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

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    RIP 2011 Zilch's Avatar
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    Quick & Dirty 4430-Inspired Two-Ways Part I

    1) Take B380 w/2235H set vertically on "foot"
    2) Mount 2344A w/2426H/J on top
    3) Cross @ 1 kHz w/CD compensation (M552)
    4) Biamp

    Something I'm missing here?

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    Senior Member stevem's Avatar
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    No, I think you got it. I have something similar I want to sell. Its a 2235H in a veneered 5 cu ft vented enclosure, with a 2426H and 2344A perched on top. I also have high quality cloned passive crossovers (big air core coils and PP caps). Any idea where I can find a buyer (besides ebay)?

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    Administrator Robh3606's Avatar
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    3) Cross @ 1 kHz w/CD compensation (M552)

    Yes the CD comp doesn't work plain and simple. You need an EQ in that last octave. For PA yes but not at home. The passive network compensation is simply the best alternative and it's cheap and easy to build.

    Rob

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    RIP 2011 Zilch's Avatar
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    All RIGHTY, then.

    Quote Originally Posted by Robh3606
    The passive network compensation is simply the best alternative and it's cheap and easy to build.
    The schematic is here:

    http://www.jblproservice.com/pdf/Stu...ies/4430LR.pdf

    I see the subject MF attenuation (L-pad R202 and series R4) and HF bypass (R201 et.seq., 13.5 kHz?) Curiously, in biamp mode, a first-order filter (C7, 20uf, 1000 Hz?) switches in in lieu of second-order (C11, L2) internal passive mode filter. C7 merely provides phase inversion with external crossover, no?

    The conjugate filter stays in the LF circuit, as well. Hmmmmm.

    The 4430 spec sheet says use 5235 with special board, or, if not, 12 dB/octave at 1 kHz.

    Any insights here? Haven't I also seen 5234A with 4430 boards, or are those DIY?

  5. #5
    Administrator Robh3606's Avatar
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    Hello Zilch

    Ian had a couple of good post's in this thread have a read.

    http://audioheritage.csdco.com/vbull...4430+crossover

    That 20uF is one of the poles in the filter and is neccessary when used with the JBL crossovers. The cards are 18db cards not the 12db you would expect. I have a 5235 with the 4430/35 cards same as the 5234 cards.

    Rob

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    RIP 2011 Zilch's Avatar
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    I do have a pair of "new" N3134 networks, which I'm going to use to convert a pair of L200's into quasi-4430's, assuming I can make the horns fit. Don't know if anybody here has tried that.

    Not sure if I'll change out the LE-85 diaphragms to D8R2425 or just pick up some 2426H's to use, maybe both, for comparison. Depends on what the LE-85's are worth at the time, probably. I'm a little concerned about the baffle angle of the L200's; 2344A in 4430 tuning wants listener on-axis or above, unless that's just BS in the brochure.

    Thought I'd try this proposed B-380 "stack," as well. Mackie M1400i has "Constant Directivity" compensation that seems to match what Giskard and Ian posted as being required. JBL M552 has something similar, though I haven't seen the curves yet:

    "Constant Directivity horn pre-emphasis allows for smooth, flat frequency response from JBL 2360 Series and 2380 Series Flat-Front Bi-Radial horns, or other CD horns."
    It's 24 dB Linkwitz-Riley filters. We'll see. Gonna take an RTA to assess what's going on with these "projects," probably....

  7. #7
    Administrator Robh3606's Avatar
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    Hello Zilch

    That's a cool idea. You are going to need a 1" spacer board under the 2344 to give it the same baffle alingment as a 4430. I use the M553 with my 2344's and the curve you get is listenable and measures fairly well but after 10K you get a good bit of roll off. The passive network does a better job up top and gives you a way to trim the response which you won't be able to do with the canned CD curve in the M552/553. The Le-85 should work fine figure the original 4430 had 2421's in there. You could go with the 2421 diaphrams but they are rather expensive.

    Rob

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    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Robh3606
    Hello Zilch

    That's a cool idea. You are going to need a 1" spacer board under the 2344 to give it the same baffle alingment as a 4430.
    Well.... what about the sloped baffle? I personally don't think the "Time Alignment" is what makes the 4430s sound good, so it probably won't matter.

    Widget

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    Senior Member Ian Mackenzie's Avatar
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    The 1'' baffle space optimises the smooth crossover transition at 1k Hertz.

    Ian

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    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Robh3606
    The passive network does a better job up top and gives you a way to trim the response which you won't be able to do with the canned CD curve in the M552/553.
    So, is biamping 4430's a worthwhile endeavor at all if you need that passive EQ for the VHF that's in the network for it to work optimally?

    And, if so, is there a preference for 5234, 5234A, or 5235 to use with the 4430 cards to do it? Those are 18 dB cards, as I understand it, plus the 1 pole the remains in the passive, makes 24 dB filters, which will be different, at least, from the straight passive use. Enough so to matter?

    I've certainly seen posts here attesting to 4430's REALLY shining when properly biamped, tho I've never done it myself. I like 'em plenty good just running passive....

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    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by stevem
    I have something similar I want to sell. Its a 2235H in a veneered 5 cu ft vented enclosure, with a 2426H and 2344A perched on top.
    Post 'em here in "Marketplace" first with some nice pics. The forum is getting regular traffic these days....

  12. #12
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Ian Mackenzie
    The 1'' baffle space optimises the smooth crossover transition at 1k Hertz.

    Ian
    Agreed. If measured from the correct listening height.

    My point was that since the L200 cabinet has a sloped baffle it changes the relative distance between woofer acoustic center and HF acoustic center.

    Come on Ian, keep up.

    BTW how is the crossover coming?

    Widget

  13. #13
    Senior Member Ian Mackenzie's Avatar
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    The 443X are designed for a 15 degree upward tilt on verticval polar axis for inverted mounting, according to my rather dog eared white paper.

    Zilch, some tweeking will be needed and access to a gated test set to result in the smoothest transition in the crossover region. The JBL network was optimised for that driver layout only.

    Regards the tilted baffle why not if you wish, the design is supposed to give even power response on a 100 degree arch.

    The biamping can be done with other than the 5234/5 JBL networks if you like bi amping but be prepared to fiddle a bit. If you use the JBL passives it would be a good place to start imho
    .

    Either way it will be vastly superior to the L200 combination.

    You are in for a treat.

    Ian

    PS. The Widget or John F should start carving Bum horns, and if theres a demand I will make a hi fi crossover and mini class A amp for the 2426/2344 and retire..LOL

  14. #14
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Robh3606
    The Le-85 should work fine figure the original 4430 had 2421's in there. You could go with the 2421 diaphrams but they are rather expensive.
    Indeed, the mighty Giskard suggested in an earlier thread, (the genesis of the L200/4430 conversion idea):

    "Change the diaphragms to D8R2421's or D8R2425's and let 'em rip."

    2421's are diamond surround aluminum, and 2425's are titanium?

    What's the difference between 2425 and 2426 drivers, then?

    M552 bought on eBay came today, sans manual of course. It appears the "Constant Directivity horn pre-emphasis," whatever it actually is, is there whether you want it or not; I don't see any way to switch it in and out.

    Anybody gotta M552 manual they'll copy for me so's I don't have buy one from JBL?

    Thank you Ian for the encouragement. If I can work all of this out, converting L200's into quasi-4430's may be a good option for others here. I'm gonna be tryin' the P-Audio horns, as well, as soon at TimG and Widget test them. Guido's earlier work here indicated they were a viable, if not superior, alternative to 2344A's. Thinking I may bring in a couple of skids of them so's they'll be cheap for everyone to try....

    The adapter dropping them down from 1.5" to 1.0" adds a couple of inches to the depth, messing up the time alignment, probably. With 24 dB/octave filters, it may not matter. What the Hell, we'll figure a way to tweak it, if necessary. As Widget suggests, it may be only a minor factor in what we like about 4430's, anyway....

  15. #15
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    Anybody gotta manual they'll copy for me so's I don't have buy one from JBL?
    [/QUOTE]I have the 552 manual and could make a copy and fax it if you like.
    chuck

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