DESIGNING YOUR POLK EX SUBWOOFER ENCLOSURE STEP BY STEP
1.) How much room do you have to work with in your car or truck?
2.) Which of the above enclosures sounds the best to you?
When designing your subwoofer enclosure, the first thing you need to figure out is just how large an enclosure will fit in your vehicle. When an enclosure is going in the trunk of a car, you first need to measure your trunk to find the maximum height, width, and depth available. Pay attention to trunk hinges and tension bars. If your enclosure is going in an area other than a trunk, make sure you check for similar obstructions. After measuring, subtract 1.5" from each dimension. This compensates for the thickness of the material you use, and will give you your usable (internal) dimensions. Record these dimensions in the
FIGURE 5.
17 1/2" 16"
space below for future reference.
Maximum dimensions | Usable dimensions |
Height:__________inches | (Minus 1.5 inches)=______inches |
Width:___________inches | (Minus 1.5 inches)=______inches |
Depth:___________inches | (Minus 1.5 inches)=______inches |
34"
35 1/2"
10" | |
11 | 1/2" |
| |
Usable volume=________cubic inches |
Usable volume=________cubic feet |
Multiply your usable Width x Height x Depth. The product will be the usable (internal) volume of your enclosure in cubic inches. Divide this number by 1728 (the number of cubic inches in a cubic foot). This will give you the internal volume in cubic feet. Divide your internal cubic feet by 2 (only if you are using a pair of EX subwoofers). Compare this number to the chart on page 14 of this manual. Choose the recommended enclosure which is closest in size. Now that you have all of your needed dimensions, you can begin cutting your wood. From the above chart you can tell how big each piece of wood should be. Here’s a sample enclosure.
Maximum dimensions | Usable dimensions |
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Height: | 17.5 | inches | (Minus 1.5 inches)= | 16 | inches | |
Width: | 35.5 | inches | (Minus 1.5 inches)= | 34 | inches | |
Depth: | 11.5 | inches | (Minus 1.5 inches)= | 10 | inches | |
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| Usable volume= | 5440 | cubic inches | |
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| Usable volume= | 3.15 | cubic feet | |
By looking on the chart at the bottom of page 14 of this manual, you’ll find that this usable volume is slightly more than double the recommended volume for a single EX12, in either a sealed or vented enclosure. Assuming that you will be using a pair this will work out well. If you are using a single subwoofer, you can cut your width in half. Since we will be using a pair of EX12 subwoofers for our sample enclosure, we now need to determine the center divider displacement and the resulting total usable volume. This can be figured out by multiplying the height x depth x thickness of the divider, and subtracting that number from the total usable cubic inches. Using the example above yields the following result:
[5440 in3 - (16" x 10" x 3/4")] = [5440 in3 - 120 in3] = 5320 in3 total usable volume.
You now have all the dimensions you need to begin cutting out your wood. The illustration above shows a diagram of the enclosure with all the panel sizes that need to be cut.
After you have cut all of the wood, it’s time to start assembling your enclosure. Before you assemble your enclosure there are a few things we recommend doing. You will need to cut out the hole for your EX subwoofer and your terminal cup. The terminal cup is a connector that allows you to plug and unplug the wires from your amplifier into the enclosure. You may want to have a friend help you with assembly since it’s hard to hold the pieces together and assemble them at the same time. When building your subwoofer enclosure, we suggest that you use wood glue in combination with wood screws for the strongest joint. We also suggest that you use one screw about every three inches along the seams of your enclosure. Assemble the enclosure as shown in the above diagram, but leave one side off. We suggest that you leave off the baffle board. This will allow you to seal your enclosure more easily, and an
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