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Thread: 2245H reconed as 2240H what is the result

  1. #1
    Senior Member mbottz's Avatar
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    2245H reconed as 2240H what is the result

    I am looking at a speaker which has the 2245H reconed as a 2240H. What is the effect of such a transplant? Is it good or bad? Anyone know the answer?

    Thanks

    MB
    Restoring the legend, one cabinet at a time

  2. #2
    Senior Member spkrman57's Avatar
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    I'm fairly sure that 2245 and 2240 are same cores.

    I have 2245 cores that have been reconed as 2240's arriving next week and will let you know how the results are when I have a chance to play them awhile.

    Ron
    JBL Pro for home use!

  3. #3
    Senior Member Guido's Avatar
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    A 2245H reconed as 2240H is a 2240H.
    Ok, except the foilcal.

  4. #4
    Senior Member mbottz's Avatar
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    As a subwoofer is the 2245 superior? Is it something that if played side by side in the same type enclosure I could hear a significant difference? What does it do to the value of a B460?

    Thanks

    MB
    Restoring the legend, one cabinet at a time

  5. #5
    Senior Member grumpy's Avatar
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    As a subwoofer is the 2245 superior?
    For home use? I'd say yes.

    ...hear a significant difference?
    or feel, ... most likely.

    What does it do to the value of a B460?
    Current price of a 2245H recone

  6. #6
    Senior Member spkrman57's Avatar
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    Specs on my 2245 recone to 2240H

    These are freshly reconed and have not been broke in yet:

    I listed the serial nrs that were used for the 2245 since I wanted to keep both identifiable.


    JBL 2240H #24026 2240H #24010
    Fs 31.68hz ---31.2hz
    Qes .32 ---.31
    Qms 7.2--- 6.8
    Qts .31 ---.3
    Le .87mH--- .87mH


    It will take me a few weeks and break them in before they each get their own 8 cubic ft ported cabs for LF duty between 40hz and 200hz.

    My room is so small that I don't worry about loading down below 35hz. The living room will not energize with those low notes, but the garage, kitchen and outside will!!!

    Ron
    JBL Pro for home use!

  7. #7
    Senior Member spkrman57's Avatar
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    Need opinion on 2240H specs of my drivers

    I see the Qms values I measured with WT2 are higher than the JBL 2240H specs.

    Does anyone have ideas on what caused that figure to be off???

    Could it be from the voice coil not being in the exact location in the gap???

    Or will it decrease upon break-in???

    Thanks for all comments/opinions!!!

    Ron
    JBL Pro for home use!

  8. #8
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    I guess it’s the foam surround that you find discouraging and ribbon cloth surround reinsures you with easy of mind and conference.

  9. #9
    Senior Member pos's Avatar
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    Here is a simulation of a 2245H (green) and a 2240H (red) in the B460 (8ft 26Hz)

    group delays are also higher for the 2240H
    Attached Images Attached Images  

  10. #10
    Senior Member grumpy's Avatar
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    Hi Ron,

    Change in compliance (Cms) will affect Fs (more compliance, lower Fs).
    Change in Fs will affect Qms in direct proportion.

    So... I'd expect a break-in to increase compliance, lower Fs, ... and therefore Qms.

    http://en.wikipedia.org/wiki/Thiele/Small

    As to what's 'normal' for a newly reconed 2240, perhaps you already have the
    best information.

    -grumpy

  11. #11
    Senior Member spkrman57's Avatar
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    Thanks grumpy!

    That is the info I was hoping for.

    I have to wait until I get some cabinets fixed up for them(3.8 cu ft tuned to 48hz result of F3 of 61hz per JBL sheet I found).

    I plan to use them with 2235 subs to fill in the bottom end.

    Regards, Ron


    Quote Originally Posted by grumpy View Post
    Hi Ron,

    Change in compliance (Cms) will affect Fs (more compliance, lower Fs).
    Change in Fs will affect Qms in direct proportion.

    So... I'd expect a break-in to increase compliance, lower Fs, ... and therefore Qms.

    http://en.wikipedia.org/wiki/Thiele/Small

    As to what's 'normal' for a newly reconed 2240, perhaps you already have the
    best information.

    -grumpy
    JBL Pro for home use!

  12. #12
    Senior Member grumpy's Avatar
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    That'll be an interesting setup. I hope the 2235's can keep up

    I'd be curious to see how/if the 2240's actually do drop Fs after some use,
    ...if you have time (and feel like bothering) to remeasure later.

  13. #13
    Senior Member spkrman57's Avatar
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    Have to wait to break in the reconed drivers....

    grumpy,

    I will be running the JBL 18" as a 2-way with compression driver and horn on top driven by either a single ended (triode-strapped EL34 monoblocks - 6 watt output) or a McIntosh MC-240 tubed amp. The 2235's will get a much larger SS amp to fill in the bottom.

    My listening room is very small, so not much wattage required.

    I will post results after burn-in when time permits.

    Thanks, Ron



    Quote Originally Posted by grumpy View Post
    That'll be an interesting setup. I hope the 2235's can keep up

    I'd be curious to see how/if the 2240's actually do drop Fs after some use,
    ...if you have time (and feel like bothering) to remeasure later.
    JBL Pro for home use!

  14. #14
    Senior Member spkrman57's Avatar
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    Awaiting cabinets for my 2240's!

    In a few weeks I'll have a pair of 4 cu ft cabs w/6" dia port 7" long for approx 40hz tuning.

    Crossover will be 500hz to 2441 on 350hz Edgar tractix horn with bullet tweeter on top.

    I will post when all the goodies come together and get installed.

    Regards, Ron
    JBL Pro for home use!

  15. #15
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    POS:
    The graph you posted is interesting.

    I have a couple of 2245Hs and was told they are not suitable for two-way systems since they cannot play flat much over 100Hz. According to your graph, this is not true, I suppose.

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