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Thread: 2123H vs 2122H in a 4343 monitor

  1. #1
    RE: Member when? subwoof's Avatar
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    2123H vs 2122H in a 4343 monitor

    Anyone have the experience of using the 2123 instead of the 2122 in the 4343 monitors?? Aside from the obvious efficiency difference any suggested changes to the network? sub...:0)

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    Re: 2123H vs 2122H in a 4343 monitor

    Originally posted by subwoof
    Anyone have the experience of using the 2123 instead of the 2122 in the 4343 monitors?? Aside from the obvious efficiency difference any suggested changes to the network? sub...:0)
    Rather than go on yet another rant

    Look at the 4344 Mk II schematic to see how JBL delt with the rising response of the 2123 in a 4343/4344/4345-type system

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    Re: 2123H vs 2122H in a 4343 monitor

    4344 MK II
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    Senior Member Guido's Avatar
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    Giskard,

    please give some advice to the schematic. It's a charge coupled and I'm not into this as many other maybe.

    What is the important difference between both networks (4343, 4344)?

    Where do you have the info of rising response of 2123? In the spec sheet JBL show a toooooo flat response.

    Do you have a own spec sheet? Please post.

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    "Where do you have the info of rising response of 2123?"

    In my head. My ears have stopped ringing

    Here are the voltage drives of the MF passbands in the 4343 and 4344 Mk II. The 4343 uses the 2121, the 4344 and 4345 use the 2122, the 4344 Mk II uses the 2123.
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    Senior Member Guido's Avatar
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    If this is the voltage drive then the response of the 2121 is falling with rising frequency?
    I'm confused. Thought it is rising

    Heeelp!

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    Originally posted by Guido
    If this is the voltage drive then the response of the 2121 is falling with rising frequency?
    I'm confused. Thought it is rising

    Heeelp!
    Don't confuse me Guido
    The 2121 has breakup issues due to it's soft inverted center dome. The 2123 has a rising response so the 4344 filter attenuates it faster.

    Anyway, just pop a 2123 into a 4343 and see how you like it. You might think it's just fine. Try a 2122 and see how you like that one too. Seriously, it's the only way to see which one you prefer.

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    Senior Member Guido's Avatar
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    We should sit together with a German Beer and discuss this personally.

    I went through this many times as you know that I am using a 2012H in my 4343. They have rising response from 800Hz and up. At 1200Hz its plus 6dB.

    You once posted a response curve of the 2122H. It have slightly the same problem between 800 and 1000Hz. Beyond 1000Hz it's solved. I never saw the curve of the 2121.
    So if my 4343 network rises the response than I have a peak in my 4343 response. I think I do hear that.
    What to do?

    And how do you calculate the voltage drive? What program is it?

    Thanks!

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    RE: Member when? subwoof's Avatar
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    OK - I'm impressed...

    Second question for the JBL TECHBOT: Do you have the part number for the ME150H recone kit? My JBL service center doesn't have it in his consumer listings ( I assume due to the overseas use only ) and unfortunately we cannot call carla at JBL anymore...

    I have a pair of 2226H frames they could drop in - this should be an improvement over the 2235H if I'm going to do all the other mods...

    Thanks in advance!

    PS to guido - Zwei Deutch bieren sounds good to me...

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    Hello subwoof

    Both the ME120 and ME150 are marked "Cone/Diaphragm Kit Not Available. Defective Speaker Should Be Replaced".

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    RE: Member when? subwoof's Avatar
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    Figures on the recone kit....they pull the "FSO" with the 1400Nd and mose of the Neodymium stuff too....Oh well....

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    Originally posted by Guido
    We should sit together with a German Beer and discuss this personally.

    I went through this many times as you know that I am using a 2012H in my 4343. They have rising response from 800Hz and up. At 1200Hz its plus 6dB.

    You once posted a response curve of the 2122H. It have slightly the same problem between 800 and 1000Hz. Beyond 1000Hz it's solved. I never saw the curve of the 2121.
    So if my 4343 network rises the response than I have a peak in my 4343 response. I think I do hear that.
    What to do?

    And how do you calculate the voltage drive? What program is it?

    Thanks!
    You might want to try a little notch filter around 900 Hz then. Search the web for parallel and series notch filters. You'll want to use a parallel notch filter which goes in series with the transducer.

    You can measure the voltage drive of a filter with a voltmeter and an oscillator. You can measure it using the actual transducer or with an 8 ohm or 16 ohm dummy load. Obviously you will get different results depending on which you use Using transducers is fine but you should also use a dummy load to get a proper "mapping" of the filter.

    Any spice software package should be able to allow you to model filters. I think pspice still has a free version or student version that should be adequate.

    Here is the standard test setup for running voltage drives on JBL networks:

    http://www.jblproservice.com/pdf/Net...%20Fixture.pdf

    ***

    Oh, and if you are going to get serious about modeling filters for different transducers then you will want to create the equivalent circuits for the transducers you are planning to use. Equivalent circuits can be determined from the TS parameters. For instance, here is an example of the equivalent circuit of a 2235H:
    Attached Images Attached Images  

  13. #13
    luxmanlover
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    Yikes

    If that's the kind of stuff I need to know in order to design passive filters in PSpice, I'd better stick to active ones.
    Kelly

  14. #14
    Senior Member Guido's Avatar
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    Originally posted by subwoof
    OK - I'm impressed...

    and unfortunately we cannot call carla at JBL anymore...

    PS to guido - Zwei Deutch bieren sounds good to me...
    Whos carla?

    Your German is good! Sounds like you have been on the oktoberfest once

  15. #15
    Senior Member Guido's Avatar
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    Thanks Giskard!

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