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Thread: Mini DIY

  1. #91
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    I finally got to listen to Zilch's mini-4425's today, (mine are still in the construction phase), and have to admit - they sound pretty good! While bass is somewhat rolled off at the very low end, they're surprisingly smooth sounding speakers. Hopefully, mine will be together soon, and we can see how ported 115H-1's sound compared to Zilch's sealed 8 inchers... The high end is definitely really nice and smooth.

    John

  2. #92
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    BB6P says I should be doing better at the low end than I am, with usable bass down to 36 Hz. I'm up around 45 to 50 Hz right now, according to the nearfield measurements (above).

    It's difficult to find 116's (A or H) with ACTUAL Fs = 28 Hz, as many have been refoamed, and I suspect the spiders are now stiff, too. Looks like recone's the only good answer.

    Audivex is helpin' me with that.

    [Still gotta tweak the box damping, apparently, too.]

    In the meantime, they're mighty pleasurable listening....

    See Dickason's LDC6 Studio Monitor project in Loudspeaker Design Cookbook for more on the closed-box design approach to Minis.
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  3. #93
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    I've been working on putting my 4425 mini's together this weekend, but remembered I had some pics of putting Zilchs' cabinets together.

    I cut out parts for 5 cabinets, (1 spare just in case). These were made from 3/4" birch ply, with full mitered corners and rabbeted fronts and backs. But after the hassles of dealing with cutting and gluing up clean miter joints, I'm going to the nail gun and veneer from now on.

    The first pic shows the parts for 2 cabinets, including the extra pieces for adding the additional baffle depth behind the horns.

    The second pic shows the clamps required - I used even more on the next cabinet!

    3rd pic shows the raw cabs, front and inside, before mounting and trimming the extra horn baffle.

    4th pic shows the completed cabinets, (backs removed), ready for staining and components. Zilch has already posted pics with his components installed, and JohnW was kind enough to provide us with really nice foilcals for the finishing touch!

    I think I'm going to leave my pair in plain birch finish, with a clearcoat. Using the JBL bule grillecloth, I think they'll look pretty modern/contemporary. I'll be trying both 115H-1's and 706G-1's, (as in L1's, etc.). The 706G-1 actually looks to have a slightly larger magnet.

    I'll post pics when I finish mine, but I'm sure it'll be at least another week. It's 113 degrees in my yard today, and 90 inside - 'way too hot to do much work - I can barely sit here and type...

    John
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  4. #94
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    There was a recent post in these forums regarding design of Project Array discussing that the slot orientation was selected based on the fact that pattern control and smoothness in biradial horns was not as good from the diffraction component as from the radial, and since horizontal dispersion was more important than vertical, the slot should be oriented accordingly, i.e., sideways.

    That tells me that the optimum orientation should be as shown below, yet in Project Array, the slot is oriented "in the vertical plane," according to the text descriptions. I can't see it (the slot) in any of the photos. Can someone link to the post I'm referring to, please? I cannot find it now, of course....

    The 2404H spec sheet seems to indicate that this "hourglass" orientation is, indeed, better. I THINK the beamwidth chart shows vertical is flatter above 5 kHz, tho I can't quite read which is which there:

    http://www.jblpro.com/pages/pub/components/2404.pdf

    The off-axis response drops off more quickly beyond 45° in the vertical, which would reduce (attenuate) sidewall reflections when the horn is rotated 90 degrees, and would seem to be the better orientation so long as the floor is not reflective.

    No?
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  5. #95
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    Zilch ;

    There was a recent post in these forums regarding design of Project Array discussing that the slot orientation was selected based on the fact that pattern control and smoothness in biradial horns was not as good from the diffraction component as from the radial, and since horizontal dispersion was more important than vertical, the slot should be oriented accordingly, i.e., sideways.

    That tells me that the optimum orientation should be as shown below, yet in Project Array, the slot is oriented "in the vertical plane," according to the text descriptions. I can't see it (the slot) in any of the photos. Can someone link to the post I'm referring to, please? I cannot find it now, of course....
    - I'm pretty sure that somewhere you've misinterpreted G.Ts' words ( plus I believe you may be mixing planar horn surfaces ( conical ) into your thinking .

    - I've always found that the 2344 measures better in the horizontal axis ( with vertical slot ). For instance ; 16Khz does a great job diffracting past that fairly sharp edged vertical slot .

    - Don't know the referenced thread offhand / though , I may look it up for you / use your CLIO to settle the question .



    BTW ; cute little speakers you guys are making / very nice .

  6. #96
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    Quote Originally Posted by Earl K
    BTW ; cute little speakers you guys are making / very nice .
    Thanks, Earl.

    Would only you could hear their ground-shaking bass and window-shattering highs!!!

    [Heh, heh.... ]

  7. #97
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    LE8T-H gets a final old college try. Kinda dull, clinical-sounding, like music appreciation class. Usable bass (-10 dB) only down to 48.6 Hz. They want plainsong played through them, not R&R.

    Minis should be "ballsy," I think. 116H-1 (pic in #94, above,) certainly gives them that in these small closed boxes. Qtc is downright embarassing. [Think L100.... ]

    Also tried perf-frame HTI8 woofers with butyl surrounds and coated aluminum cones. They're fine, but the stamping is made for rear mounting which also seals to the surrounds. I'd have to devise some custom rings and clamps to install them confidently from the front. Nearfield LF response reveals them as a compromise between LE8T-H and 116H-1.

    HTI8 crossover (bottom, left) is symmetrical 18 dB/octave at 2.5 kHz and works well. Ordered parts to build up a pair with better caps and coils. It buries 116H-1 response anomaly at 3.5 kHz; no supplemental notch filter required.

    Same circuit as Control 128W here: http://www.jblproservice.com/pdf/Con...rol%20128W.pdf

    I'll post the revised schematic and parts list with tweaked Zobel and 2404H(-1) attenuation after testing my DIY version. Maybe I charge-couple the HF, too....
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  8. #98
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    Exclamation Thread Hi-Jack


  9. #99
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    Way COOL, Giskard!!

  10. #100
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    Man, that Knucklehead sounds better than my Twin-Cam.
    There are two theories to arguing with women, but...neither has worked.

  11. #101
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    Re: My post #94, above, here's the citation:

    http://audioheritage.org/vbulletin/s...2&postcount=12

    [Lemme read it again. ]

    O.K., I'm still confused by this. K2 slot is horizontal. Diffraction controls the vertical dispersion like in Smith horn, no? This would be optimal.

    Whereas, in 4430's 2344(A), the slot is vertical, and the diffraction controls the horizontal dispersion, i.e., not optimal, according to the theory.

    I'm also thinking about PH-316 studies (also vertical slot,) where rotating the horn 90° gives better (more controlled) horizontal polar response.

    "What Greg Timbers discovered is that the diffraction slot is more effective in maintaining uniform polar and amplitude response in the vertical plane than the compound geometry is in maintaining uniform response in the horizontal plane."

    That's with a horizontal slot, then? The straight edges of the slot are doing (controlling) the dispersion? :dont-know

  12. #102
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    Best sounding of the 3 motors.

    Quote Originally Posted by Hamilton
    Man, that Knucklehead sounds better than my Twin-Cam.
    Wonder how much it would cost for one of them motors???

    Ron

    PS: sorry for OT!

  13. #103
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    Quote Originally Posted by spkrman57
    Wonder how much it would cost for one of them motors???
    Alot - http://www.replicaengines.com/

    Quote Originally Posted by spkrman57
    PS: sorry for OT!
    Yeah, Zilch's photo of the LE8 reminded me of how many of them I killed running them in the rear decks of various daily drivers back in the 70's.

  14. #104
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    $7200 for Aurora V8

    Neat as hell though!

    Ron

  15. #105
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    18 dB/octave factory HTI 8 crossover, left.

    Biased HF DIY version, right.

    Circuit sim voltage drive, bottom.

    Maybe Earl'l tell us what's going on there.

    Kinda silly puttin' all this effort into Minis.

    ['Til ya hear 'em.... ]
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