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Thread: JBL 4346 DYI with 2123H

  1. #76
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    testing testing 123

    Ian,

    i tried to do it as explained but my fear is that my 2123's are busted. at the same volume the same distance i have about 3 to 4 db difference between the right and the left speaker. Next if i'm trying to bring down the horn and the slot to the same spl as the one of the mid after the 3.5 db reduction i will have to go way down on the l-pads which translates into a very damped sound. So there is a clear imbalance between the mid speaker and the rest of the drivers.

    I believe i should change the 2123 firat and repeat the test.

  2. #77
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    Okay,

    That's a bitch.

    Are you sure the amp balance for L+R is the same?

    You could swap the input of the amp to check this.

    Can you bypass the crossover and test each 2123 individually with the direct signal from the amp with the SPL meter.

    This will prove if it's one of the drivers or a malfunction of one of the crossovers.

    If the later we will need to measure the voltage drives of the mid filter and compare to each other.

    We can investigate the horn filter following this step.

    PS. If it's any comfort it's unlikely one of the drivers would have different sensitivity unless one was 8 ohms while the other was 16 ohms.

    They are either working or blown.

  3. #78
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    disaster

    left is 8 ohm right is 6.9 ohm measured at the posts.
    difference in spl left is a full 5 db lower than right. The drivers were fed directly from my accuphase. no balance issue on the amp. I made the test with 800 hz sine wave.

    I think i need to buy other speakers.

  4. #79
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    the left speaker is a mess

    the membrane is ripped under the cap and was glued to the spider in the worse manner possible And with a ton of glue. 😡

    No chance... need new speaker.

  5. #80
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    Okay,

    "Also i realized that the left mid speaker was badly repaired and has a ton of glue at the neck of the membrane where it meets the spider on the outside. I am afraid to look below the cap. Thing is i will have to purchase another 2123 dont know if it worth reconing with aftermarket recone kit."

    So it was the left reconed speaker that is faulty.

    That is the voice coil resistance?

    Have you compared how it sounds to the left speaker?

    Suggest you do a full response measurement and compare both drivers to confirm the overall sensitivity is lower (not just one frequency).

  6. #81
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    Quote Originally Posted by Ian Mackenzie View Post
    Suggest you do a full response measurement and compare both drivers to confirm the overall sensitivity is lower (not just one frequency).
    Uh, er, it might be a good idea to go back to Square One and determine the status of each element. Working hard on "perfecting" output is moot if the last elements in the signal path are questionable...
    bo

    "Indeed, not!!"

  7. #82
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    Quote Originally Posted by boputnam View Post
    Uh, er, it might be a good idea to go back to Square One and determine the status of each element. Working hard on "perfecting" output is moot if the last elements in the signal path are questionable...

    Yes agreed, l meant the driver only (sweep)

    We are trying to determine if they are H or J ?

  8. #83
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    The weather is unsuitable for ground plane measurements outside so l have set up testing of the network (per hyprid cover) in my HT room.

    I have obtained some parts and wound inductors with the LCR meter for the Giskard HF and UHF.

    The plan is to see what the 4344 response should look like with the hyprid network and sort out the L pad levels.

    I also want to validate the iPhone measurements against LMS.

    If the phone is good we will try and come up with a best practise that can be adopted by other iPhone users.

  9. #84
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    Attached is the 4344mk111 (full crossover) will all L pads up full.

    Green is near field, Pink is gated 2 metres.(LMS)

    The lower end is the room effects.

    Overall this is as expected for this type of system.

    Once l have set up the Giskard filters I will measure and compare with the iPhone
    Attached Images Attached Images  

  10. #85
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    Great work Ian,

    Now we know how it should look like. looking forward to seeing the giskard graph.

    how will you combine the two parts of the filter.

    I am currently ordering the H version of 2123s from japan. one year guarantee.

    I know that finally our struggle will pay off. Already the sound in my room has improved alot and I cannnot waot to see the final result of our efforts.

  11. #86
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    I will simply connect it like the other filter but disconnect the 4344mk11 filter in its place.

  12. #87
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    Dayton mic

    My Dayton mic has arrived. Now I can do some serious measurements. Awaiting instructions....

  13. #88
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    internal wiring recommendation

    Any recommendation on the internal wiring of the speakers?

    what should I use? solid core copper or stranded copper? what caliber?

  14. #89
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    latest measurements. pink noise full on lpads one meter on axis with the horn with the lenses on. calibrated dayton micName:  image.jpg
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  15. #90
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    That looks much better

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