DIY Building Bass Reflex Speakers

Written by teresa rodriguez
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DIY Building Bass Reflex Speakers
The usual size of a bass reflex speaker is 12 to 15 inches in diameter. (speaker image by Byron Moore from

If you are an audio fan, there few things more thrilling than duplicating the stomach-jumping low frequency effects of movie theatres in your own home. The fact that you can do so for relatively little money by building your own bass reflex speaker is even more remarkable. If you build a round subwoofer, the speaker can double as an end table, and you can create a piece of furniture in addition to a solid sonic foundation to your home theatre or listening area.

Skill level:
Moderately Challenging

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Things you need

  • Loudspeaker/driver.
  • Sonotube, 24-inches in diameter
  • Rasp or rough file
  • Binding posts
  • Birch plywood
  • PVC 90-degree elbows
  • ID PVC pipe, 4-inch
  • PVC cement
  • Flathead wood screws
  • Wood glue
  • Silicone caulk
  • Liquid Nails cement
  • Acoustic foam
  • 12-gauge speaker wire
  • Rubberised undercoating automotive spray
  • ID port "flares," 4-inch (optional)

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    Prepare the Project

  1. 1

    Buy a 12-inch loudspeaker/driver. This size is ideal for most audible low frequencies, and getting the best quality loudspeaker driver is one of the most important elements.

  2. 2

    Buy PVC pipe and PVC elbows. You need either 3-inch or 4-inch ID (inside-diameter) PVC pipe and four 90-degree elbows that fit the pipe.

  3. 3

    Buy Sonotube or other concrete form material from a building products store. For this project, you'll need 24-inch diameter Sonotube in a piece cut to 23 inches in length.

  4. 4

    Get three screw-on legs to mount on the bottom of the bass reflex speaker.

    Prepare the Tube

  1. 1

    Peel two inches of the waxy interior coating from each end of the 23-inch tube.

  2. 2

    Round the ends of the tube with a metal file to make insertion of the end caps easier.

  3. 3

    Spray acoustic damping material on the inside of the tube, but not on the ends that were stripped away.

    Prepare the Top and Bottom Pieces

  1. 1

    Use 3/4-inch birch plywood to make the end pieces. Cut three circles 24 inches in diameter for the bottom and top of the enclosure. Cut the fourth circle to 28 inches in diameter to serve as the tabletop.

  2. 2

    Glue two wood circles together for the bottom of the bass reflex speaker. Glue the larger circle to the remaining circle to create the speaker top. Use good quality wood glue and clamp the wood while the glue drys.

  3. 3

    Attach the top to the Sonotube. Insert the smaller diameter circle into the end of the tube and secure it to the tube with substantial amounts of wood glue. Add wood screws countersunk around the tube perimeter. Also apply silicone caulk around the inside seam to create a completely airtight seal.

  4. 4

    Cut out the bottom circles for the loudspeaker, the connection terminals and the ports. Use a circular saw or router to make the two 4-inch circles for the ports beside each other in the top third of the circle area. Create one 12-inch circle below the port circles for the loudspeaker. Cut two 1/2-inch diameter circles to the left of the 12-inch circle for the binding posts. Maximise space around each item.

    Speaker Assembly

  1. 1

    Glue PVC elbows to the PVC pipe with PVC cement. Cut two pipe lengths to 14 inches and glue an elbow. Glue a 3-inch length of PVC pipe into the open elbow. Glue an additional elbow pointing downward and glue a 10-inch length of PVC pipe that runs parallel to the 14-inch length. Make a second "port" in exactly the same manner.

  2. 2

    Attach these ports to one side of the bottom circles. Attach the loudspeaker to the opposite side of the bottom circle, using wood screws to secure it. Apply non-drying rubberised caulk around the speaker basket to create an airtight seal. Attach 12-gauge speaker wire to the terminals of the loudspeaker then run those wires through the 1/2-inch drilled holes. Connect the wires to the binding posts, apply glue to the perimeter of the 1/2-inch holes and insert the binding posts.

  3. 3

    Attach the bottom circle assembled to the tube. Use wood glue and flathead wood screws around the tube perimeter to do so. Then screw on the three feet to provide some distance for the speaker excursion.

  4. 4

    Finish the cabinet with textured paint or wood veneer, place it anywhere in the room, and connect it to an external amplifier for power.

Tips and warnings

  • With corner placement, you can expect greater than 110 dB output from this subwoofer design.

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