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#### nathan225566

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Hello All,
I am trying to figure out how to build a transmission line box tuned to 30 hertz, so far i have found out that the port length needs to be roughly 37ft(37.6666667). What i need to know is how i can fit this port length into a box consuming 2.5 to 3 cubic ft? I have all the supplies i just need design help, in terms of actual dimensions. Length x width x height specs would be great, but any help is appreciated.

Thank You
Nathan

#### TrickyRicky

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Where did you get 37ft from?

#### Chaos

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37 ft is the wavelength for 30 hz, but a typical t-line would use quarter-wave, so you are really looking at 9.4 ft for the line length. Assuming the Sd of the sub is around 545 cm^2, then the volume of the line itself is much greater than 3 cu^ft.

#### nathan225566

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1130ft speed of sound through air divided by how i want my box tuned(30hz). I forgot the 1/4 part of wavelength for t-lines. I have done some research and i forget the equation but the port size should be equal to the volume displaced by the cone of the woofer, is this correct? If so, how do i calculate it? Another question is, after i find the correct port size, how do i keep my port's dimensions consistent with the t-line design throughout the box?

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Ignore the periods above, but the box will be something like that with the subwoofer close to the port.

#### nathan225566

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I measured the dimensions of my trunk, the maximum size box i will be building will be 36" x 18" x 15". I can increase height by as much as an inch but i would prefer to keep it 15. Anyone know what size my port for an idmax 12" d2V3 should be? I have not received my speaker yet so i do not know what volume it displaces...

#### TrickyRicky

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Those measurements are about 4cu ft enclosure so you have plenty of room. But it will be less once you put the woofer and the port.

#### Chaos

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Why do you need the speaker to look up its specs

#### nathan225566

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I can find the speaker specs but im not sure what specs are needed to figure out the volume displaced and then further find the dimensions of the port... help please...

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