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

  1. #61
    RIP 2011 Zilch's Avatar
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    CLIO measurement results for Everest horns available here:
    http://audioheritage.org/vbulletin/s...3333#post63333

    4660 used them two-way in a limited HF extension (16 kHz) max SPL (99 dB) sound reinforcement application. By contrast, 4430 is 93 dB SPL.

    Everest used them for mid/high in a hifi three-way, 100 dB system SPL.

    Will they work as a hifi two-way as well? Clearly, we can extend the VHF, but the differentially variable VHF response along the horizontal axis is "troublesome." We'll see. Gotta set me up a turntable (lazy Susan) here to determine what's actually going on....

  2. #62
    RIP 2011 Zilch's Avatar
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    PT-H95

    Deep throat 12" square format 90° x 50° Progressive Transition waveguides (more appropriately "horns," actually,) are WAY deeper than the 100° x 100° version (left), measuring 9-3/8" between mounting surfaces. For those unfamiliar, that's a 1-1/2" exit 2431H neodymium magnet 3" aluminum diaphragm compression driver mounted to it there. (Whew! )

    They have substantial but smoothly contoured constrictions in the throat, apparent in the second pic. Throat gradually narrows to about 9/16" in there. Can't guess how they molded that....

    Shown at bottom on RTA with 2431H's and biased "AM" crossover, they also accept 1" threaded drivers using JBL throat adapter as is shown mounted to the shallower waveguide in the top photo.

    See http://www.jblproservice.com/pdf/AE%...4212,95-WH.pdf

    And http://www.jblproservice.com/pdf/AE%...6212,95-WH.pdf

    Also http://www.jblproservice.com/pdf/AE%...6215,95-WH.pdf

    How do they sound? Well, just fine.

    A minor crossover tweak could get them playing perfectly flat, as there's beaucoup HF extension available.

    Image freaks will like them better than the 100° square version since their vertical pattern is substantially tighter, and thus, they don't create as much early reflection off the floor and ceiling.

    Doesn't look like mechanical time-alignment would be practical, tho; gotta do it electronically, if desired.

    60° x 40° version is available for those liking the sound field even more controlled, but it requires a different crossover, at least in the PT-F version.

    Still waiting on the rectangular PT-F version 90° x 50°.

    [Gonna go listen while I wait, now.... ]
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    Senior Member stevem's Avatar
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    Man those things are deep! I wonder why, because the 2332 horn has about the same dispersion pattern, and they aren't a lot deeper than the 100X100 PT waveguide. The 60x40 PT version isn't as deep either. Why do you suppose this is? Any word on how long it'll be untill JBL starts making the 90x50 rectangular?

  4. #64
    RIP 2011 Zilch's Avatar
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    It's not apparent in the pics, but the long throat encloses an extended transition area between the 1.5" entrance and the constrictions. That accounts for about 4" of it.

    I have the PT-F95 on order. If the PT-H is any indication of the requisite geometry, I can appreciate why they're not making it.

    The rectangular SR horn alternative may be coming in soon, too. I believe TimG has these, but has not reported on his testing of them yet. It's 1/2" taller at 7" x 12"; from the drawing it does not appear to be as deep as the PT-H95:

    http://www.jblproservice.com/pdf/SRX...es/SRX712M.pdf

    And don't forget the really cheap one for 1" thread-on drivers, now also called a PT waveguide. It's a surprising performer, and is what led me to pursue these others for the 1.5" neo drivers:

    http://www.jblproservice.com/pdf/AE%...2215,95-WH.pdf

  5. #65
    RIP 2011 Zilch's Avatar
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    Under test using a forum member's new 2431H's, which produced the RTA curves above. Note depth in comparison to the L200's they're sitting on here.

    Excuse the clutter, please. It's my proprietary approach to room damping.
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  6. #66
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by stevem
    Man those things are deep! I wonder why, because the 2332 horn has about the same dispersion pattern, and they aren't a lot deeper than the 100X100 PT waveguide.
    Does 2332 have the same mounting hole patten? 2431 and 2451 the same?

    There's apparently another one, 75° x 50°, I haven't tried, but it looks deep also:

    http://www.jblproservice.com/pdf/SRX...es/SRX715F.pdf

    Simple crossover, a plus.

    [I ain't doin' no 2352. Nope, nope....]

    OH, and H9800, of course.

  7. #67
    Senior Member stevem's Avatar
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    Quote Originally Posted by Zilch
    Does 2332 have the same mounting hole patten? 2431 and 2451 the same?
    The 2332 has two 4-hole bolt patterns. The inside ones are about 2 1/4" apart, and thats what fits my 2450SL drivers. The outer bolt circle holes are about 3 1/4" apart. Maybe for the 2451? The PT wave guides have the same 4-hole bolt circle of 2 1/4" spaced holes, in addition to another two holes for I don't know what. What pattern do the 2431s use?

  8. #68
    Senior Member stevem's Avatar
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    By the way, I pulled out my 100x100 square PT waveguides to give 'em another try. I like them better this time, because they seem to put more HF into the room, and I don't get the feeling I need a VHF driver. I'm going to play around with them some more. I once read that the best thing about this hobby is that when you change something, It sounds better, and when you change it back it sounds better again! True!

  9. #69
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by stevem
    The PT wave guides have the same 4-hole bolt circle of 2 1/4" spaced holes, in addition to another two holes for I don't know what. What pattern do the 2431s use?
    243x drivers bolt direct to the 4 holes in the PT waveguides. The extra two holes in them align with pins in the optional throat adapters (for 1" thread-on drivers) in the proper orientation vis-a-vis throat constrictions in both the waveguides and the adapters.

    Quote Originally Posted by stevem
    I like them better this time, because they seem to put more HF into the room, and I don't get the feeling I need a VHF driver.
    Yup, that's the prime objective here. As long as the driver and crossover can provide the requisite HF extension gracefully, two-ways RULE!

    [Well, there IS other stuff gotta happen, too.... ]

    2332 is a 90° x 40° "Optimized Aperture" horn. Sebackman tried to use 'em two-way with 2451's, and while they measured O.K., he ended up adding VHF drivers:

    http://audioheritage.org/vbulletin/s...ead.php?t=3774

    "The roll off proved difficult to cure through the XO's so I added two tweeters." Didn't try passive HF boost, apparently.

    I'm wondering how they'd play with 243x's, which appear to meet OA design criteria. Anybody got a pair of 2332's they'll send here to try?

    2451 has 4-1/2" mounting bolt circle. 2450SL has 3-1/4", same as 243x, looks like. I recall now 2332 has holes for both:

    http://audioheritage.org/vbulletin/s...t=3283&p=34688

  10. #70
    Senior Member stevem's Avatar
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    Zilch, do you happen to know what the lowest recommended crossover frequency for the larger (12" by 12") PT waveguides is? So far I've been using 1.2khz, but the 2450SL will go a lot lower (500 hz).

  11. #71
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by stevem
    Do you happen to know what the lowest recommended crossover frequency for the larger (12" by 12") PT waveguides is?
    There's nothing published on that. All we can do is extrapolate from how JBL has used them in combination with results of our own measurements.

    I'm using them at 1 kHz, but from our testing, even that's pushing it. These are "High-Frequency" PT waveguides according to the JBL Tech Note. See the Horn/Driver thread:

    http://audioheritage.org/vbulletin/s...ead.php?t=6050

    Try it, test it. My own guess after re-reading: 800 Hz, maybe, if driver geometry works in your favor. General purpose drivers (2426 and LE85) played a bit lower than 243x's on them. See Post #9 over there.

    500 Hz? No way....

  12. #72
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    "AM" crossover (w/Giskard's HF mod) modeled in X3P includes HF driver/waveguide response (2431H/PT-F1010). LP is N3134 (4430) and 2235H.

    Looks like RTA curve, very familiar.

    Gettin' close to having a handle on what's happening here :

    [Tweak with impunity, now....]
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  13. #73
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    Tweaked, with box response (B380) included, +/- 3 dB from 30 Hz. to 19.8 kHz. Another try, I got within half that, but I like this "room corrected" response slope better.

    HF response transcribed from here: http://audioheritage.org/vbulletin/s...t=6050&p=57027

    X3P calls my T/S parameters for 2431H/PT-F "bogus." Tough noogies, X3P; I averaged actual WT2 values for 6 drivers to get those numbers.

    Note to Guido: Blue @ 10 kHz is per original AM schematic (4.0 Ohms, 0.08 mH), red is as JBL produced it (2.5 Ohms, 0.04 mH), the values we're using. Surprising it makes such a huge difference (~4 dB).

    Powerful stuff....
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  14. #74
    Senior Member Guido's Avatar
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    This looks so damned GOOD
    Seems XoverPro is a nice toy

  15. #75
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Guido
    This looks so damned GOOD
    It's time you BUILT 'em, dude.

    I'm TIRED of havin' all the fun here....

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