Need to know how to build a slot-vented subwoofer box in a short amount of time? The idea behind an enclosed and sealed speaker box is to avoid the interference caused by negative sound waves. These are produced in the back portion of the speaker cone and cancel out the positive waves produced by the front portion of the speaker, thus causing reduction in sound effect. A ported or slot-vented speaker box enclosure is sealed from all sides and has one or two openings connected with a tube connected back inside the enclosed box. This way the size of the enclosed speaker box and the length of the tube help in controlling the negative waves being emitted from the speaker. When the speaker box and the tube are tuned properly, it adds the negative waves to the positive ones to amplify the sound.
To build a slot-vented subwoofer box, you will need:
- Xmax (this must be already there with your speakers. Check the speaker documentation for details)
- One sealed speaker subwoofer box
- Two feet of long two- to three-inch PVC conduit
- A calculator for the ported enclosure
- An electric drill and two- to three-inch drilling saws
- To build a slot-vented subwoofer box, first do some calculations. Enter the following details into the calculator for the ported enclosure: the volume of the enclosure and the size of the subwoofer and Xmax. The detail asked by the calculator depends on the brand or type of calculator you are using. For instance, some calculators may ask details such as number of drivers or speakers. After you have entered the required details, the calculator will display the diameter for the tube and port as well as the length of the tube to be used. In case the length displayed seems impractical, keep changing the input values till you get a practical result. For example, an impractical result would be when the tube length comes to be longer than the dimensions of the speaker enclosure.
Take a PVC conduit equal to the diameter as displayed after calculation. Using the saw, cut the pipe to the length arrived at after calculation.
Using a hole drill head, cut a hole in the front portion of the enclosure. Make sure the diameter of the hole is just big enough to fit the PVC conduit. Slip the conduit inside the new hole and push it till it goes inside completely. Make sure it is flat and doesn’t protrude from the front portion of the enclosure. The conduit should fit tightly. The part of the conduit coming out from the rear side of the enclosure should be just about two to three inches.
- Seal the enclosure around the subwoofer and slot vent. Let it dry for about 24 hours, and your slot-vented subwoofer box is ready.