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Thread: DIY-project: JBL Kebnekaise S4365

  1. #46
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    I updated the concept a bit. Now it is M2-box volume and port tuning. This is better I think.
    I also reduced wall-thickness to 21mm to reduce weight.
    BR-port lenght should be someting similiar to M2, if using the same volume, tuning and port-diameter, right?
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  2. #47
    Senior Member Flodstroem's Avatar
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    What dimension of the

    Width 560mm

    Height 1000mm
    Depth 310mm


    have you changed ?
    Flodstroem

  3. #48
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    Quote Originally Posted by Flodstroem View Post
    What dimension of the

    Width 560mm

    Height 1000mm
    Depth 310mm


    have you changed ?
    Hard to say... I redesigned the main-concept to get 20L more volume.
    The test-box is not valid any more. I thought you left me hanging

  4. #49
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    I will not do a testbox, I changed my mind.
    I will go straight for the dessert.
    Flodstroem, there will be no more changes now. Can you calculate approx. port-lenght for tuning to 20,25 and 28Hz for the new concept?

  5. #50
    Senior Member Flodstroem's Avatar
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    Yes I can do some plots, have actually done some............. you are not left hanging
    Flodstroem

  6. #51
    Senior Member Flodstroem's Avatar
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    I have done the sims. What I can say is that the 20Hz dont look any good. >100 watts less usable power resistance, X-max reaches at approx 30 Hz while the higher tunings manage 500 watts easily and X-max reaches below the tuning frequency at approx 21-23 Hz

    SPL is a bit different between the tuning fr. You will need some boost below 60-70 Hz I believe. But if using an active xover this isnt a problems.

    What factor/variable is most important for your project?

    28 Hz port length 4.5" (2 x 69 mm)
    28 Hz port length 12" (2 x 103 mm)
    25 Hz port length 5.75" (2 x 69 mm)
    25 Hz port length 14" (2 x 103 mm)

    This is the plot of the 20 Hz tuning @ 375 watts and 2 x 69 mm tubes
    1501fe 20Hz 2x69 mm 350 watt Xmax at 30 Hz.pdf
    Flodstroem

  7. #52
    Senior Member Flodstroem's Avatar
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    Btw, the ports (center of) should be located 32" below the top end (internal). Woofer (center of) approx 8-10" below top end (internal).
    If you shoos to place the ports on other locations then I cant guarantee from lack of reflection/standing waves etc........
    Flodstroem

  8. #53
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    Thanks!

    Hard to say which factor is most important. After EQ and room gain I would like to be able to play down to 25hz, with +9db gain on 25-135Hz relative higher frequencies, if possible.
    I live in apartement and do not play extremely loud.

    I can start with about 25Hz tuning then, and later shorten the ports if 28Hz seems to be better.

  9. #54
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    Quote Originally Posted by Flodstroem View Post
    Btw, the ports (center of) should be located 32" below the top end (internal). Woofer (center of) approx 8-10" below top end (internal).
    If you shoos to place the ports on other locations then I cant guarantee from lack of reflection/standing waves etc........
    Those positions seems hard to fulfill with a box of 850mm external height. And I want minimal woofer/horn CC-distance.
    I will put woofer as high as possible, and the ports as low as possible, on the front baffle.

  10. #55
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    Quote Originally Posted by bubbleboy76 View Post
    Those positions seems hard to fulfill with a box of 850mm external height. And I want minimal woofer/horn CC-distance.
    I will put woofer as high as possible, and the ports as low as possible, on the front baffle.
    You cant come closer than approx 7.5-8" so a 8-10" distance from the top end seems to be most practical or have I missed something?

    Btw, havent you specified a hight for the cabinet to 1000 mm ?
    Flodstroem

  11. #56
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    850 height
    560 width
    rounded bakside
    see latest pic

  12. #57
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    Some more detail added.
    BR-ports has to be 150mm up from bottom to be able to be covered by original 4365 grill.
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  13. #58
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    Nice!

  14. #59
    Senior Member Flodstroem's Avatar
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    I have done simś for your last model of cabinet.

    You could use either the 28 or 25 Hz tuning. Both of them manage approx 500W power down to at least 21 Hz. But you will need a high pass filter to protect the woofers from frequencies below that point.

    The sims says port lengths of:
    28 Hz = 5" (127 mm)
    25 Hz = 6" (153 mm)

    2 ports and a dia of 69 mm in each cabinet placed 226 mm up from bottom (28 Hz tuning)
    But, thats not optimal for the 25 Hz tuning. Best port location for the 25 Hz tuning is 277 mm up from bottom for to avoid unwanted reflections.
    Its up to you to make a choice...........

    Woofer placement as high as possible.

    Also the simś shows (but not here) a better efficiency than with your suggested 103 mm tubes. Your choice of the 69 mm seems to be
    optimal in theis case.

    Here you could see a 500 Watt plot/sim for the 25 Hz tuning and X max.

    1501fe 25Hz 2x69 mm 6 in port Xmax at 21 Hz at 500 watt.pdf
    Flodstroem

  15. #60
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    Wow! Thank you very very much!

    I updated the concept with your changes.

    Was there pages missing in that last report?
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