    Do you realize that being an American is like winning the biggest jackpot ever??

    http://www.midwestaudioclub.com/spot...owell-simpson/
    http://s413.photobucket.com/albums/pp216/arlis/

    Comment


    • #3
      Re: Klippel: SB Acoustics 17NRXC35-4

      Originally posted by ErinH View Post
      For full report in PDF format, see link:
      http://www.diymobileaudio.com/forum/...ppel-data.html
      Not knowing enough about the Klippel test, I'm trying to figure out the data.

      The Bl and Cms curves look to have quite a bit of asymmetry. It also looks like they might be trying to counter-balance them. But with the Kms being offset from zero (maybe about 1mm), it appears as though the symmetry isn't as good as one might hope.

      Any of this correct or am I all wet?

      dlr
      WinPCD - Windows .NET Passive Crossover Designer

      Dave's Speaker Pages

      Comment


      • #4
        Re: Klippel: SB Acoustics 17NRXC35-4

        Honest to goodness, guys, I'm still learning as I go. I have a pretty general idea of what each data set means but I am far from an expert. I'm just a trusted tester who has half a brain enough to run measurements and know when to ask for help (thus, I've contacted some of the industry's top professionals regarding the test setup, methods, and data and have gotten surprisingly welcomed responses and invites to continue to use them as a source; one being Patrick Turnmire). wow... that was one heck of a parentheses.


        It's really going to vary as to what the intended use is. For the most part, though, you want linearity and symmetry. The more asymmetrical the data, the more distortion. Again, that's not written in stone. For instance, you could have a nasty asymmetry in Kms (stiffness) but that may not be an issue depending on the passband you're using it in.

        My suggestion is to try reading these links first:
        http://www.diymobileaudio.com/forum/...asurement.html
        http://www.diymobileaudio.com/forum/...-analyzer.html


        If you have any specific questions I'll do my best to answer. It's just that there are a good deal of "what if" that play in to the use of the driver, that making a sweeping generalization other than the one regarding symmetry can be taken out of context (attempt at an allusion there).


        I guess what I really mean to say is: without some experience as a transducer designer, it may be easy to misinterpret the results. Sometimes certain results that look bad may have been intended because the use of the driver dictated that 'bad' trait. If that makes sense.
        When you stop caring about being right, you might actually learn something.

        My test data site:
        http://medleysmusings.com/

        Comment


        • #5
          Re: Klippel: SB Acoustics 17NRXC35-4

          I think this data, combined with FR and HD can really tell you a WHOLE lot about a driver and really, to me at least, represents the trinity of data.

          I suggest you guys who really want to learn more about why a speaker does what it does and what the effect is pick up Vance Dickason's Loudspeaker Design Cookbook.
          When you stop caring about being right, you might actually learn something.

          My test data site:
          http://medleysmusings.com/

          Comment


          • #6
            Re: Klippel: SB Acoustics 17NRXC35-4

            So, we can see that it looses force factor and compliance as x position increases. Also inductance changes a bit. So music reproduction will be less accurate at the x position extremes. Only thing is what to compare it too. I've only seen a couple of these tests.

            Thank you for posting this. I'd say it looks good! Without actually knowing if it is ;) The x position changes don't nose dive abruptly or do any funky wild jumps. Looks like you'd want to use it under ~3mm xmax for the most accuracy.

            Am I close

            Edit - just looked at those links. Maybe it's not "good" ;) I'm interested to see what people think.
            https://www.youtube.com/channel/UCm2...oSKdB448TTVEnQ

            Comment


            • #7
              Re: Klippel: SB Acoustics 17NRXC35-4

              The motor is really good. What would take this speaker into the next level would be a cone change to get rid of the breakup.

              The broad BL curve with the gentle sloping ends shows that the motor is providing near constant force over the entire stroke range. The curves being mismatched shows a little voice coil offset during manufacturing. There is very little Le changing over stroke showing little inductance variation. Both of these can be attributed to the copper sleeve on the pole piece.

              The Kms symmetry graph is also showing a coil out off set of about 1mm or so. The graph is very symmetrical and well resolved over the entire stroke.

              Cms is showing the same coil out offset. And is the limiting factor in throw.

              The bottom graph shows the suspension as the major factor in distortion in this driver.

              Comment


              • #8
                Re: Klippel: SB Acoustics 17NRXC35-4

                Originally posted by winslow View Post
                The motor is really good. What would take this speaker into the next level would be a cone change to get rid of the breakup.

                The broad BL curve with the gentle sloping ends shows that the motor is providing near constant force over the entire stroke range. The curves being mismatched shows a little voice coil offset during manufacturing. There is very little Le changing over stroke showing little inductance variation. Both of these can be attributed to the copper sleeve on the pole piece.

                The Kms symmetry graph is also showing a coil out off set of about 1mm or so. The graph is very symmetrical and well resolved over the entire stroke.

                Cms is showing the same coil out offset. And is the limiting factor in throw.

                The bottom graph shows the suspension as the major factor in distortion in this driver.
                The 8 ohm version of this driver is used in my Mandolin kit. It was not at all hard to cross over. Break-ups like this are not that big of a deal if your tweeter can handle a crossover point below 2kHz, which is the range you should be in for a 7" driver anyway.
                Click here for Jeff Bagby's Loudspeaker Design Software

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                • #9
                  Re: Klippel: SB Acoustics 17NRXC35-4

                  Just me, but below 2k for a tweeter is only good for background music.

                  Comment


                  • #10
                    Re: Klippel: SB Acoustics 17NRXC35-4

                    Originally posted by winslow View Post
                    Just me, but below 2k for a tweeter is only good for background music.
                    Care to elaborate on this, I don't follow you? Are you saying that a speaker with a 1.8kHz crossover point can't be driven hard? That's certainly not the case with most of the tweeters I have used. I think you may be underestimating the capabilities of these tweeters. In most of these two-ways the woofers would be overdriven long before the tweeters would be.
                    Click here for Jeff Bagby's Loudspeaker Design Software

                    Comment


                    • #11
                      Re: Klippel: SB Acoustics 17NRXC35-4

                      I understand where Winslow is coming from.
                      Many tweeters have a rising distortion trend typically below 4khz that is pretty rough at 2khz. This can be seen on Zaph's testing.

                      I'm not saying you can't or shouldnt cross below 4khz. I am saying that, in general, it's dicey here down. Of course, generally, I don't make general statements. ;)

                      It's tough... The polar of 6-7" mids starts going bad in this area so you need a tweeter that can make it that low. Finding one is tough for listening at higher volume due to distortion.
                      When you stop caring about being right, you might actually learn something.

                      My test data site:
                      http://medleysmusings.com/

                      Comment


                      • #12
                        Re: Klippel: SB Acoustics 17NRXC35-4

                        Originally posted by ErinH View Post
                        I understand where Winslow is coming from.
                        Many tweeters have a rising distortion trend typically below 4khz that is pretty rough at 2khz. This can be seen on Zaph's testing.

                        I'm not saying you can't or shouldnt cross below 4khz. I am saying that, in general, it's dicey here down. Of course, generally, I don't make general statements. ;)

                        It's tough... The polar of 6-7" mids starts going bad in this area so you need a tweeter that can make it that low. Finding one is tough for listening at higher volume due to distortion.
                        You guys are making it out to be much more difficult than it really is - the SB29, Usher 9930 & 9950, RS28F, RS28A, Seas 27TDFC, will all cross easily below 2khz with low distortion at a reasonable price; not to mention the numerous higher end Scanspeak and Seas tweeters.

                        I stand by my statement - in a two-way loudspeaker the midwoofer would easily by overdriven long before any of the tweeters I just named if they are crossed over properly. (All of which I have actually used and crossed over below 2khz).

                        I have to disagree, finding one is not tough when the woofer is the limiting component.
                        Click here for Jeff Bagby's Loudspeaker Design Software

                        Comment


                        • #13
                          Re: Klippel: SB Acoustics 17NRXC35-4

                          I want live play back type levels. Such a setup wouldn't do it.

                          Comment


                          • #14
                            Re: Klippel: SB Acoustics 17NRXC35-4

                            What would be the problem if I want to cross this woofer at 2.5K? I think the break up in this case could still be well controlled. The off-axis responses of the woofer isn't that bad either.

                            Comment


                            • #15
                              Re: Klippel: SB Acoustics 17NRXC35-4

                              Originally posted by Jeff B. View Post
                              You guys are making it out to be much more difficult than it really is - the SB29, Usher 9930 & 9950, RS28F, RS28A, Seas 27TDFC, will all cross easily below 2khz with low distortion at a reasonable price; not to mention the numerous higher end Scanspeak and Seas tweeters.
                              Except that used like that (assuming a 180deg waveguide, aka flush mounting) they will all sound unacceptably spitty to someone accustomed to the sounds of unamp'ed live music and high-fidelity reproduction.

                              Properly used (i.e. with some means of controlling their low-end directivity) you're probably right.
                              --
                              "Based on my library and laboratory research, I have concluded, as have others, that the best measures of speaker quality are frequency response and dispersion pattern. I have not found any credible research showing that most of the differences we hear among loudspeakers cannot be explained by examining these two variables." -Alvin Foster, 22 BAS Speaker 2 (May, 1999)

                              Comment

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