audio car woofer
When you build your own box, it is cheaper in the long run than buying one outright. If you are unsure which set of wires goes to which speaker, you can use an alkaline battery (AA or AAA) to "pop" the speaker to help determine which speaker wires go to which speaker. Before drilling any holes, carefully check the area underneath the vehicle where the amplifier will be mounted to make sure it will not interfere with wires, brake lines, fuel lines, the fuel tank or any other objects that could be damaged.

car audio subwoofer enclosure
11. We must take this volume into account. The stuffing can make the box appear up to 40% larger to the driver.