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Thread: JBL 2446H measurements question

  1. #1
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    JBL 2446H measurements question

    For the last year or so I have been building a multicell mid-bass horn, purchasing two used JBL2446H drivers, along with putting together a measurement system. The horns are built, I have been testing the JBL drivers and have some data to post and inquire about interpreting some of the graphs
    All the graphs are driver alone, no horn. I used REW software, with a Mini DSP mic. The mic was positioned 2 inches away from the driver exit. Below are measurement graphs:

    SPL + Phase
    Impulse
    Spectrograph
    Waterfall
    Impedance
    Distortion

    My concerns are the spectrograph, impulse, along with the impedance graph with the large second spike at 1300 Hz, as this is within my midrange horns coverage. I have performed frequency sweeps, played music with the horns and cannot detect any obvious issues, other than a frequency response rise at 1300Hz, which I believe is associated with the impedance rise at that frequency.
    Does the spectrograph look normal, or is that proof of a damaged diaphragm?
    Dose the Impulse file look normal, or does the graph show ringing?

    Any help is appreciated
    Tom in Lafayette
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  2. #2
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    Shouldn't you be using a horn?

  3. #3
    Administrator Robh3606's Avatar
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    That doesn't look right. Where is the roll off above the mass break point and why do you have multiple impedance peaks??

    Rob
    "I could be arguing in my spare time"

  4. #4
    Senior Member Baron030's Avatar
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    Yes, you really need to do your tests with the driver attached to the horn you plan on using for your project.
    The horn is going to put an air load on the diaphragm and that is going to effect the impedance response curve.
    And the horn and also going to impact the frequency response as well.
    I happen to be using the same driver with a JBL2382a horn and I get a very different curves.

    Baron030

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  5. #5
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    To all - Thanks for the replies

    Since I purchased used drivers, my question is. are the diaphragm damaged, causing the irregularities in the Impedance plots,
    along with, what looks like ringing in the Spectrograph plots?

    This is why I measured the driver alone, then with the horn attached, so one did not effect the other

    At the end of the day do you suggest new diaphragm ?

    Here are 2446H plots with the horns attached


    Thank,
    Tom in Lafayette
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