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  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
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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
    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

  10. #10
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Steve Gonzales
    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 suppose that the horn needs to work within the scale of the L220 also? If not there are several possibilities. If you are after great sound first and fitting it into the L220 second, I'd look at the Edgar salad bowls or perhaps even Johnny's thread on 1" Smith horns... You could certainly make a 1.5" version.

    Widget

  11. #11
    RIP 2011 Zilch's Avatar
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    Two units 2435HPL on PTH waveguides

    24 dB filter at 500 Hz only:
    Attached Images Attached Images   

  12. #12
    RIP 2011 Zilch's Avatar
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    Giskard's earlier post on this subject:

    http://audioheritage.org/vbulletin/s...age=13&p=44426

  13. #13
    Steve Gonzales
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    how about these?

    I spyed these waveguides, they look more to my liking, I wonder if they could be lengthened to go down to 800hz. As you can see, I want the darn things to work in the L220's behind the L94, and you already KNOW I don't care if it sticks out the back!. According to another spec sheet, the 2435HPL is crossed at 1k in the Vertec array's they are installed in.

  14. #14
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    Hi Zilch

    - Nice RTA pics of the 2435 on your waveguides.

    - FWIW ; I don't see anything that would lead me to believe those 2, 2435(s) are "off-spec" . Given the vertical scale you are using they are really quite linear between 1K and 8K . The @ 10 db per octave roll-off after 8K might be dissappointing - but even that slope is quite consistant between both units.

    - I agree that the 2435 on your waveguides / with your crossover set to a 500 hz hipass / doesn't support much of anything below 1000hz.

    - Now the question is really, why ? Here are a few suggestions for testing to narrow down the variables ;

    (a) The 2435 needs to be tested on a horn that handily supports at least 600 hz to give the driver half a chance of loading the lower frequencies ( given the tight backcaps ) .

    (b) The waveguides should also be tested/calibrated with a driver that is known to have significant reproduction down to 500 or 600 hz . That'll help determine where those waveguides' loading limits are .

    (c) And last but not least ;

    - The choice of a 500 hz hipass point for your pink noise test .

    - This part of the test needs to be calibrated so that it's not a contributing variable . So :

    (i) Plug a pink noise source into your electronic crossover .
    (ii) Plug the hipass output of the utilyzed channel directly into one of the input chnls on your Behringer RTA/EQ .
    (iii) Select this chnl as the "input source" while that EQ is in the RTA mode .
    (iv) Get a working level of some observable pink noise .
    (v) Assuming your crossover is variable in frequency , turn the frequency select knob to lower the frequency until 800 hz is about only .25 db lower than a similar measurement taken 1 octave above it . This is the point where the selected hipass point is starting to show a visable effect. ( ie some slope is manifesting itself ).

    - I just did a calibration ( on a Behringer 2300 ) and found that a 250 hz point was about the highest acceptable point to test for 800 hz loading . Choosing any crossover point higher, was noticably attenuating 800 hz within the "stop-band" ( as seen on the RTAs' line input ) .


    All the above variables can be contributing factors in the roll-off below 1000 hz. Each can "skew" conclusions about the 2435s ability to handle lower frequencies than 1000hz .



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