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Thread: JBL 4344 Clones

  1. #61
    Senior Member christo's Avatar
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    Quote Originally Posted by fencki View Post
    thx for your answer.
    you helped a lot!

    i have one more question for my JBL 4345 clones.
    beacause i have no 2122h i got one 2123h.
    can i use this crossover from 4344 MK2 with chassis 2123h and build up the 3145 crossover?:

    http://www.audioheritage.org/vbullet...l=1#post397270
    (#53)


    please help with that too...
    so i can start to order the parts for the crossover.

    big thx!!!



    btw you did a REALLY GREAT job with ur JBLs. just phantastic!

    My understanding is that the 4344 MKII crossover will get you the smoothest sound out of the 2123 for this type of application. The issue would be the crossover point of the 2245 would have to be raised to 340Hz from 290Hz as in the stock 4345 with a 2122.

    Most people in the forum dont like having the 2245 play this high.

    There is a lot of information on the differences between the JBL vintage 10 speakers here,

    http://www.audioheritage.org/vbullet...2121-2122-2123

    as they are not considered to be that interchangeable.

    There much discussion on the 4344 MKII crossover youll have to search the forum on your own as it is spread across multiple threads.

    Chris

  2. #62
    Senior Member ivica's Avatar
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    Quote Originally Posted by fencki View Post
    thx for your answer.
    you helped a lot!

    i have one more question for my JBL 4345 clones.
    beacause i have no 2122h i got one 2123h.
    can i use this crossover from 4344 MK2 with chassis 2123h and build up the 3145 crossover?:

    http://www.audioheritage.org/vbullet...l=1#post397270
    (#53)


    please help with that too...
    so i can start to order the parts for the crossover.

    big thx!!!



    btw you did a REALLY GREAT job with ur JBLs. just phantastic!
    Hi fencki,
    As I can understand there is an error in the drawing presented on the #53
    C1, C3, C5 and C7 form equivalent C=36/2=18uF, but from Giskard L=1.8mH, and C=14uF......
    as hi-pass network -6dB relative to the LF part is round 1.3kHz

    regards
    ivica
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  3. #63
    Senior Member christo's Avatar
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    Quote Originally Posted by ivica View Post
    Hi fencki,
    As I can understand there is an error in the drawing presented on the #53
    C1, C3, C5 and C7 form equivalent C=36/2=18uF, but from Giskard L=1.8mH, and C=14uF......
    as hi-pass network -6dB relative to the LF part is round 1.3kHz

    regards
    ivica
    Ivica

    I curious as to why you consider the schematic wrong as the section you are referring to comes from the JBL stock 4344 MkII schematic which has the C5, C7 as 72uF which in a CC network would be 2 x 36uF. Or am I missing something?

    I was not aware that Giskard had done a schematic for a 2245/2123 crossover if he did could you point me to it I would be very interested in looking at it.

    Chris

  4. #64
    Senior Member Ian Mackenzie's Avatar
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    http://www.audioheritage.org/vbullet...-Mk-II-network


    The capacitor values in the mid filter are for charge coupling

    The values are correct when simulating the voltage drive in LEAP.

    The measured acoustic response in LMS is correct for the 4344mk11 schematic

    The use of the 2245 requires an active 3rd order filter

    Some users have reported using an active 4th order filter

  5. #65
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    Quote Originally Posted by Ian Mackenzie View Post
    http://www.audioheritage.org/vbullet...-Mk-II-network


    The capacitor values in the mid filter are for charge coupling

    The values are correct when simulating the voltage drive in LEAP.

    The measured acoustic response in LMS is correct for the 4344mk11 schematic

    The use of the 2245 requires an active 3rd order filter

    Some users have reported using an active 4th order filter

    hi.
    can you please explain that, for somebody not that good in crossovers?
    are the corrected values right, what ivica suggested? or the original ones former posted?
    how should the crossovers for the 2245h and 2123h look like if using the 2123h and the crossover for 4344 mk2?
    i mean the crossover frequencies are different (290HZ in 4345 and 340HZ in 4344)

    using a 3rd or 4th order filter?
    can u show a schematic for the usage of 2245h and 2123h?

    i dont have such simulating programs so i have to ask the pros here...


    thanks a lot and greetings from vienna
    slavko

  6. #66
    Senior Member Ian Mackenzie's Avatar
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    http://www.audioheritage.org/vbullet...l=1#post390896

    This post read please.f
    Ft
    Original values are correct

    TWhen you go off the reservation and mix different schematic for mid and HF we cannot guarantee the outcome but the filter values for the 2123 are correct in the 4344mk11 schematic.

    The 2122 and 2123 are slightly different drivers.

    As l recall the 2123 is slightly f sensitive and tthe low end response is different.

    The 2122 was specifically designed for the 4345 monitor.

    Unfortunately l am not in a position to provide details of the 2245 filter right now.

    NFilters follow a mathematical transferfunction denoted by filter poles usually 1-4 poles in analogue filters.

    1 pole is a 6 db slope...usually a very gentle slope but no good for the 2245.

    3 pole is a 18 db filter and is better for the 2245.

    4 pole is 24 db and is steeper slope and can be used for the 2245.
    Do a search of the 4345 monitor.

    The concept of bi amping is simple enough.

    DO NOT use a passive crossover for the 2245.

    I suggest acquiring a adjustable active filter like the Ashley and adjust the level until it seems subjectivity correct.

    Anywhere from 250-340 Hz is going to work.
    Last edited by Ian Mackenzie; 11-11-2016 at 02:26 PM. Reason: FtFf

  7. #67
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    Quote Originally Posted by Ian Mackenzie View Post
    http://www.audioheritage.org/vbullet...l=1#post390896

    This post read please.f
    Ft
    Original values are correct

    TWhen you go off the reservation and mix different schematic for mid and HF we cannot guarantee the outcome but the filter values for the 2123 are correct in the 4344mk11 schematic.

    The 2122 and 2123 are slightly different drivers.

    As l recall the 2123 is slightly f sensitive and tthe low end response is different.

    The 2122 was specifically designed for the 4345 monitor.

    Unfortunately l am not in a position to provide details of the 2245 filter right now.

    NFilters follow a mathematical transferfunction denoted by filter poles usually 1-4 poles in analogue filters.

    1 pole is a 6 db slope...usually a very gentle slope but no good for the 2245.

    3 pole is a 18 db filter and is better for the 2245.

    4 pole is 24 db and is steeper slope and can be used for the 2245.
    Do a search of the 4345 monitor.

    The concept of bi amping is simple enough.

    DO NOT use a passive crossover for the 2245.

    I suggest acquiring a adjustable active filter like the Ashley and adjust the level until it seems subjectivity correct.

    Anywhere from 250-340 Hz is going to work.

    ok. thanks for your reply.
    i will do more research and think about all the stuff. my head is full of infos. mixing all up...
    thx

    actually i am thinking about an mini-dsp 4x10 HD... or 2x4 HD...
    maybe fully active. but 8 amlifiers will be a real overkill!


    br
    slavko

  8. #68
    Senior Member Ian Mackenzie's Avatar
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    That's it

    Do some reading to get a general idea

    The lovely people over in the USA are a little pre occupied right now so apologies if they are not around

  9. #69
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    Quote Originally Posted by Ian Mackenzie View Post
    That's it

    Do some reading to get a general idea

    The lovely people over in the USA are a little pre occupied right now so apologies if they are not around
    i really can imagine! i was really (lets say) supriesed about the election and the final result...

  10. #70
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    did you ever try out the mini-dsp?

  11. #71
    Senior Member Ian Mackenzie's Avatar
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    No only analog at this point

    You would need to emulate the voltage drives in the mini dsp which are optimised for the specific drivers and baffle placement in the Xy axis domain.

    The key advantage of dsp is phase alignment of the mid and horn crossover point but this is only for one point in space.

    I there recommend you bi amp the woofer and mid start with and use the dap to EQ the woofer response below 150 hertz where room placement impacts on the subjective outcome.

  12. #72
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    Based upon my experience using the 2123 with the 4344 MKII crossover it does, in fact, work quite well when used within a hybrid 4344/4345 set up. I've done this myself and I have heard Christo's set up. No, it might not meet the ultimate technical analysis parameters, but to my ears, based upon my own 4345 experience and having A-B'd my own 2123 franken version....it simply works quite well.


    No, the 2123 doesn't sound like a 2122, but both are really great drivers in this context and I am hard pressed to pick a favourite.

  13. #73
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    hi
    thanks for your input here...

    br
    slavko

  14. #74
    Senior Member Ian Mackenzie's Avatar
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    For those interested l have recently implemented the 4344mk11 full passive crossover using the 2245.

    I used
    2245H
    2123H
    2420 with aquaplas dusted diaphragm
    2405

    There has been much discussion on the best approach to using the 2123H with the equivalent Giskard filters.

    I propose to measure the hyprid MK11 (2123H filter) with the Giskard HF and UHF filter and compare to the complete 4344mk11 filters.

    I have not compared the filters subjectively.

    But l must say the complete 4344mk11 crossover using the dusted diaphragm is spectacular.

    Gone is the live razers edge voicing of the 4343.

    The transition of the 2123H to the horn is seamless and natural while the 2405 compliments the top end with crystal like clarity.

    I plan to post further analysis of the above soon including biamping

  15. #75
    Senior Member Ian Mackenzie's Avatar
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    The pic below is the amplitude response comparing the Giskard hyprid (mk11 mid filter for the 2123H) and the Giskard horn and slot filters

    The violet curve is the Giskard hyprid filter, green is the MK11 filter .

    The Lpads were at maximum position and the test mic was located in the near field on axis with the bottom of the horn lens.

    Given this measurement was indoors and ungated the response within 5 db from 40 Hz to 15khz is remarkable and a testament to the subjective performance .

    Despite attempts to adjust the horn and slot Lpad l was unable to achieve an acceptable result compared to the MK11 filter per attachment.

    If anyone is considering the 4344 as a diy project, given the 2122H mid is NLA the 2123H is a stellar midrange driver with the MK11 network. I have owned the 2212H using the Giskard equivalent network and would describe the MK11 based 2123H as a comparable system.

    The MK11 network was constructed with Hovland capacitors only because they are readily available.

    The charge-coupled Solen fast cap is a well known option. I am completely agnostic about the subjective attributes of capacitors and let the quality of implementation do the talking.

    Subjectively l would describe the hyprid as hideously coarse sounding with a veiled presentation.

    The response is an indicator of overall smoothness but manner in which carefully chosen slopes compliment the individual characteristics of the drivers is outstanding.

    The 2123H in the MK11 crossover with dusted diaphragms and 2405 is the smoothest and best voiced 4 way JBL l have heard to date and is up there with the 4338 and other JBL Blue baffle monitors.

    Cutting and pasting schematics is a risky as the above test indicates.

    (Do not confuse with the other Giskard filter that works for the 2123/2202 drivers )

    You may be wondering if the MK11 works for the 2235 and the 2245 drivers.

    I have not tried the 2235H yet but the 2245 seems to work very well in full passive mode.

    I will post details of the 2245 passive and active networks soon.

    For those who are interested l can provide fabrication of the MK11 network, testing with LMS/LEAP 5.
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