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How to Get Proper Enclosure Box Measurments?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=9622
Printed Date: July 12, 2025 at 3:02 PM


Topic: How to Get Proper Enclosure Box Measurments?

Posted By: Signal
Subject: How to Get Proper Enclosure Box Measurments?
Date Posted: February 16, 2003 at 8:11 PM

From these specs does anyone know how to calculate the size of a box i need to build height, width, and depth.
I wanna know how to get the proper measurements, please show me what to do to get the proper measurements.


this is the specs for JL 12 W7
Dimensions:
Frame Diameter: 12.5 in. (318 mm)
Mounting Hole Diameter: 10.5 in. (267 mm)
Mounting Depth: 9.5 in. (241 mm)
Overall Depth: 11.25 in. (286 mm)
Magnet Diameter: 7.5 in. (191 mm)
Pole Vent Clearance: 0.75 in. (19 mm)
Displacement: 0.14 cu. ft. (3.03 ltrs)

Enclosure Recommendations:
Sealed Range: 1.25 - 1.625 cu. ft. (35.4 - 46.02 ltrs.)
Recommended Sealed Volume: 1.375 cu. ft. (38.94 ltrs.)
Fc: 44.7 Hz
F3: 40.4 Hz
Qtc: 0.792
Ported Range: 1.5 - 2.25 cu. ft. (42.5 - 63.7 ltrs.)
Recommended Ported Volume: 1.75 cu. ft. (49.56 ltrs)
Recommended Tuning: 32 Hz
Port Type: “Slot” ports are recommended. See Data Sheet for detailed in



Replies:

Posted By: the12volt
Date Posted: February 16, 2003 at 8:39 PM

Signal wrote:

Enclosure Recommendations:
Sealed Range: 1.25 - 1.625 cu. ft. (35.4 - 46.02 ltrs.)
Recommended Sealed Volume: 1.375 cu. ft. (38.94 ltrs.)
Fc: 44.7 Hz
F3: 40.4 Hz
Qtc: 0.792
Ported Range: 1.5 - 2.25 cu. ft. (42.5 - 63.7 ltrs.)
Recommended Ported Volume: 1.75 cu. ft. (49.56 ltrs)
Recommended Tuning: 32 Hz
Port Type: “Slot” ports are recommended. See Data Sheet for detailed in

To calculate volume, multiply length x width x height. The recommended enclosure volumes are included in the specs you listed.

Example: Lets say you have a particular space that is 30 x 16 inches in area in your vehicle where you'd like to place the enclosure that should be between 1.25 and 1.625 cu. ft. I'll use 1.5 cu. ft as a target volume for a sealed enclosure in this example and start by dividing 1.5 cu. ft. (or  2586 cu. inches) by (30 inches minus the thickness of material (both sides)). 2586/(30-1.5) = 90.736842105263157894736842105263.

Now divide 90.736842105263157894736842105263 by (16 minus the thickness of material (both sides)) to calculate how high you have to make it to be 1.5 cu. ft. in volume. 90.736842105263157894736842105263/(16-1.5) = 6.2577132486388384754990925589837.

So you're final external dimensions would be 30" x 16" x 6.29" for a 1.5 cu. ft. enclosure made of 3/4" material that will fit in the desired location in your vehicle.



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Posted By: Signal
Date Posted: February 17, 2003 at 8:09 PM
Thanks for the info, but what if i just wanna build a box for this woofer with these specs. How would i do that???




Posted By: the12volt
Date Posted: February 17, 2003 at 9:26 PM

Hi Signal, I used those specs in my example to fit into a desired location. There is no absolute starting dimension for a box. You will have to start with a desired dimension of your own as I did in my example. The location in which you want to place this box should give you that starting point/dimension.

If you are not trying to build a box to fit into a particular space and only want to build a 1.5 cu. ft. square box made of 3/4" material, the box's outside measurements would be: 15.25" x 15.25" x 15.25" (1.5044 cubic feet)  To convert cubic inches into cubic feet, divide by 1728 and always remember to subtract the thickness of material to get your interior volume.

https://www.the12volt.com/caraudio/boxcalcs.asp#rec 



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