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Thread: 4343 VS 4345 network?

  1. #1
    tv506
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    4343 VS 4345 network?

    Hi, I am planing to build a pair of 4343 speaker but I have hard time finding the 10" mid range and the network. beside the 2121, I don't know what other 10" midrange can be replace? I realy like the sound of the 2121. Also, I can not find 4343 network but I found set of 4345 network availble. Are the 4343 and 4345 network the same? If anyone have the diagram available, please send me a diagram of both so I can compare.

    Thank you,

  2. #2
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    Re: 4343 VS 4345 network?

    4343 Schematic

    4345 Schematic

    The 3144 and 3145 networks are the same.
    The 4345 originally used the 2421B compression driver. Later production runs used the 2425J compression driver.
    I have several brand new 2122H transducers for sale.
    Send me a PM if interested.
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    Last edited by 4313B; 10-02-2003 at 09:28 AM.

  3. #3
    Tom Loizeaux
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    Search eBay for JBL 2405s, and you'll find a pair of 4343s that are supplying the 2405s. This gentleman, Dave, may still have a pair of 2121s and a pair of crossovers from his 4343s. Contact him right away.

    From my reading of posts here on the Forum, I seem to feel that the 2121s may be the best 10" low-mid drivers for the 4343 type speakers!

    Good luck,

    Tom

  4. #4
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    The 2121 does have breakup issues due to it's soft inverted paper dome. The 2122 is the "better" driver. The 4344/4345 network is also the "better" network, so if one is starting from scratch...

    On the other hand, plenty of people never notice any problem with the 2121 and the 4343 network is easier to build.

  5. #5
    Member Bill Shenefelt's Avatar
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    JBL 4 way system

    I have a home built cabinet system. It started with the drivers and the crossovers(design and parts from JBL) for the L300's. A 15 inch 136A bass, an LE85 horn driver and a slot radiator. Since then I added the 10 inch midbass driver and changed the horns on the LE 85 compression drivers from the 800 cps to the 1200 cps horns. I have JBL design and parts incorporated for the passive 10 inch cone to horn and horn to slot radiator but have been trying to find the right active crossover point and slope for the 136A to the 10 inch midrange. I had thought that an active crossover would be superior to the passive. Initially the addition of the midrange was nice for midrange "non horny" sound but I seem to have lost the great punch from the system that was present with the straight active 800 cps crossover without the midbass cone. Any suggestions?

  6. #6
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    Clarifying your statement would be a good first step.

    Quote Originally Posted by BillS.
    I have a home built cabinet system. It started with the drivers and the crossovers(design and parts from JBL) for the L300's. A 15 inch 136A bass, an LE85 horn driver and a slot radiator.
    - Do I understand the following correctly ?;
    (i) At one time you built a DIY L300 that used a passive crossover which was built according to JBLs' network schematics. The horn used was a 2312 ( HL92 ). Is that all correct ?
    (ii) Then you biamped this setup , according to the proper JBL technique ( ie ; leaving select passive components in place ). Is that correct ?

    Quote Originally Posted by BillS.
    Since then I added the 10 inch midbass driver and changed the horns on the LE 85 compression drivers from the 800 cps to the 1200 cps horns.
    (i) Which 10" midbass are you using ?
    (ii) What are the model numbers of the horns that you swapped in ?


    Quote Originally Posted by BillS.
    I have JBL design and parts incorporated for the passive 10 inch cone to horn and horn to slot radiator,,,,,
    (i) I'll assume that you have rebuilt your original 3-way passive crossovers ( modeled on the N333 ) and have built in their place a N3143. Is this correct ?



    Quote Originally Posted by BillS.
    ,,,,,,but have been trying to find the right active crossover point and slope for the 136A to the 10 inch midrange.
    - I think the crossover point is in the 290hz region .
    - Whatever it is exactly, the answer is well documented within this forums' archives. ( You'll want to mount a search . )


    Quote Originally Posted by BillS.
    I had thought that an active crossover would be superior to the passive. Initially the addition of the midrange was nice for midrange "non horny" sound but I seem to have lost the great punch from the system that was present with the straight active 800 cps crossover without the midbass cone.
    (i) Did you duplicate JBLs' network designs ?


    Quote Originally Posted by BillS.
    Any suggestions?
    - They'll be dependant on the answers to the above questions .

    ( Your observations are more likely the result of choices & decisions that you made when you migrated your 3-way network to a 4-way network. )



  7. #7
    Member Bill Shenefelt's Avatar
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    I built a 4343 using the 136A bass, 1 inch horn driver and slot radiator from my L300 home project. I changed the horn to the JBL 1200 cps horn for the 4343 instead of the hl92 (which was shorter and designed for an 1200 cps, not like the 800 cps in the L300) I used the initial 6 cubic foot enclosure for only the 15 inch bass and added an upper sealed cabinet (to their volume spec) to house the 10 inch 4343 midbass. I mounted the horn and slot radiator in a panel above that second enclosure. This would allow me to reposition the 10 inch to 15 inch coils if need be for better phase characteristics. The horn and slot radiator are however fixed to the same plane as in the 4343. That is surface mount to a single plane. I used JBL provided passive components and their network schematic for the upper crossovers (1200 cps for midbass to horn and 9k f (i think it was) for the horn to slot radiator. Whatever they used -I bought the components from them and assembled to their schematic) I still needed a crossover to biamp the system. 15 inch on one amp and upper drivers on the second amp. I just bought a marchand active corossover (3 way as a safety precaution in case I want to triamp. I ordered 24dB/octave at 300 and a backup at 400 cps for this biamp setup. I can alter the crossover point and slope(order) independantly for high and low pass unit using this crossover with different cards. I am looking for advice as to what slopes and crossover points might best suit this system for best overall sound, not necessarily high power handling.


    Quote Originally Posted by Earl K View Post
    Clarifying your statement would be a good first step.



    - Do I understand the following correctly ?;
    (i) At one time you built a DIY L300 that used a passive crossover which was built according to JBLs' network schematics. The horn used was a 2312 ( HL92 ). Is that all correct ? YES
    (ii) Then you biamped this setup , according to the proper JBL technique ( ie ; leaving select passive components in place ). Is that correct ?

    No I converted to 4 way trying to duplicate the 4343 using JBL provided parts and schematics except fot the biamp part

    (i) Which 10" midbass are you using ? The one they put in the 4343 with the inverted dustcap
    (ii) What are the model numbers of the horns that you swapped in ?

    Don't remember. They were the 1200 cps ones JBL used in the 4343


    (i) I'll assume that you have rebuilt your original 3-way passive crossovers ( modeled on the N333 ) and have built in their place a N3143. Is this correct ?


    If JBL used that in the 4343 I have that


    - I think the crossover point is in the 290hz region .
    - Whatever it is exactly, the answer is well documented within this forums' archives. ( You'll want to mount a search . )

    HOW do I do such a search? I do know they used 12dB/octave at 300 I think but was not sure if it was to allow for higher power handling or better transient responce.


    (i) Did you duplicate JBLs' network designs ?

    YES


    - They'll be dependant on the answers to the above questions .

    ( Your observations are more likely the result of choices & decisions that you made when you migrated your 3-way network to a 4-way network. )



  8. #8
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    I use 24dB/octave active at 290Hz between my 2245H (18") and 2122H (10"). This is the recommended frequency (but not the slope, JBL recommend 12 dB/octave) for my 4345's and I believe, also for the 4343. It works fine according to my ears and my RTA.

  9. #9
    Member Bill Shenefelt's Avatar
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    [quote=Earl K;156494]Clarifying your statement would be a good first
    (ii) What are the model numbers of the horns that you swapped in ?

    Horns are marked 2307

    With the new crossover I will also have the option of a triamp with a second active corssover at the 1200 cps and using a McIntosh 35 w/ch tube amp for the horns if that is better yet.

  10. #10
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    Hi Bill,

    - Here are the two schematics for the networks that I previously mentioned .

    - It would be constructive to compare your 4-way networks to this N3143 network & then report back any deviations which might have been made.
    ( There's a possibility that JBL had you build a different network . )

    - BTW; Just about every major JBL network that I'm aware of has some form of builtin EQ for the specified components. So , changing either ( or both ) the component or network will result in less than satisfactory results .
    - The short horn 2307 needs the built in EQ boost that the network provides ( 3 pole bump filter found in the hipass portion ) .

    - When biamping or triamping / one wants to leave in place these EQ elements . This translates into biamping ( or triamping ) according to JBLs' directions .

    Quote Originally Posted by Bill
    Any suggestions?
    - The easiest ( & most common ) mistake to make / is that of getting the different drivers' polarities wired up wrong. ( You'll notice that the older network schematics aren't exactly clarion in their polarity directions. )
    - Check to make sure the 15" woofer is wired so that it's in reverse polarity to the 10" midrange ( assuming you're using 12 db per octave slopes ). Specifically, a mistake made here will result in a significant response hole / which would help explain your initial posted observations .
    - If you end up using a 24 db / octave crossover for this @ 300 hz point, then wire the woofer & 10" midbass with the same polarity ( ie; same phase ).
    - ( The 10" mid & le85 horn & 2405 slot are typically wired, all having the same polarity )


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    Hi Bill

    BTW; nice woodgrain from what I can see .

    - Looking at the above image ( which you posted ) suggests that the midbass blending in your setup is suffering from a combination of destructive effects .


    - When using the 3143 network, keep in mind that the networks' slopes & the Xover points are partially dictated by the physical layout of the components . The maintenance of original driver spacing is necessary so that the network can create the proper blend between the drivers .

    So when making a substitute 4343 ;
    (i) The distance from center of woofer to center of mid-driver should be the same as the original system .

    (ii) The N3143 was designed to filter a 2121 that is set into a large baffle. The smaller baffle ( in your case ) brings with it less LF loading ( so a bit less output in the lower range ). You might try reducing your hipass slope on the 2121 from 12 db to 6 db to see if this recaptures any lost energy in this area.

    Observation ; Somewhere in the archives is a complete set of construction drawings for a 4344. These were drawn up by a europeon member of LHF.
    - Offhand I didn't save the link ( hopefully maybe someone else has it on hand & can post it ).
    - With those drawings in hand you can get a good guide for the necessary working distances ( between driver centers ).


  12. #12
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    EarlK is right. When you make adjustments to driver array- the network's performance will stray. It was not designed to accomodate both the change in layout and the change in voicecoil alignment (although I do like your layout!). Using that set up- you may get good results. You may even get great results. But I doubt you will ever get truly excellent results until you take more extreme measures to compensate for any and all errors.

    It looks like you have some nice drivers to play around with. You've already invested in custom cabinets. My suggestion? Step it up. I think a DEQX (or DBX Driverack for less money) might be in order to reach the next level of performance. Try an active 2way crossover with room correction, or even use it as a 3way unit (...keep the passive section of the mid to horn- eliminate the other legs of the network. Treat that passive section like a single driver bandpass. This will be a triamplified, 4way speaker rig).

    Besides being amazing digital crossovers, all other variables can be corrected for you such as time alignment, phase correction, excellent parametric EQ, room correction, a 24/96 DAC, and even an RTA with pink noise generation. The DEQX has the added benefit of being your pre with many features on the hand held remote control. All of these things are done with state of the art accuracy. You can mess around with passive compensation your whole life and not reach the performance of these units right out of the box. The DEQX is pricey (worth it) at $2.5K USD used. The DBX unit can be purchased new for about $400 USD.



    Cheers,
    Nate.

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    This is almost the same thing I am doing but my lo-mid is in a horn cabinet made by Hill. I am using 3 QSC amps and a Rane ac23 crossover but I need a passive for the 2405

  14. #14
    Heather [Senorita member] hjames's Avatar
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    And I'm doing mine by hybriding an L200 for the Low and HF, while the MidBass and VHF (slot) are in an external case similar to the "doghouse" of the 4343/45. Currently working through issues with biamping via a JBL M552 active crossover.

    But I have some driver replacements yet to go ...
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  15. #15
    Member Bill Shenefelt's Avatar
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    New caps and resistors for 4343

    [Earl K replied:

    - Looking at the above image ( which you posted ) suggests that the midbass blending in your setup is suffering from a combination of destructive effects . ]

    It will be an easy task to get the 10 inch 2121 center to within a quarter inch of the center to center to the 136A. All I have to do is flip the bottom enclosure. This will however place the port close to the floor. I can make a bigger baffle for the upper three drivers also.
    I will be using a 24/0octave at 300 cps Marchand
    XM44 and can also go to the 12k crossover with active components in the XM44. I had been considering doing a crossover at 1200 cps between the 10 inch and HF drovers but now it seems tha it should be put at the horn to slot radiator point.
    I do want to update the caps and resistors, keeping the JBL provided inductors.
    All resistors would be 1% Mills 12 w non inductive, parallelled for power handling where necessary.
    I would be replacing the 20uF, the 13.5, the 4 , the 1.5 and the 1.0uF caps. (I have no 52 or 72 as that point is biamped). I do not know what the origonal JBL crossover is using. The three largest values are paper wrap and look like wax filled ends. What type are they?
    I can go Dayton 1% metallized polypropylene,
    Sonicap polypropylene, or
    Claritycap polypropylene. I found a post in another thread referencing a guy in the Netherlands who tried and "reviewed different caps. As would be expected, most are not readily obtainable and some that were cost prohibitive. He did like the Clarity caps despite the "realtively low cost"
    I have been searching for a source of polystyrene jumpers but cannot find one. Anyone know of one?
    Anyone have a preference in the above 3 brands or feel a different brand is better for the horns and 10 inch? I have studied the threads on using a 9 v biased network but am a little leery of taking that step, especially with the inductor changes and the need to recone the 2121 drivers to convert to a 4345 setup.

    - When using the 3143 network, keep in mind that the networks' slopes & the Xover points are partially dictated by the physical layout of the components . The maintenance of original driver spacing is necessary so that the network can create the proper blend between the drivers .

    So when making a substitute 4343 ;
    (i) The distance from center of woofer to center of mid-driver should be the same as the original system .

    (ii) The N3143 was designed to filter a 2121 that is set into a large baffle. The smaller baffle ( in your case ) brings with it less LF loading ( so a bit less output in the lower range ). You might try reducing your hipass slope on the 2121 from 12 db to 6 db to see if this recaptures any lost energy in this area.

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