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Thread: Screen Array

  1. #1
    RIP 2011 Zilch's Avatar
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    Screen Array

    Vertically asymmetric (20° + 30° x 90°) "Second-generation Optimized Aperture™" mega-PT ("Progressive Transition™") waveguide, 30" W x 15" H, available in both 1" 2374 (126-00177-00) thread-on and 1.5" 2384 (126-00177-01) bolt-on throat variants:
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  2. #2
    Dis Member mikebake's Avatar
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    Not good...................

  3. #3
    RIP 2011 Zilch's Avatar
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    Dunno yet.

    How low do it go?

    What's the SSC™ "Screen Spreading Compensation" about? :dont-know

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    Administrator Robh3606's Avatar
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    So 50 with a downward tilt?

    Rob
    "I could be arguing in my spare time"

  5. #5
    RIP 2011 Zilch's Avatar
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    Or upward, Rob, as I believe I have it sitting there, the mouth wider at the top.

    Think Altec Model 14's asymmetric MantaRay MR931, which was a bit more of an extreme split:

    http://www.lansingheritage.org/html/...ents/mr931.htm

    [Minimize floor bounce.... ]

  6. #6
    Administrator Robh3606's Avatar
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    Or upward, Rob, as I believe I have it sitting there.
    Right either way depending on the speaker height and the type seating in the venue they are used in. I am thinking flat vs stadium as an example.

    Rob
    "I could be arguing in my spare time"

  7. #7
    Senior Member grumpy's Avatar
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    SSC

    http://www.jblpro.com/catalog/suppor...=864&doctype=3

    (p19)

    e.g., hotter on-axis vs. off compared to non-SSC design (simplification).

    Have fun w/ dat.

  8. #8
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by grumpy View Post
    e.g., hotter on-axis vs. off compared to non-SSC design (simplification).
    I'll see what the measurements say, but I read that as saying the HF comp is being done by the waveguide, and I do see it (the means) in the rising DI and narrowing horizontal beamwidth, but it appears to be well and precisely controlled.

    Normally, it says, you'd have to add HF comp, but with SSC™, you don't have to? Normally, you'd have to do that anyway for flat on-axis response with a constant-directivity horn or waveguide. Here, it looks like they're progressively beaming the VHF, from 90° to 65° or 70° horizontal beamwidth, instead, to accomplish it, and correspondingly less HF comp should be required.

    The Klipsch Tractrix KPT-402 horizontal beams at twice that rate, and rather more messily all the way:

    http://audioheritage.org/vbulletin/s...211#post235211

    What am I missing? We're giving up a controlled amount of power response uniformity at higher frequencies so as not to have to apply the requisite additional boost? I'm certainly not afraid of either.

    Thanks for digging out the curves, which do not appear in some of the product data sheets, Grumpy....

  9. #9
    JBL 4645
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    I’d say a safe bet is 500Hz or 800Hz upwards.

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    Intrigued!

    Following with interest here Zilch,

    Thanks for the headsup, I certainly am looking into these,

  11. #11
    RIP 2011 Zilch's Avatar
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    What Grumpy said:
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    Am I correct in reading that CD comp is still needed here?

    What drivers have you tried now and what xovers as well?

    -------------------

    And it looks like the horn has a "boost" at around 20K?

  13. #13
    Senior Member Skywave-Rider's Avatar
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    Zilch,
    Very interested to see what happens w/ BMS 4555 19kHz spike on these, as that would be my option.

    Thanks for doing all this.

    I anticipate a group buy of perf screen for acoustic filtering.

  14. #14
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by kegger View Post
    Am I correct in reading that CD comp is still needed here?
    Yes. I've shown it with the stock Model 19 passive compenstation set at max, which provides ~9 - 10 dB of "boost" via midband attenuation.

    That's not enough with this driver, but it gets this combination into the realm of "listenable."

  15. #15
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Skywave-Rider View Post
    I anticipate a group buy of perf screen for acoustic filtering.
    Stock JBL Blue grille cloth alone certainly doesn't get it, Gray, Black:
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