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    L-Shaped Port - Slanted Box

    I want to design an L-port in a box with a Slanted REAR side... like the one below



    How am I gonna make the calculations? Both WinISD and Bass Box 6 Pro do not have an option for L-shaped port... If anyone could help, desired Vb is 2.48 cu.ft. and Fb 38Hz.







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    Re: L-Shaped Port - Slanted Box

    I think you are going to have to go by port area and actual port volume.
    So you calculate the the volume of a standard 90 degree port with your
    given port area.

    The trick is to to calculate your actual port volume on the angled box.

    Port area and port volume are what you need to know.

    uh....I think.



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    Re: L-Shaped Port - Slanted Box

    You could probably calculate the p1 port volume using the angled box
    calculator on bce. The p2 volume looks standard rectangle.



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    Re: L-Shaped Port - Slanted Box

    I don't think it's just 2 volumes that I have to match... Watch the green volume that appears...





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    Re: L-Shaped Port - Slanted Box

    you would be better off having the port horizontally across the bottom and have it
    go up the rear wall of the enclosure...

    or use aero / abs ports



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    Re: L-Shaped Port - Slanted Box

    Quote Originally Posted by THUMPPER View Post
    you would be better off having the port horizontally across the bottom and have it
    go up the rear wall of the enclosure...

    or use aero / abs ports
    or since you clearly dont have room for this, how about from the back of the top, curving down? As in the top of the blue section would be part of the opening




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    Re: L-Shaped Port - Slanted Box

    THUMPPER, I need to use as little height as possible... Aero tubes would be fine, but in the other thread they told me that the diameter is too small... Anything bigger would require to corner that tube...

    Rashaddd, now, that's an excellent idea But can u show me how? :S
    Last edited by DOOM_NX; 11-05-2008 at 12:20 PM.




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    Re: L-Shaped Port - Slanted Box

    Would you use this page to create your box?

    http://www.reaudio.com/speaker_box/LPort_Box_Calc.html

    Bass Box 6 Pro and this page results do not match...




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    Re: L-Shaped Port - Slanted Box

    Quote Originally Posted by DOOM_NX View Post
    Would you use this page to create your box?

    http://www.reaudio.com/speaker_box/LPort_Box_Calc.html

    Bass Box 6 Pro and this page results do not match...
    I would use is only after you figure out how far off your square 90 degree box
    calculations is it in terms of tuning frequency and net displacement.

    Then create your slanted box to match the RE calc's version of the numbers
    you are looking for.

    ie:

    your 90 degree box has 2.4 cubes net after woofer and port wood displacement
    at 38hz

    RE calc shows that box is 2.6 cubes net at 36hz.

    Well screw RE, your calculations are correct. Now create a slanted box with the
    appropriate port width that gives you 2.6 net at 36hz from the RE numbers.
    Because you know when RE says 2.6 at 36hz; it really means 2.4 at 38hz.

    Do you understand?



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    Re: L-Shaped Port - Slanted Box

    I see I see... The same way when I entered MTX's suggested ported enclosure measurements, RE calc showed 2.534 cu.ft. and 31.3 tuning freq. I altered the dimensions trying to keep the same vb and fb and came up with this front slanted box.



    I need a rear slanted box so I moved port pieces in this way:



    Is it the same?




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    Re: L-Shaped Port - Slanted Box

    Quote Originally Posted by DOOM_NX View Post
    I see I see... The same way when I entered MTX's suggested ported enclosure measurements, RE calc showed 2.534 cu.ft. and 31.3 tuning freq. I altered the dimensions trying to keep the same vb and fb and came up with this front slanted box.



    I need a rear slanted box so I moved port pieces in this way:



    Is it the same?
    Yes.
    Same "Green" area, and same port area.

    Do the math, though. Stop being lazy. Section it off into 3 sections, 2 rectangular prisms, and one pyramid prism.

    EDIT:: actually, the second one, the back part will be a rhombus prism.



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    Re: L-Shaped Port - Slanted Box

    Quote Originally Posted by DOOM_NX View Post

    How am I gonna make the calculations?
    before all of these silly programs people designed boxes using a piece of paper and pencil.



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    Re: L-Shaped Port - Slanted Box

    Thinking about this, if you made the end of the port (inside the box) at the same angle as the slant it would even out the port length. I'm not good with diagrams so someone else would have to sketch it up if they understand what I mean




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    Re: L-Shaped Port - Slanted Box

    Here's some of my mad mspaint skillz.





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    Re: L-Shaped Port - Slanted Box

    OK sorry for getting on everyones nerves but all I do the last 3 days is sketching boxes in Sketchup and messing around with BB6 and similar programs.

    Now, I finally ended up in the box below. Given that the one RE calc suggests and this one are the same, I think this is the box to go.



    If everything is right I'm going to get the cutout plans and start building it... Thanks for your answers and patience again.




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