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Thread: JBL 4430 Questions, Please.

  1. #16
    Senior Member Mike F's Avatar
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    Quote Originally Posted by cgregory4 View Post
    "You needed a special 18Db network card for the 5235 crossover. It did not include the CD compensation and if you did a DIY version all active the CD compensation available in typical crossovers is not as good as the passive network."

    In plain English, please!

    I
    Robh3606: I believe the 4430 specific card (52-5130) has a 12 DB per octave slope.
    Greg: CD (Constant Directivity) compensation is a form of high frequency equalization for horns.

  2. #17
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    Thank you, Mike.

    Quote Originally Posted by Mike F View Post
    Robh3606: I believe the 4430 specific card (52-5130) has a 12 DB per octave slope.
    Greg: CD (Constant Directivity) compensation is a form of high frequency equalization for horns.
    I guess I am so far behind the average 'curve' of this forum, I just need a translator like you sometimes!

    Thank you,

    Greg

  3. #18
    RE: Member when? subwoof's Avatar
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    slope, position, et all

    the crossover as designed leaves one pole in the hf side to make it an 18db slope even though an external connection is a 12db slope ( using an abbreviated 18db card in the 523X crossover )..

    So in my experience biamping is somewhat moot on this system but doing a charge-coupled crossover mod is a BIG change...save the money and get a large amp and a pile of solens..

    the CD comp IS still in the path if internal crossover is used ( recommended ) - no matter the switch selection. Look at the schematic before posting please.

    This system used an old style 1 inch compression driver so that is pushed to it's limit with the network so don't expect stadium levels without distortion..larger format drivers work much better for those SPL's.

    But getting them to an acceptable SAF is very difficult.

    sub

  4. #19
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    Charge-coupled crossover?

    Quote Originally Posted by subwoof View Post
    the crossover as designed leaves one pole in the hf side to make it an 18db slope even though an external connection is a 12db slope ( using an abbreviated 18db card in the 523X crossover )..

    So in my experience biamping is somewhat moot on this system but doing a charge-coupled crossover mod is a BIG change...save the money and get a large amp and a pile of solens..

    the CD comp IS still in the path if internal crossover is used ( recommended ) - no matter the switch selection. Look at the schematic before posting please.

    This system used an old style 1 inch compression driver so that is pushed to it's limit with the network so don't expect stadium levels without distortion..larger format drivers work much better for those SPL's.

    But getting them to an acceptable SAF is very difficult.

    sub
    sub,

    Thank you for your comments.

    1. A "large amp and a pile of Solens." Now that's something I can both understand and do!

    2. What is a "charge-coupled crossover" and where would I find one for the 4430?

    3. I am about 12' from the speakers and listen at low SPLs with 250 watts per channel.

    4, What driver would you 'sub' (pun intended ) for the original 1", if you were to upgrade?

    Greg

  5. #20
    Senior Member 4343's Avatar
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    Cool

    Quote Originally Posted by cgregory4 View Post
    ...

    4, What driver would you 'sub' (pun intended ) for the original 1", if you were to upgrade?

    Greg
    The 1" drivers work great, as long as you don't run them too low. The 1KHz crossover is a little low, IMO, as well as being a stretch for the 2235H.

    My home builts are now a 3-way, with a 10" mid to take over the parts that the original drivers struggle with, at least at extreme levels. I only had to replace one cap to get the HF to blend with the mid. IIRC, it was a 4.7 uF (or so) that I reduced to around 4.0 uF to raise the HP filter on the 1".

    I lifted the mid crossover schematic direct from the 4344MkII L/R, and the 10" driver as well, with the upper crossover @ 1.3KHz. I does not look like much, but that 300 Hz takes the strain off the 1" driver enough that I can drive them fairly loud without hearing the telltale sounds of over excursion, which I've learned to avoid. (I managed to keep a set of 2420's with original style aluminum diaphragms alive for 20 years of dances, PA gigs and parties, so believe me, I know what they sound like when stressed.)

    The problem with 2" drivers is that the lose directivity in their upper octave, it's just a matter of physics. Without crossing over to a UHF device, you will get beaming...

    Quote Originally Posted by cgregory4 View Post
    ...
    2. What is a "charge-coupled crossover" and where would I find one for the 4430?
    ...
    Greg
    Also know as a "Biased" network, it requires 4 times as much capacitance at each of the original capacitor locations. You can either use 4 caps of the original value in series-parallel or two caps of twice the value in series. (Or two caps of different values that when placed in series result in the original value.) A DC voltage is applied to the center of the series string via a high value resistor (1-3 Meg ohms), which biases the caps. The idea is that the AC waveform does not ever make the caps go through zero volts.

    There is no stock crossover for the 4430 that is biased, you will have to build one, or find someone that can do that...

    Quote Originally Posted by cgregory4 View Post
    ...

    4, What driver would you 'sub' (pun intended ) for the original 1", if you were to upgrade?

    Greg
    There really is no upgrade path for the 1" drivers that does not involve replacing the horn, which usually means something that won't fit in the cabinet, which is why I just went ahead and built from scratch.

    4430's are what they are, which is very good. For me, I tried adding a tweeter to get them to sound more like a big 4-way monitor, but it just wouldn't jell with a 2405, I'd like to try with a 2404, but just the physical placement causes problems. The magic goes away. Part, if not most, of the magic is the wide beamwidth that does not fall of until the UHF level drops.

    In the end, I just swapped in Radian aluminum diaphragms and live with the rolled off UHF. I do like the aluminum sound better that the Ti, which can really get irritating if you try to get them the do UHF by playing with the L-pad/Pot. I figured, having some rolloff sounded better, and the aluminum can actually get a bit more top end without the tizzyness taking over...
    Mike Scott in SJ, CA
    Drive 'em to the Xmax!

  6. #21
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    Mike -- A ton of help!

    I printed your post out and placed it with some other information from the LH site. I'm beginning to get a grip on the charge-coupled concept.

    I think my first try will be to upgrade the crossover caps, place the 4430s upside-down on the cabinets, and then bi-amp them. My preamp will allow me to adjust crossover points for each signal. I'll look for a sweet spot -- using your observations about the limitations inherent in the system components. And go from there.

    Thank you again, Mike.

    Greg

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