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Thread: How to get real 16Hz...

  1. #16
    Niklas Nord
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    Aha
    what volume are we talking about for the 2245 and 2235 here?

  2. #17
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    It depends. Set the system Qtc for 0.5 to 0.7 and figure the required volume accordingly. A Qtc lower than 0.5 begins to enter the realm of infinte baffle as opposed to acoustic suspension. That is where the trapped air volume begins to no longer be able to add any restoring force to the moving assembly. I personally like Bessel responses (Qtc = 1/sqrt(3)) but Butterworths are maximally flat and can be quite nice (Qtc = 1/sqrt(2)). In reality it usually takes a pretty trained ear to be able to tell the difference between a sealed Bessel and a sealed Butterworth.

  3. #18
    Niklas Nord
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    Aha okej!
    Then a simple testbox will be the thing to try

  4. #19
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    You got it
    Test boxes are fun
    I can sit here and tell you all kinds of stuff until the cows come home but until you try it yourself and see what's going on you'll never get the experience first hand.

  5. #20
    Niklas Nord
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    What do you talk about?
    I dont own a cow ??????



  6. #21
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    Well, I guess we'll have to wait until mine come home then

  7. #22
    Member Paul D's Avatar
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    Sealed Boxes for 2245/2235

    I have 4 X 2245's in homebuilt cabs similar to the B460. I would like to know how your project turns out! My cabs are ported but
    I always thought about using sealed cabs. I have heard the Infinities with 4 X 12" woofers per side in sealed cabs and they
    were quite impressive.

    Do you think a sealed design would eliminate the boominess that ported enclosures can have?

  8. #23
    Senior Member Ralf's Avatar
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    Here is my theoretical result for 1 x 2242H

    What you think about?

    with 4 of these, I should get a maximum sound pressure of 133dB@50Hz (129dB@20Hz)...
    Attached Images Attached Images  
    16 Hz can not be substituted

  9. #24
    Senior Señor boputnam's Avatar
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    Re: Here is my theoretical result for 1 x 2242H

    Originally posted by Ralf
    with 4 of these, I should get a maximum sound pressure of 133dB@50Hz (129dB@20Hz)...
    Yikes!

    Can you hear me now...?
    Can you hear me now...?
    Can you hear me now...?
    bo

    "Indeed, not!!"

  10. #25
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    bx63

    Originally posted by Giskard
    Ralf,

    Looks decent. Are these 12 cubic foot volumes?

    Paul D,

    Sealed enclosures can also result in boominess if the sealed volume is too small for a given trasnducer (Qtc ~> 1.2). Vented enclosures are harder to "get right" hence the common misbelief that they are all boom boxes. They CAN be boom boxes, but they don't HAVE to be.

    hi,
    perhaps giskard can tell us if it's possible to use jbl bx 63 to extend bass response. perhaps he can give us schematics of this network
    Phil

  11. #26
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    Ralf,

    Looks decent. Are these 12 cubic foot volumes?

    Paul D,

    Sealed enclosures can also result in boominess if the sealed volume is too small for a given transducer (Qtc ~> 1.2). Vented enclosures are harder to "get right" hence the common misbelief that they are all boom boxes. They CAN be boom boxes, but they don't HAVE to be.

  12. #27
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    Re: bx63

    Originally posted by delahais
    hi,
    perhaps giskard can tell us if it's possible to use jbl bx 63 to extend bass response. perhaps he can give us schematics of this network
    I've posted schematics of the BX63 and BX63A numerous times. I've also uploaded the BX63 response for those who use BB6P. I've posted how to remove the low pass filter in the BX63, leaving just the EQ. You should be able to find the threads doing a search for BX-63 or BX63.

    If you want to try a fun little LF EQ try this - Eight Band Sub-Woofer Graphic Equaliser

    He has other fun projects as well...

    The top designers at JBL are not shy about using EQ. The latest crop of transducers such as the ME150HS, 1500AL, 1400ND, 1500FE, 2242H, etc. respond quite well to some LF and VLF EQ.

  13. #28
    Senior Member Ralf's Avatar
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    [QUOTE]Originally posted by Giskard
    [B]Ralf,

    Looks decent. Are these 12 cubic foot volumes?

    Hi Giskard,

    Yes, each box has exactly 12.143 cubic foot.

    Dimensions External:
    (HxWxD)
    1189 x 754,1 x 485,1 mm

    Wall Thickness 25 mm MDF

    Port Diameter 222 mm
    Port Length 538 mm (must be bent)
    16 Hz can not be substituted

  14. #29
    4343mod
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    Amazing thread. I'm compressed. Way out of my league.

  15. #30
    Niklas Nord
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    Since i have 4 of the 2245 and 4 of the 2235, there are really
    SOME things i could do with these..

    corner placed, and i tend to buy a TacT, so sealed boxes whaaa


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