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Thread: DIY-project: JBL Kebnekaise S4365

  1. #91
    Senior Member Odd's Avatar
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    Carpenter Sweden.
    A few years ago there was an old nice man with a workshop on the west coast who made some enclosures for me.
    I do not know if he is still working, but the website is still there.
    JOA Snickeriverkstad AB
    43XX (2235-2123-2450-2405-CC 3155)5235-4412-4406-4401-L250-18Ti-L40-S109 Aquarius lV-C38 (030) 305P MkII

  2. #92
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    Quote Originally Posted by Odd View Post
    Carpenter Sweden.
    A few years ago there was an old nice man with a workshop on the west coast who made some enclosures for me.
    I do not know if he is still working, but the website is still there.
    JOA Snickeriverkstad AB
    Thanks.
    I actually asked them about making a simple testbox some time ago, and got this answer:


    Tyvärr kan jag inte hjälpa dig med detta projekt, då jag inte arbetar med MDF längre.



    Med vänlig hälsning

    Ian Garrett

    JOA Snickeriverkstad AB
    "I am not working with MDF anymore".

    Is this the same guy you used Odd?

  3. #93
    Senior Member Odd's Avatar
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    Yes it was Ian.
    43XX (2235-2123-2450-2405-CC 3155)5235-4412-4406-4401-L250-18Ti-L40-S109 Aquarius lV-C38 (030) 305P MkII

  4. #94
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    Anyone having a guesstimate how much volume (L) the 1501fe woofer will reduce the box inner volume?

  5. #95
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    Quote Originally Posted by bubbleboy76 View Post
    Anyone having a guesstimate how much volume (L) the 1501fe woofer will reduce the box inner volume?
    This calculator gives me 5.34 liters for the woofer.

    https://www.diyaudioandvideo.com/Cal...ent/Help.aspx/

  6. #96
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    Quote Originally Posted by Ruediger View Post
    I did a quick lookup in Thiele's paper.

    An alignment which fits is a QB3 somewhere (interpolated) betweeen alignments #2 and #3.

    Alignment #3 results in f3 = 53 Hz, Vb = 49 Liters, fb = 42 Hz.

    That is a ballpark figure. You can vary that a bit, but not much.

    Ca. 50 Hz from a 50 liter box is quite attractive.

    Ruediger
    I have started to sketch on another alternative LF box design. The intention with this design is a "minimal" sized box, that can be placed deep into the room corner, if I should want to.

    The box shape was first outlined as a rectangle with 40cm sides (because I want about 56cm total width, the hypotenuse), then I cut away triangles to make it just fit the woofer, and reach 50L net volume.

    Also a less expensive shape, without the rounded backside.

    I used the 49 litres volume (suggested by Ruediger) as target, and added one litre for "safety". So 50L. I tried a speaker simulator program called Basta!, that also suggested about 49 litres as optimal box volume for this woofer.

    The rationale for this design is that I know I will probably end up with subwoofers in the end anyways, so these speakers will not have to play full range. And I also would like to try my corner-speaker-concept "all-in". This design is intended to be able to dock 100mm damping (like basotect) to the sides when put in the room corner.

    Flodstroem, can you help me simulate where I should put the bass port, and if I can use my 69mm ports when aiming for the Ruediger suggestion of f3 = 53 Hz, Vb = 49 Liters, fb = 42 Hz? How much damping on the walls would be good? I have 40mm thick sheep wool that can be used.

    (In the sketch the liter numbers for bracing and woofer volume are interchanged by mistake)

    If I choose this kind of box, my thought is to first try it as closed box, to see if the corner-gain + dsp will be enough. And add BR-port later, if it is needed. In the closed scenario the box would be filled with damping.

    Comments and thoughts are welcome!
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  7. #97
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    You still need to interpolate

    <quote>

    I did a quick lookup in Thiele's paper.


    An alignment which fits is a QB3 somewhere (interpolated) betweeen alignments #2 and #3.

    Alignment #3 results in f3 = 53 Hz, Vb = 49 Liters, fb = 42 Hz.

    That is a ballpark figure. You can vary that a bit, but not much.

    Ca. 50 Hz from a 50 liter box is quite attractive.

    </quote>



    You still need to interpolate between alignments 2 and 3. I did not do that. The figures I gave should show the magnitude, not more.


    I attach a flowchart which should give you the same cabinet parameters as an interpolation between alignments 2 and 3.


    Ruediger
    Attached Images Attached Images  

  8. #98
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    It is over my head to do that interpolation.

  9. #99
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    FWIW, My understanding of the research paper that begat the profiled ports currently employed by JBL was that flare made little difference to real world tuning - was dictated by csa of the narrowest point x actual length. from the paper 'Maximising performance from loudspeaker ports' ;
    "An initial samples of 6 port tubes, all of length 120mm and minimum diameter of 60mm were made with NFR’s of 0,0.125,0.25,0.5,0.667,and1.0. In addition, all profiles had a small 12mm blend radius on both ends to avoid sharp edges, as well as a 140mm inner baffle for symmetry.
    Unexpectedly, port tuning frequency was only weakly dependent on flare. Clearly, theport length and minimum throat diameter appear to be the main determinates of tuning
    . As port flare becomes more pronounced, the end correction, as typically calculated based on the radius at the mouth, overestimates the reactive air mass present. A better way topredict tuning appears to be basing the length correction on minimum throat diameter instead of maximum diameter." This method proved to be accurate to within 2%.

    An observation on the bass enclosure design is perhaps as you are going to the trouble of a curved back you may be missing an opportunity to slope the top to more closely mirror the underside of the vertical horn.think B&W, This would allow the box to be slimmer slightly more elegant from the front while keeping your volume.

  10. #100
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    Hlaari, I have been receiving fake emails in your name from: hla08@outlook com
    Be careful! They tried to make me send money to bank-account in Benin, Africa, in your name.
    Maybe your email has been hacked? They knew things we have talked about.
    I think you should change your email password, to start with (I will do the same).

  11. #101
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    Some small details added.
    Some internal measurements can be seen in the attached pdf.
    Attached Images Attached Images  
    Attached Images Attached Images

  12. #102
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    Quote Originally Posted by cooky1257 View Post
    An observation on the bass enclosure design is perhaps as you are going to the trouble of a curved back you may be missing an opportunity to slope the top to more closely mirror the underside of the vertical horn.think B&W, This would allow the box to be slimmer slightly more elegant from the front while keeping your volume.
    I have been thinking about phased/angled top of the box, like Array series. But I do not like the looks of that.

  13. #103
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    Quote Originally Posted by bubbleboy76 View Post
    I have been thinking about phased/angled top of the box, like Array series. But I do not like the looks of that.
    No problem;-)

    Are you planning to include a plinth/feet/base?

  14. #104
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    I will try soft feet decoupling the speaker low frequencies from the floor, in the end, when I know the exact weight-distribution of the speaker.

    The only problem with that approach is maybe this:

    Quote Originally Posted by gtimbers View Post
    You will eat the bass kick immediately if any enclosure movement is allowed. The woofer kicks really hard and if any energy is consumed moving (rocking) the enclosure due to it not being properly coupled to the floor, you will lose bass kick and impact. The proper use and need for spikes (or equivalent) is not BS. It is based in sound theory and is easily demonstrable.
    I will start with them on casters, I think.

  15. #105
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    Quote Originally Posted by bubbleboy76 View Post
    I will try soft feet decoupling the speaker low frequencies from the floor, in the end, when I know the exact weight-distribution of the speaker.

    The only problem with that approach is maybe this:



    I will start with them on casters, I think.
    Sorry,your response to the above quoted comment regarding spikes from Greg Timbers is to put your speakers on wheels. Ok good luck with that.

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