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Thread: JBL 4401s

  1. #46
    RIP 2011 Zilch's Avatar
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    Loading C36 Viscount cabinets:

    1) After thoroughtly sealing all joints, "shoulders" for installation of front and rear baffles get self-adhesive closed-cell neoprene foam weatherstrip. View from rear.

    2) Baffle with T-nuts is installed using #6 x 1-5/8" deck screws, angled slightly outward.

    3) Weatherstrip seals installed on the front for horn and woofer.

    4) Drivers installed.
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  2. #47
    RIP 2011 Zilch's Avatar
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    5) Drivers and horn from inside. Yes, the box needs bracing. Haven't figured that out yet; want to be able to remove the baffle.

    6) Design calls for "heavy" fill. Around here, that means high-density R-21.

    7) STEREO!!

    [Pop quiz - which model are the woofers? ]
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  3. #48
    RIP 2011 Zilch's Avatar
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  4. #49
    RIP 2011 Zilch's Avatar
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    O.K., first listening impressions with Dzihan & Kamien, Patricia Barber, Larry & Lee, Keith Urban, Little Feet; 85 to 90 dB at listening position:

    These have a unique, very pleasant voice. The bass is really big, with full tonality, perhaps a bit TOO big; I may try to knock that down some. In any case, it's different from, and I'd say better than, what a typical ported enclosure would provide. We've discussed the rationale for this over in the Acoustic Suspension thread.

    The mylar diaphragm re-entrant ring radiator high frequency compression driver is smooth and mellow, playing out to 20 kHz. (See the performance measurements.) After hearing the damped titanium of 2452H-SL for nearly a month now, it's tough for me to listen to plain titanium diaphragms anymore. I've always liked these mylars, and of course, aluminum with its inherent damping.

    The $10 PT Waveguide delivers. I'm crossed at 1.2 kHz with 3120A, and that's no sweat for either it or the HF driver. Pattern control is excellent, so tight I gotta be sitting down at 7' since the horn axis is only 24" off the floor in these. If 123A-x can't play well that high, I'm not sensing it.

    These are shallow-frame woofers, physically, and the HF driver uses a thread-on throat adapter, adding depth to it. CLIO says I can achieve optimum time alignment for this woofer/HF driver/horn combination by rear-mounting the 123s. Having the removable back panel on the cabinets will allow me to try that.

    I'd call these a success, and I'm anxious to hear what other listeners will have to say about them.

    [May have to order up some stilettos... ]

  5. #50
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    Nice work, Zilch! The 3120A has CD compensation built-in, right?

    John

  6. #51
    clmrt
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    Z -

    Do you have a day job??

  7. #52
    Senior Member alexkerhead's Avatar
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    Wow, nice!
    I cant wait to start on mine.

    Still gotta find some money for some birch. I almost cheaped out and got pine, but I decided to wait for the right stuff.
    Plus it gave me a chance to see your impressions.

    Is that a 2213 woofer out of a 4311?
    Seems like the same basket, but motor assembly is smaller.

  8. #53
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by johnaec View Post
    Nice work, Zilch! The 3120A has CD compensation built-in, right?
    Yup, with several different selectable slopes, depending upon three settings each, mid and HF boost. I haven't dug into designing a specific crossover for them yet; just trying whatever might at least play them here. The additional L-pad is necessary for these very efficient HF drivers, and gives even more adjustability for balancing with the woofers. New system, I usually grab 31xx to tell me "where I'm at."

    Quote Originally Posted by clmrt View Post
    Z - Do you have a day job??
    It was the weekend. (And very, very, late night listening.... )

    Quote Originally Posted by alexkerhead View Post
    Is that a 2213 woofer out of a 4311?
    Seems like the same basket, but motor assembly is smaller.
    Good guess, Alex, but it's actually the basket that's different. The motors are the same. The clue is on the front. Edgewound earlier documented this difference in the drivers for us:

    The 123A-1 on the left has the terminals and voice coil leads midway between the frame webs, and thus between the mounting holes, so you can see the leads oriented at 12:00. See post #35, second image for rear view of that driver.

    On the 123A-3 on the right, the leads are aligned with the frame web and mounting holes, instead, and thus you see them at 10:30 where I've oriented this driver. See top pic in post #47 - terminals are mounted on the web itself.

    Also, 123A-1 is positive polarity, and 123A-3 (2213) is JBL standard negative polarity convention. You'd know THAT soon's you hooked these up:

    "HEY, where's all the BASS these're s'posed to have? "

  9. #54
    Senior Member alexkerhead's Avatar
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    On AudioKarma, someone recommended a 4"x4" flared port on a 123A-1 in the stock box.
    Maybe something similar would work?

    Just a thought.

  10. #55
    clmrt
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    "Stock Box"

    ?

    4401 box?

    123A, 3 cu ft, 4x4 vent and closed =
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  11. #56
    RIP 2011 Zilch's Avatar
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    Run the sims in WinISD, BB6P, or any box design program.

    Show us ANY port configuration that will "fix" the bass in that too-small stock L100 box short of closing it as I have documented in these forums.

    Not gonna happen, I don't believe. It's a closed-box woofer, according to the T/S parameters....

    *****

    AudioKarma - isn't that where they suggest that woofers need to be at the bottom of a cabinet because bass is heavier than treble and will interfere with it as gravity pulls the bass down?

    [Where is that post again, now? I can find the one where virtual performers are taller with stacked L100s, but not that one.... ]

    *****

    EDIT: Thanks, clmrt! There's our closed-box C36s on a different simulator - Woo HOO!!

    [I'm NOT making the this up AFTER all.... ]

  12. #57
    Senior Member alexkerhead's Avatar
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    His simulation suggests the bass is better than stock L100s, which is excellent, but you were complaining about lack of bass zilch?

    Stock l100s are bassy enough..

    Edit: I mixed them up, I see the problem now.
    Less bass is a pay off for a better curve.
    I downloaded winisd and will mess with it tonight.

  13. #58
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by alexkerhead View Post
    ... but you were complaining about lack of bass zilch?
    Not hardly. The standard complaint about L100 bass is that there is too much, and it is "boomy." Sims and measurements confirm that. I can't imagine anyone but a "Beater" wanting more than what they deliver, standard. Like you say, they're "bassy enough," and as you correctly observe, the objective of my L100 "fixes" with respect to the bass is to strip away the boominess.

    Closing the port accomplishes that, as you'll see in WinISD. The perceived result is loss of bass, but the REAL result according to the measurements is merely loss of the boom, and better, more extended bass. The change is dramatic, and for someone accustomed to listening to L100s, it very likely takes some getting used to; it may also require readjustment of the MF and HF levels, "presence" and "brilliance" to achieve a better balance, as others have suggested here.

    Then, the logical question: "If closing the port on L100 gives it better bass, what happens if you then provide the L100 bass driver with the larger closed box the sim programs suggest it really needs?" That led us to these 3 cuft C36s, wherein we're concurrently also attempting to overcome more of L100s "shortcomings" with a compression driver, horn, and a proper crossover....

  14. #59
    Senior Member alexkerhead's Avatar
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    I see what you are saying.

    Seeing how I adjust my EQ, the closed 3cu.ft design would alleviate the need for acoustic equalization.

    You wouldn't happen to have a schematic of the crossover?

    Since I cannot afford JBL crossovers, I will be making my own.

    The only thing I am saving up for that costs a lot of money are the compression drivers and birch plywood.

  15. #60
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by alexkerhead View Post
    Seeing how I adjust my EQ, the closed 3cu.ft design would alleviate the need for acoustic equalization.
    Yes, that's one element of this. The BIG one is you'll be getting HUGELY better extended bass, as well. (I'm listening to it RIGHT now, from the other room, Larry and Lee again. )

    Alex, I am trusting that by the time you get all of this together, we'll have an appropriate crossover design to work with. JBL 3120A is just one that I use in testing here, because I have it, and it offers some versatility for that purpose, getting me quickly to something listenable, and telling me, generally, what will be required for that. To replicate it would require having the tapped inductor (L3) used as an autotransformer in it for attenuation:

    http://www.jblproservice.com/pdf/Net...%20Network.pdf

    There are better options. Just for information, I'm running HF boost at max and HF gain (MF, kinda) at med. That establishes the requisite compression driver compensation curve Johnaec alluded to above. Consider it passive EQ built into the crossover. Right now, it's similar to the green curve in post #2 here:

    http://audioheritage.org/vbulletin/s...ead.php?t=5376

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