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Thread: JBL 2435HPL's

  1. #1
    Steve Gonzales
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    JBL 2435HPL's

    Hello,
    I won some brand new JBL 2435HPL's today!. I want some suggestions for a horn that will be suitable for an 800hz crossover point. I've looked at the JBL Pro site and it shows a "wave guide" horn. I am thinking about modifiying an H92/2312 to fit the 1.5" throat exit. Idea's anyone?. I looked at the tech sheets on this driver and am drooling over the possibilities as one of the finest midrange drivers on the planet. I realize that this is an underkill use for an overkill driver but, I couldn't HELP MYSELF! I am going to use them in my L220's with the L94 lens for starters and see what THAT sounds like. I sold my 375's and put the money into these amongst other neat toys (JBL). I have NO idea how to calculate the flair of a horn to work with a compression driver and I do hope someone out there is willing to help. I will say THANK YOU now. Talk to ya later, Steve G

  2. #2
    RE: Member when? subwoof's Avatar
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    Hey there...I modified some 2307's for a 1.5 driver ( also have a pair of 2435's ) and here is the description. The pix are long gone from my website so I need to look for them though.

    Getting 800 Hz is going to be a real problem due to horn length. The JBL horn 2332 ( as used in the DMS1 monitor ) is the best choice ( although it's a 1K horn ) and it's footprint will closely match the L94's in that cabinet.

    I also have a couple of ASC24 crossovers that were designed for the pro 14/1.5 combo ( array series ) and would bi-amp those cabinets well with some small corrective EQ ( the driver + cone are a little different )

    Then it will look + sound like the $20,000 japanese models and you can sell the cats eye tweets and retire...

    http://audioheritage.csdco.com/vbull...highlight=2313

    sub

  3. #3
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    Hi Steve

    A couple of things ;

    (1) 800 hz Crossover Point :

    First & Foremost ; You'll need to determine if the 2435 actually supports the 800 hz crossover point. The extremely tight fitting backcap may prevent proper production & propogation of these lower frequencies. I'm under the impression that typically the 2435 and its siblings are all used above 1000hz. I might be wrong though . You might see if you can get Zilch or Widget interested in assisting in the determination of this question. ( ie. the lower limit for these new 3" diaphragmed drivers) They have the necessary measuring tools.

    (2) Horn ;

    (i) I guess you could convert a 2312 to accept a 1.5" exit driver . You'd do this by sawing through the throat at the point where it is 1.5" in diameter ( and then building a new mounting flange ). For this horn to even partially load 800 hz, it needs to have a throat length that is equal to at least 1/2 of the length of the 800 hz waveform. That equates out to a distance of @ 8.5" necessary depth, ( measuring from bell exit back to drivers phaseplug ) .

    (ii) Another option (the one I would try first ) is to simply take a 2307 horn and reverse-fit the 1.5" to 1" adapter onto it. There's no reason I can think of why not to do this, given that you are adding a tweeter overtop of this setup. JBL sells a 1 to 1.5" adapter. It's part number can be found somewhere in Ziches Q & D 4430 thread ( multipaged tome ).




  4. #4
    Steve Gonzales
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    could be..

    Earl, I was thinking of taking a 1.5" to 2" adapter and having the 2" end flange turned down to approx. 3/16" under OD and notched back 3/16" , then taking a 2312 and cutting it at the point where it reaches 2" and have that end milled out the negative of the adapter end. Just off the top of my head, I believe that this would give me the length that I need to support the 800hz crossover. I'll have a look at the other 2435 threads and see if it can safely play down that far. Thank you for answering the wave length question for me, I did'nt know that formula. Thanks to subwoof too. I remember seeing the original pictures of that horn mod.

  5. #5
    Senior Member Ian Mackenzie's Avatar
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    Why not look at some of the JBL PTwave guides, cheap and made to measure and Zilch has been exploring applications and crossovers.

    Far more recent technology and tested by JBL with such drivers as I recall.

    Suggest you hook up with Zilch and copy in on the Intel.

    Ian

  6. #6
    Senior Member herve M's Avatar
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    "I'm under the impression that typically the 2435 and its siblings are all used above 1000hz. "
    No problem for 3 in. diaphragm compression driver!! JBL use 2430 in 4622 (700hz for passive network, 500hz in active crossover). In 4350 , 1200hz for 2440


    "The JBL horn 2332 ( as used in the DMS1 monitor ) is the best choice ( although it's a 1K horn ) "

    Yes, I use 2430/2332 with DMS1 curve by DSC280 active crossover. Fantastic !!

    HerveM

  7. #7
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    No problem for 3 in. diaphragm compression driver!! JBL use 2430 in 4622 (700hz for passive network, 500hz in active crossover).
    - Thanks Herve ! You made me download the cut-sheets & take a quick gander .
    - Anyone else interested can download this JBL info on the 4622 here.


    According to that sheet ( & for the included 2430h driver in that model ) :

    - Passive Xover point is set at 750hz .
    - Electronic Xover point can be as low as 630hz, as implied by the info sheet.

    NOTE :
    - I'd still be somewhat wary of the wholesale application of this info to the 2431H & 2435H models without additional testing or some more application notes from JBL .


    <

  8. #8
    RIP 2011 Zilch's Avatar
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    Posts by Giskard in the "Q&D 4430's" thread suggest that the back cap of 2435's must be replaced in order for them to play down to 800 Hz, which they will do nicely. I have no clue yet as to the part number or source for the deeper back caps. That's Project May territory....

    If you won those 2435's on eBay from the seller currently listing them in the $500 range with misinformation about their retail price in the listing, be aware that the pair I bought from them will likely be going back to JBL for repair after we complete testing them, as my 2431's (one of THEM suspect, as well) have better frequency response.

    We're still waiting for receipt of additional 2431's before we test all of the drivers together. The spec sheets for 2431 and 2435 are not available outside JBL, apparently, so we have to develop this information ourselves.

    To use them on PT Waveguides, which are constant directivity, you'd likely be abandoning the L94 lens. I'm not familiar with the 2332, but several forum members have used them in their projects. The L220 Tech Sheet shows the effect of the L94 lens on LE5.

    I'd have serious reservations about reducing an exit diameter with an adapter. Maybe go the other way and adapt up to the 2" stubby H93 horn instead? You really need some test gear. There's no way to reasonably accomplish anything by random action with this stuff, I have learned, and anything you DO accomplish is suspect otherwise....

  9. #9
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    Quote Originally Posted by Zilch
    The L220 Tech Sheet shows the effect of the L94 lens on LE5....
    That's Zilch's cue to me to get crackin'

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    RIP 2011 Zilch's Avatar
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  11. #11
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Zilch
    If you won those 2435's on eBay from the seller currently listing them in the $500 range with misinformation about their retail price in the listing, be aware that the pair I bought will likely be going back to JBL for repair after we complete testing them, as my 2431's (one of THEM suspect, as well) have better frequency response.

    Better Response? Do you mean flatter in the mid band as Steve would be using these in modified L220s with the Cat Eye, or do you mean more extension up top as needed for your two-ways?

    The PT waveguides would certainly physically fit the L220 mod project, I am concerned that the ones that Zilch has tried have all been a bit anemic at the low end. Will any of them go below 800Hz for a solid 800Hz crossover?

    As for bigger back caps I think they would need to be custom fabricated. As far as I know the only ones made by/for JBL are the 435Be/435AL back caps... I doubt these are available. It shouldn't be too difficult to make some from PVC pipe and a bit of plastic sheet stock.

    Widget

  12. #12
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Steve Gonzales
    Earl, I was thinking of taking a 1.5" to 2" adapter and having the 2" end flange turned down to approx. 3/16" under OD and notched back 3/16" , then taking a 2312 and cutting it at the point where it reaches 2" and have that end milled out the negative of the adapter end. Just off the top of my head, I believe that this would give me the length that I need to support the 800hz crossover.
    I do think you would be pleasantly surprised if you try other horn designs... but rather than going to the trouble and expense of the above machining why not bolt a 2330 (1.5-2" adapter) to a 2311 (2" version of the 2312)?


    Widget

  13. #13
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Mr. Widget
    Better Response? Do you mean flatter in the mid band as Steve would be using these in modified L220s with the Cat Eye, or do you mean more extension up top as needed for your two-ways?
    I was lookin' at extended HF, of course, which they're supposed to have over the 2431's, but now I forget the test conditions. I'll hook 'em up again here and see what the RTA says, maybe tonight, on PT waveguides.

    In a week or so, we may be able to do something more precise.

  14. #14
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    Earl, I was thinking of taking a 1.5" to 2" adapter and having the 2" end flange turned down to approx. 3/16" under OD and notched back 3/16" , then taking a 2312 and cutting it at the point where it reaches 2" and have that end milled out the negative of the adapter end.
    - Frankly , I just wouldn't bother cutting metal ( like your 2312s and any available 1.5" to 2" adapters .

    - The 2307 is 8.5" deep on its' own . That throat length alone supports the 1/2 wave criteria for 800 hz ( though the mouth circumference does not ). The addition of a 1.5" to 1" adapter adds a little bit more LF loading. The addition of the serpentine-fins from the H94 effectively increases the length of the 2307 horn plus also increases the overall mouth circumference. So, if the stock 2435 has linear-loading down to 800 hz then the 2307/L94 will support it at those frequencies . But it's up to the 2435h to do its' part.
    ( Take a look at the available 4622 pics to get an idea of just how "oversize" a horn needs to be when a driver is restricted in it's ability to "do its' part" in the lower reaches. )

    - Regarding JBLs' newer Waveguides :

    (i) My advice ; buy one (or borrow) and take a listen to it . IME : JBL has traded-off quite a bit of lower-midband loading for the realized increases in HF extension.. This is what the SR market wanted & this is what it got. Changing that loading changes the dynamic curve of the combo and its' propagation authority in the midband area ( I'm not saying for good or bad - the older 2426H had maybe too much torque below 1K for "easy" HiFi reproduction ). What I am saying, is that when a system tweeter is a given - be careful about what technological compromises you are prepared to buy into . "New" does not necessarily equate to "slam-dunk" better when integrating these newer parts into an older system such as yours.



    PS :
    - I see the Widget has weighed in with the 2311/2330 combo / it might work . I'll need to test the 2308/2311/2330 combo ( on a Europeon 3" diaphragmed driver ) . Just be aware - the hole pattern for the 2330/(or its' Selenium equivalent) doesn't matchup to JBLs' newer 3" diaphragm drivers .
    - I see Widget & myself appear to be in agreement , ( re; his remarks about "anemic midband performance" ).

  15. #15
    RIP 2011 Zilch's Avatar
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    Hi, Earl,

    Do you agree that an L94 lens would not be appropriately applied in front of a constant directivity horn?

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