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

  1. #361
    RIP 2011 Zilch's Avatar
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    Build them for your rear channels, then.

    And spin your chair around when you want to listen to jus' them!

    [Gotta have more than ONE system to play, anyways....]

  2. #362
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    Hi Zilch

    Along with Guido's PTH waveguides, a new pair of 2431H drivers came in. I mounted them in the modified L200's on PTF waveguides. No EQ, just the AM crossovers we're using, here's the performance, L & R:
    - Nice matched set of drivers .

    - I'd like to see what they can do on a 650 hz horn with a low crossover point . Do you have any horns like that ?

    - A quick suggestion ; I just spent about 10 minutes using the search engine to try to find ( within this thread ) the technical info that relates to your "AM" crossover reference . Maybe for the rest of us, you could note what post that info is found in so we can follow along . Thanks !



  3. #363
    RIP 2011 Zilch's Avatar
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    Hi, Earl.

    "AM" crossover refers to HF section of AM6212/00, the JBL product which uses the 2431H on PTH (12" X 12" square) waveguides, but in combination with the LF section of 4430's N3134. Guido's building with 4435's N3135 LF.

    I put together a parts list here:

    http://audioheritage.org/vbulletin/s...age=21&p=48600

    Note that R1 and L4 values are a little different in the HF section; we're using what actually came on the factory crossovers to start, which are not what's on the schematic:

    http://www.jblproservice.com/pdf/AE%...6212,00-WH.pdf

    JBL varies the HF crossover a bit depending upon which version of PT waveguide is used:

    http://www.jblproservice.com/pdf/AE%...6212,64-WH.pdf

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

    The simplest configuration seems to work with the PTF rectangular 100° X 100° waveguide as well, (see most recent RTA plots, above,) though we may be "finessing" them a bit with more experience.

    I'm still using factory crossovers for both sections right now, waiting for parts to come in to complete my own DIY versions, in progress.

    Ooops, there's the UPS guy right now.....

  4. #364
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Earl K
    I'd like to see what they can do on a 650 hz horn with a low crossover point.
    Like 2435H, I suspect they'd require the larger back cap to play worth a whit below 800 Hz.

    I could try them on the P-Audio 2344A clones, which are spec'd down to 500 Hz, but I don't have any true MF horns here for a REAL challenge....

  5. #365
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    Zilch

    - Thanks for the AM update. I'll take a look at all that info this weekend .

    - Now that you've established the HF capabilities of the 243x series / I would love to see just what it can do in the lower regions .

    - One of the reasons I published those RTA pics of the B&C 900 / RCA horn was to demonstrate just how much lower midrange can be obtained when a large horn is used. By the way ; The cut sheet on that driver actually recommends a 1200 hz point ( at 12 db / octave ).

    - Considering the 2431s' top end extension , I'd love to see what those 2431Hs are capable of on the H9800 . That would be a reasonable test / even with the tight back-cap . How about you and the Widget hooking up sometime in the future to suss this out ( or is the H9800 travelling ? ) Anyways

    chow <>

  6. #366
    RIP 2011 Zilch's Avatar
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    Work in progress:

    1) DIY crossovers, nearly complete, await delivery of a few coils from Parts Express. N3134's (top) incorporate full original switching plus Zilch's new "Biwire" option using available 6th switch pole. AM version (bottom) for upgraded L200's is way simpler.

    2) Switches for N3134 are prewired using 18 Ga. (16/30) hookup wire; 12 leads total required. They made construction a decidedly non-trivial endeavor. I had to break out the magnifying visor to build them, and it took over an hour apiece to do it. Wire colors denote six different switch functions, so the Zilchster gets the connections right.

    3) Rear of N3134's prior to switch installation (bottom) and after (top). Bifurcated terminal ends (see unwired ones there) permit secure point-to-point wiring. Components are laid out to simplify it and minimize lead crossings, as if it were a printed circuit. 1/8" thick electrical-grade fiberglass substrate will mount on recessed rear panel per JBL convention. Boards are 7" square.

    The input terminals used here are REdiculous. They'll accommodate lead wires the diameter of a pencil.

    [Ordering up more of them for the AM boards, now.... ]
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  7. #367
    Senior Member Guido's Avatar
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    Nice work Zilch!

    So you're not gonna bias the AM's?

    The biased 4313 sounds so awesome that I gonna bias the 3135 and the AM's for sure.

    BTW Horns are locked up in the custom. But no problem I'll get them out soon
    BLS Reference on Passlabs XA 30.5 + Everest DD66000 clone on Pass XA 100.5

  8. #368
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Guido
    So you're not gonna bias the AM's?
    Next project.

    Thought we'd better get these "optimized" first.


    Quote Originally Posted by Guido
    Horns are locked up in the custom. But no problem I'll get them out soon
    Guido's gettin' his PT-H1010HF waveguides.

    NOW this thread'll see some ACTION!



    [Hopefully, he's got his 2431H drivers to go with 'em, too....]

  9. #369
    RIP 2011 Zilch's Avatar
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    L200 Grilles

    Sonofagun's L200 grilles arrived today. Not glued to screens yet, they're just sittin' there lookin' like a million bucks! RTA finds them to be acoustically transparent.

    While the texture is different, of course, the color is a close match to JBL Monitor Blue. Look closely at the closeup pic, and you'll see there's a swatch of factory grille cloth stuck on there for comparison.

    Do we know the JBL Part# of those little plastic pinback logos? It'd be good to save forum members the embarassment of paying $25+ for them from the Orange County reconer guys....

    Can ya hear 'em? That's Brian Ferry's "Frantic" they're playin'....
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  10. #370
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Zilch
    Do we know the JBL Part# of those little plastic pinback logos? It'd be good to save forum members the embarassment of paying $25+ for them from the Orange County reconer guys....
    I have a pair of the original metal logos that are appropriate to the L100 and L200 among other JBLs of the era... If there were a number of members interested in them I could do a run of 20+ and they should be about $5 ea. maybe less.

    Widget

  11. #371
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    Health note:

    See pic in post #366. That's a 50 CFM Comair Rotron "Whisper XL" fan there, $27.40 at Digikey (#CR117-ND), plus $1.79 each for finger guards (2 required, #CR210-ND) and $1.80 for the 3' plug-on cord (#CR371-ND):

    http://dkc3.digikey.com/PDF/T051/1372.pdf

    Virtually silent in operation, it's just powerful enough to pull the solder fumes away without cooling the work. 70 and 83 CFM versions also listed there, same price, not so quiet, probably.

    Ask at the target range if lead fumes are hazardous to your health. There's no sense breathing them directly....

  12. #372
    Senior Member Guido's Avatar
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    Quote Originally Posted by Zilch
    [Hopefully, he's got his 2431H drivers to go with 'em, too....]
    I need to fill my wallet first

    Too many projects at the same time at the moment.

    Buying a house (obviously the most cost effective )
    Biasing 4313 clones
    Building 2203 based Subs
    Building the 4435 clones

    I'll first test the Waveguides on 2426 and 2421 drivers in Ralf's 4430 clones.
    BLS Reference on Passlabs XA 30.5 + Everest DD66000 clone on Pass XA 100.5

  13. #373
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    Quote Originally Posted by Guido
    I need to fill my wallet first

    Too many projects at the same time at the moment.
    You have NO sense of priority.

    NOTHING matters but this....

  14. #374
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    Quote Originally Posted by Mr. Widget
    I have a pair of the original metal logos that are appropriate to the L100 and L200 among other JBLs of the era....
    We'll talk....

  15. #375
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    I've received several inquiries regarding my crossover construction method illustrated above. The push-in terminals I'm using were discontinued and the tooling destroyed 30 years ago. I only have enough stock for my own use presently.

    BUT, I'm trying to round up more from surplus and grey-market sources right now. If there's enough interest, I'll consider making new tooling to produce them....

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