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Thread: Audible Physics XR6.5M

  1. #1
    Tester Extraordinaire ErinH's Avatar
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    Audible Physics XR6.5M

    For test setup, procedures, and information on how the data was obtained see sticky here:
    http://www.mobilesoundscience.com/f1...istortion-693/
    Do not ask setup questions in this thread. This thread is only for driver discussion.

    To understand how to read the data, try here:
    How to read Frequency Response and Harmonic Distortion Plots - DIYMA.com



    Driver Tested:
    Audible Physics XR6.5M:






    Impedance and T/S Parameters:



    Frequency Response at 0 degrees, 3dB scale:


    Frequency Response at 0, 15, 30, and 60 degrees, 5dB scale:



    Harmonic Distortion at 95dB:



    *** Special Note:
    When testing this speaker I found that the distortion at 95dB was, indeed, legitimate. I tested at a few various levels and as you can see below, there is still an odd phenomena occurring at ~ 6-8khz. This seems to correlate with the primary frequency. The sound card gain inputs did not clip but came extremely close, which is what prompted me to test at a lower level (below).

    I can, however, verify this occurred in multiple tests. What you see is exactly what I got with a voltage output required to drive the driver to 95dB, which was calculated from my measurement (and which almost exactly matches the mfg spec @ 1w/1m).
    I'd hazard a guess that the 3rd order harmonic phenomena is tied directly to the frequency response in this region. As I sat in the room during one of the tests to make sure nothing was going on with the test setup to cause the occurrence, I found that the response in this region is very audibly high.

    As backup, here's the limited bandwidth distortion at 90dB.
    Limited Bandwidth Harmonic Distortion at 90dB:
    Your ears: The best tools you have... and they're free, too!

  2. #2
    Founding Member 86mr2's Avatar
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    Magnesium cone breakup is a harsh mistress. You can see so clearly how the third harmonic of 1.7 and 2.1 (-ish) mechanically excite the cone breakup. Same thing goes on in Seas Excells. I would think that the Seas Lotus Ref165 behaves similarly (looking at Seas' published F/R graph) - for more money.
    Last edited by 86mr2; 05-01-2011 at 06:41 PM.

  3. #3
    Devil's Advocate Adam_MSS's Avatar
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    Pretty stark contrast with the http://www.mobilesoundscience.com/f1...706/#post10504 w/ regard to breakup.
    Last edited by Adam_MSS; 05-02-2011 at 10:12 AM.
    You don't use science to show that you're right, you use science to become right. - R.Munroe

    The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them. - W.L.Bragg



  4. #4
    Founding Member 86mr2's Avatar
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    The Revelators would certainly be easier to work with, but haven't some users destroyed the cones in cars?

    I like the idea of using a mag coned driver, but the cost and size and mounting misery of a sufficiently robust tweeter gets in the way. I also found in my experiment with RS 180s that metal drivers can be rather unforgiving of my admittedly lo-fi musical tastes.

  5. #5
    Tester Extraordinaire ErinH's Avatar
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    Just an FYI, the bolded green plot that lies mostly at the bottom is THD, which is given in magnitude up to 14% in the scale on the far left. I like having it in there as it really helps define the more extreme problem areas with graphs. I have and will continue to do this for all my graphs.

    Regarding this driver measurements, it's pretty clear to see some potential resonances when you correlate the impedance and sole FR results.


    I'm actually awaiting Mark's input. I know that he genuinely goes through quite an interative process when he's deciding upon designs. He's often told me that he never sees a graph until the final design is chosen; the end result is achieved solely by voicing. So, I'm curious to see if he has any input on the boost above 4khz.

    I do myself a disservice (but yet, potential a service to the community as it bars me from wanting to put out anything subjective) by not listening to these drivers when I do my testing.
    I certainly have a lot of subjective thoughts on the objective data but I do my best to keep them to myself. ;)
    Last edited by ErinH; 05-01-2011 at 10:32 PM.
    Your ears: The best tools you have... and they're free, too!

  6. #6
    Senior Member cvjoint's Avatar
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    I really like the scaling on the THD plot now, it's very useful. The Seas mag cones do have similar behavior but from what I can tell they are a bit better controlled than this one. Still, they are almost twins compared to the Scan Speak. I played a lot with the mag Seas cones anything from the Mg/Al 10" hybrid to the 7s. Then I had a Revelator too. While the Magnesium sounds exciting and different it got me very tired over the long run. I tend to agree with Zaph that nonlinear distortion may not strike you at first but sooner your later your ears will tire out. I run all soft cones now, not as exciting but much easier to live with.

  7. #7
    Founding Member 86mr2's Avatar
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    I notice Mark intends that this driver be used with a 3" widebander which makes loads of sense. I have yet to meet the widebander I personally love, but the principle is solid.

  8. #8
    Devil's Advocate Adam_MSS's Avatar
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    Agreed. Used with a widebander you eliminate the distortion issue up top. As a midbass it looks very good and the broad bump in te response from about 200hz down is probably desirable in many circumstances.
    You don't use science to show that you're right, you use science to become right. - R.Munroe

    The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them. - W.L.Bragg



  9. #9
    Mated with the XR3M-LE and you have a pretty nice combination. I actually cut -1.5db to -2.5db in the 16kHz and 20kHz range.

    Chuck

  10. #10
    Senior Member cvjoint's Avatar
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    I was wondering... This driver has a giant breakup at 6khz, and while it may not be nice to listen to, it's still theoretically output. SE doesn't know the difference between distortion and the original signal. So this driver might have a high sensitivity rating but it's mostly driven by the giant breakup. Let's say we bandpass the driver 100hz to 3000hz. Over this range the actual sensitivity is much lower. I wonder how things would be different if we performed an HD test under a limited band passed filter network. My guess would be that sensitivity would be much lower and THD would be higher as well. I mean, the speaker would have to be tested at more actual amplifier power and the distortion would move up.

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