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Thread: Acoustic (Air) Suspension

  1. #46
    Senior Member Rudy Kleimann's Avatar
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    Most people who own L100's (or other AlNiCo systems like the L26 and L36) and plug the port will notice LESS bass, and will have an urge to turn up the bass before they realize what the truth is, response-wise. And, with no flopping of the cone and all the focus on the cone control afforded by the A-S design, some may want to see how much they can get out of the woofer in this "new" box. Wouldn't want to see or hear about any "long faces" when they realize it is too late, since demagnetization is only reversible by ripping the cone out to recharge the magnet. That's all I was getting at. Moldyoldy had al;ready brought up the coil burnout issue...


    It is well known that the box size was chosen for suitability as a near-field monitor. JBL figured that any bigger cabinet would knock it out of the running. How large would be tolerated sitting atop one of the two most important -and expensive- components of a studio? (cabinet crashes onto the control surface). It was also designed to emulate the sound of the old Altec/Urei duplex monitors that were the industry standard then, while sitting out in the middle of the room with no boundary reinforcement. Hence the boomy bass.

    I find it surprising that BBPRO says the 123A in the cab is a good alignment. We all know it is not just by listening to them. Sure you didn't miss on your measurements or your math? On a box that size, a little means a lot re: percentage of volume change.

    The A-S "Q" is too high, as you can see and probably hear. That is why I said the box is too small for either, really, IMHO.

  2. #47
    Senior Member Rudy Kleimann's Avatar
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    watch the stuffing near the port!

    Quote Originally Posted by SETriode
    Stuck some poly fill inside my l100 cabinet today after installing my 104hs and I wasn't too impressed. Perhaps I'll have to start experimenting later, but in this application (where the woofer half of the midrange) i think you've got to pick either blocking the port or stuffin the box with insulation. Polyfill was just too much and all i had left was HF and upper MF, so for right now I'm gonna leave em be and enjoy my new amplifier and midranges. Which if you have an l100 i strongly advise and upgrade to 104h's
    If you're trying to run it as a ported system, you have to make sure the airflow through the port on the inside of the cabinet is unrestricted. Allow 3"-4" minimum clear space all 'round the inside end of the port. Same goes for getting up against any of the moving parts of the woofer, including the tinsel leads. Use cheescloth stapled back as appropriate to hold the insulation.

    Also, try fiberglass inside of polyfill. It just plain works better. And use only long-strand fiberglass -the short stuff can get into places it shouldn't, like the voice-coil gap-

    Filling or stuffing the box adds virtual volume -up to 30-40%, which will tame the peak and lower the cabinet tuning -which helps in either case, ported or A-S.

  3. #48
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Rudy Kleimann
    I find it surprising that BBPRO says the 123A in the cab is a good alignment. We all know it is not just by listening to them. Sure you didn't miss on your measurements or your math? On a box that size, a little means a lot re: percentage of volume change.

    The A-S "Q" is too high, as you can see and probably hear. That is why I said the box is too small for either, really, IMHO.
    BB6P wants bigger for Q = 0.707, yes.

    I'm just exploring, given the box size of L88 and/or L100, which alignment is "better." I outlined elsewhere here how one might build an improved closed-box version using 123Ax per BB6P suggested volumes.

    Part of this also comes from wondering what's being done with all those 123Ax woofers dumped on the market by chop shops over the last couple of years. :dont-know

  4. #49
    RIP 2011 Zilch's Avatar
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    L88 Damping, Box Fill. Closed Port.

    R21 is high-density fiberglass insulation, 6" thick. It's what I had on hand here, purportedly better than normal density for this. Added benefit is I now have two densities in the box, each presumably optimal over a different frequency range.

    Impedance, phase, and nearfield (~1/4") frequency response, before and after installation of fill augmentation.

    Black cone 123A woofer:
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  5. #50
    RIP 2011 Zilch's Avatar
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    White cone 123A woofer and both overlaid, bottom.

    Tamed 'em both 1.5 dB @ 80 Hz.

    Lowered Qtc 0.07 and 0.13.

    Qs now matched within 0.05.

    Lowered Fc of both ~3 Hz.

    Fcs now matched within 0.09 Hz.

    Leveled notch @ 240 Hz.

    MF unaltered, looks like.
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  6. #51
    clmrt
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    Right now, this is my favorite thread on the intraweb.

    Call me when we get into Aperiodic vents.

  7. #52
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by clmrt
    Call me when we get into Aperiodic vents.
    Empiricism is the path to enlightenment. Get to WORK!

    Quote Originally Posted by SETriode
    Stuck some poly fill inside my l100 cabinet today after installing my 104hs and I wasn't too impressed.
    Isolate the variables. Measure. Learn. RTA's a good start.

    Just look at what that woofer's putting out in the upper midrange:
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  8. #53
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Phil H
    Zilch,
    I was curious if the black woofer in the L88 has a folical with a model number. Was there a 123A without the -1 or -3?
    Nope, identical to rotormotor's. Surprisingly, the white one's the same, no foilcal or serial number. Only ID is the part number stamped on the cone. Both have intact red wax seals:
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  9. #54
    Senior Member SEAWOLF97's Avatar
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    Quote Originally Posted by Zilch
    Note port closed for acoustic suspension bass using Zilch's proprietary box tuning device.
    I am getting to know the Ed May designed Marantz speakers (having bought 2 pairs in the last month)..Marantz addressed the port issue with a "Vari-Q" foam plug. The instruction was to plug the port on lower powered receivers. It has a metal rod thru it with 2 larger end caps. You tighten them to expand the foam for tight fit. It rots away just like L100 grills. Maybe a pair of rolled socks (white) would work as well....
    I'm getting tired of Winning ....

  10. #55
    RIP 2011 Zilch's Avatar
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    The genesis of a PRODUCT concept, perhaps?

  11. #56
    Senior Member SEAWOLF97's Avatar
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    Quote Originally Posted by Zilch
    The seed of a PRODUCT concept?
    Darn, you are good Zilch , gotta go foto some of my socks for eBay auctions before you all do.....

    Need a catchy name...maybe "The ZilchWolfMaster 2000 Precision Port Adjuster" ?? ,,,,,,,,,,welll, maybe not.

    Geeze we could get them in different colors to match grills and maybe make enough $ for those Everests with your name on them ??

    (we can even advirtise the propriatory folding technique , and how you void the warranty if unrolled to steal the trade secret)
    I'm getting tired of Winning ....

  12. #57
    RIP 2011 Zilch's Avatar
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    125A and 127A play nicely acoustic suspension in L40's 1.6 cuft box, below.

    Measurements (middle):

    Nearfield driver only orange.
    Nearfield with 3120A filter red.
    Full range orchid.

    BB6P indicates usable bass (-10 dB) available down to ~32.75 Hz, bottom.

    These alignments can take advantage of boundary reinforcement for noticebly better extended bass. I don't know about everybody else, but that's how I typically use bookshelf speakers anyway.

    Footnote: Pooched tweeter dome doesn't affect the sound.

    [It ain't connected.... ]
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  13. #58
    RIP 2011 Zilch's Avatar
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    C36 Viscounts assembled in another thread using two different L100 woofers:

    http://audioheritage.org/vbulletin/s...814#post131814

    More info this thread:

    http://audioheritage.org/vbulletin/s...371#post126371

    These 3 cuft. box plans are here:

    http://www.lansingheritage.org/image...-c39/page2.jpg

    [Merely neglect to put in any port.... ]
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  14. #59
    RIP 2011 Zilch's Avatar
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    A second 2213 over-excursion. I'm not doing this, folks.

    In fact, I think closed-box alignment affords some protection against woofer damage like this.

    Voice coil jumped out of the gap, either coincident with, or after the cone failed (bottom).

    Of interest, perhaps, it's flatwound.... :dont-know
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  15. #60
    Senior Member Fred Sanford's Avatar
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    L46s in an HT environment- benefit from a port plug?

    Hi Zilch- not sure if there's enough info available to you to simulate this situation & come up with any opinion, but I've got six L46s slated for my 5.1 surround setup, and since I was at the Depot yesterday purchasing plugs for my L100s, I picked up two 2" plugs as well that would fit a test pair of my L46s.

    My thought was that, in an HT environment (where there's some serious dynamics, but a dedicated sub for 80Hz & under), the L46s might have a happier, longer life (suspended animation ?) with the ports plugged.

    Driver is a 117H-1, not sure of the interior volume of the cab, I'll poke around or take some rough measurements if this intrigues you in the least.

    Thanks in advance,

    je

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