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Thread: Quick & Dirty 4430-Inspired Two-Ways Part I

  1. #391
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by DMMD
    Interesting observation Zilch...

    Like an extra dimension of breath? "Breathiness"
    Yeah, that too.

    Mackie would call it "Air," probably....

    I've only heard them for a couple of hours, though, and it ain't as if I have no bias here....

  2. #392
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    Quote Originally Posted by Giskard
    Could be... I've only tried that combo with direct radiators.
    I'll send ya the N200T3's to play with.

    [Then RobH wants them to try, probably, for his 4425 project....]

  3. #393
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    No thanks!
    Mike would kill me, and rightfully so, if he knew I was screwing around with my 4430's instead of working on his subs.
    Send them directly to Rob.

  4. #394
    RIP 2011 Zilch's Avatar
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    O.K., so what's this tell me about 2431H on PT-F waveguide?
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  5. #395
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    It tells you that you need to get some impedance compensation going on.
    That's not too awful though! JBL is getting good with the impedance curves on these transducers!
    Post the data file.

    Run an impedance curve on just the 2431H so you can see how the waveguide is loading it.

  6. #396
    RIP 2011 Zilch's Avatar
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    O.K., new runs, first with waveguide, then just the 2431H driver.

    Supposedly, not good to run the driver with no horn loading, but the current is only 3 mA, .054 mW typical, 0.1 mW max, if my math is right. Still loud, tho....

    Compression drivers are quite amazing. Seems like a coupla wires stuck in a potato would play 'em....
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  7. #397
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    Quote Originally Posted by Zilch
    Supposedly, not good to run the driver with no horn loading, but the current is only 3 mA, .054 mW, if my math is right. Still loud, tho....
    You can run any driver with that and not have a problem. Don't forget the C.D. is roughly 118 dB with 1 W without any horn loading. That's why it's so loud with minimal input.

    If you could post the output files for BB6P in a zip that would be neato.

    The bb6p .log file will include the sweep necessary for the Q and Fs test.

    The .woo file should be the same as the exported .txt file.

    Here's what I just got running a 2425H/2344A
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  8. #398
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    It's certainly clear in comparing the curves from the two different driver families that they require different crossovers.

    What sweep ratio did you use there? I used 1.0, then switched back to the default 1.3 for the Q test. Run below is at 1.1 for 104 data points.
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  9. #399
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    I can't remember what I put the number of points on, it was high though.

    I wanted my graph to look as much like yours as possible for this little exchange so I started at 500 Hz too. Makes sense for these specific combinations.

  10. #400
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    PT-H vs PT-F Waveguides

    Here's the same 2431H driver on square-format PT-H versus rectangular PT-F waveguides. Both are 100° X 100° shown earlier in this thread.

    Surprisingly, smaller PT-F waveguide combo has lower Fs. Not shown, Fmin, the equivalent of box tuning on a LF system, is 1288.49 Hz for the PT-H, and 1087.54 Hz for the PT-F. Seems I may have made a good choice between the two for the L200 upgrade described earlier here.

    Crossover tuning will be slightly different for them as impedence peaks occur at different frequencies, but above 3 kHz, they appear to be virtually identical.

    What's this about? New Dayton Audio "Woofer Tester 2" quickly and easily runs impedance curves on compression driver/horn combinations as well as woofers, providing information for importing into BB6P software for crossover design.

    http://audioheritage.org/vbulletin/s...ead.php?t=5662

    It connects to USB port, which provides the requisite power for these small-signal measurements, and runs even on crappy old machines like this Compaq WIN98 SE system....
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    2430h

    2430H
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    2431h

    2431H
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    2435h

    2435H
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  14. #404
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    Very interesting... look at those high FS numbers. Also look at that pronounced ~14Khz breakup mode on the 2431H... no wonder it sounds a bit harsh.

    The 2435H is definitely the one to get. We should measure the Fs change when adding a larger back cap.

    Widget

  15. #405
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    WOW, Giskard!

    Thanks for getting the scoop on the 243X drivers for us!

    Looks like Woofer Tester's doing a resonable job on the measurements of actual units, here.

    My 2435's don't seem to have HF extension like the spec shows. Guess I'll be sending them back to JBL for a warranty look-see as anticipated....

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