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Thread: Cross-over schematics for the 4660

  1. #1
    Senior Member Jan Daugaard's Avatar
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    Cross-over schematics for the 4660

    Does somebody have the schematics for the 4660 cross-over?

    I'm not sure what the difference between the 4660 and the 4660A is (it could be the woofer 2225 vs 2226), and I need the schematics for a 2226 woofer and a 2425/2426 compression driver on a 2346 horn.

    Thanks in advance!

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    Ok
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    Senior Member Jan Daugaard's Avatar
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    L3 switch

    Hi Giskard,

    thanks very much for the schematic -- 4660A_Page_1.jpg contains just what I was looking for.

    It appears that L3 has a switch with 5 positions. Do they represent 5 choices of induction between 0 mH and 3.3 mH?

    And what does NC stand for?

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    It's a tapped autotransformer. You'd have to measure the taps if they aren't specified in the schematic.

    No Connection.

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    RIP 2011 Zilch's Avatar
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    It's an odd note about the 2426 impedance. Looks like they switched to the 16-Ohm "J" in the "A" version, and advised swapping out diaphragms in the originals when required....

    Ooops!

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    Senior Member spkrman57's Avatar
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    I noticed the 8 and 16 ohm 2426 reference also...

    Seems like they would both work unless I am missing the boat on this one.

    Not like I haven't been wrong before!!!!

    Ron

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    Senior Member spkrman57's Avatar
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    Still curious...

    Will using a 8 ohm or 16 ohm 2426 make a noticable difference with the 4660 crossover schematic!

    If nothing nothing else, the HF horn output would be off a few db!

    Hoping someone will chime in here!

    Giskard would be able to answer this question, someone talk him out of retirement.

    Ron

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    Quote Originally Posted by spkrman57
    Will using a 8 ohm or 16 ohm 2426 make a noticable difference with the 4660 crossover schematic!
    'Seems to me the 16 ohm version would be about 3db down from the 8 ohm version, but I'm not sure that exactly applies in this case. 'Curious how they use the same crossover in both versions. I wonder if they went to the 16 ohm to better match the level between the two different LF speakers?

    John

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    RIP 2011 Zilch's Avatar
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    Someone needs to model the HF section of the crossover with actual impedances of the two versions of the driver. From previous experience, there's more than just attenuation involved, as the different impedances shift the filter operating points proportionately. There's a HF boost loop there, too.

    I'm not comfortable doing that with the tapped inductor in there; there's considerable discussion on modeling those in other threads here, which I don't understand.

    Another option, which I might try, is to measure the actual performance of both drivers with an RTA and/or CLIO. That's a beast of a task, though, disassembling one of those things to get at the driver and yank the crossover. I DO want to swap in some 2226's, tho, to free up the 2225's for conversion to 2235's.

    They're the final stage of the "Quick & Dirty" project. August, maybe....

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    Senior Member spkrman57's Avatar
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    My curiousity would be the crossover frequency also!

    Would it change much, or does the other attenuation/HF compensation circuit components keep the load to the crossover constant regardless which one would be used(8 or 16 ohm).

    Ron

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    RIP 2011 Zilch's Avatar
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    Proportionately, according to the ratio of impedances. In two-pole filters, it also messes with the filter Q substantially. Look at your crossover component selection charts in the Parts Express catatlog....

    This is why I termed the note "Odd," above. It's as if they made a mistake building units with 2425H drivers. It may also be that the original crossovers are actually different. The change is linked to a specific crossover model number.

    I can get impedances with WT2, but definitive response curves will have to be measured quasi-anechoically using CLIO. RTA will reveal gross differences only, due to inherent averaging.

    Both practically and academically, it'd be a worthwhile exercise. I'm just not there yet. Gotta BIG 4688 subwoofer I need to load to play with them first.

    If you've got the stuff, try it yourself. We'll compare notes....

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    Senior Member Lancer's Avatar
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    I would have to measure the #4 tap on the 3.33 mH inductor and I don't feel like dragging it out and measuring it right now. Maybe later.

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    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Lancer
    I would have to measure the #4 tap on the 3.33 mH inductor and I don't feel like dragging it out and measuring it right now. Maybe later.
    You want me to generate impedance curves on WT2? Or do you know the impedances well enough already?

    I have two each 2425H's (if that's what's in 'em) and J's here, plus a pair each of 2426J and 2427H I could mount on one of those horns.

    [Gonna be a bear bustin' those painted-on horns loose. Gotta do it eventually, tho....]

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    Senior Member spkrman57's Avatar
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    Question on WT2???

    I bought mine and it came without cd to load into my pc.

    3 days later the cd rom arrived, I could not wait to see how she runs.

    Bummer!!! The damn unit never clicked in and did not perform any functions, just ran and ran without getting anywhere. The figures just kept changing but it kept telling me connection failure or internal fault.

    I have to send back to PE and wait for new unit to come back. I liked the old one even if it was antiquated, just thought the new one would be so cool.

    Sorry to hijack this thread, just wanted to know how your(Zilch) WT2 is working for you.

    Ron

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    Senior Member Lancer's Avatar
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    Bummer!!! The damn unit never clicked in and did not perform any functions, just ran and ran without getting anywhere. The figures just kept changing but it kept telling me connection failure or internal fault.

    I had the same problem. It turned out to be a USB issue. I can't remember if I hit my computer with a rubber mallet or simply pushed it off the table onto the concrete floor to get it to work. Maybe I just unplugged all the USB crap, turned the machine off, then back on and plugged the USB garbage back in. It works now.

    You want me to generate impedance curves on WT2? Or do you know the impedances well enough already?

    I was just going to dig up the inductor, measure the tap points and then model it with the standard JBL text fixture, 8 ohm and 16 ohm loads. I thought I had one sitting behind me but it turned out to be the 1.55 mH from the LX80, N333, 3133 and LX300. The other tapped autotransformers are downstairs in a box somewhere. If you want to post the impedance files for me to look at later that's fine.

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