How to Refoam a Speaker With an Inverted Dust Cap

Written by jessica jones
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How to Refoam a Speaker With an Inverted Dust Cap
Purchase a speaker foam replacement kit that contains foam, shims, dust cap and gaskets. (audio hi-fi and speaker image by Stanislav Halcin from

Over time, the foam on your home audio speakers may begin to dry out, tear or fall off, leaving sensitive electronic components vulnerable to dust and other debris. Replacing the foam helps protect these components while preserving the look of the speakers. Home audio speakers typically have a dust cap and gasket, or outer ring, to hold foam in place and prevent dust build-up. It is best to replace both the foam and dust cap to ensure optimal protection.

Skill level:
Moderately Easy

Things you need

  • Replacement foam
  • Dust cap
  • Gasket (optional)
  • Small utility knife
  • Plastic or wood shims
  • Tape
  • Glue

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  1. 1

    Remove the speaker from the speaker enclosure and unplug all wires. Mark "positive" wires and "positive" wire terminals with small pieces of tape to distinguish positive from negative wires, if not already marked. Refer the to owner's manual and wiring chart as necessary. Plugging wires into the wrong terminals may result in shorting out the speaker's electrical components.

  2. 2

    Remove old foam and glue using a small utility knife. Cut a small hole in the centre of the dust cap to remove. Continue cutting until you reach the edge. Pull out the dust cap with your fingers. Make small cuts across the dust cap to avoid cutting the speaker cone and voice coil housed underneath.

  3. 3

    Place at least 4 plastic or wood shims (1/8-1/4 inches wide) around the voice coil and magnet pole piece. The shims help keep the speaker cone in place while refoaming. The voice coil, magnet pole and cone are located under the speaker cone which is visible after removing the dust cap. Refer to the owner's manual to identify speaker parts. Purchase plastic or wood shims online or at your local hobby or hardware store.

  4. 4

    Place new foam over the speaker to determine fit. Cut oversized foam with scissors to fit properly in the speaker frame.

  5. 5

    Apply a thin line of glue around the speaker cone. Press new foam gently on the cone to attach. Apply a thin line of glue around the speaker frame. Press new foam gently on the frame to attach. Allow glue to dry at least 24 hours before rewiring speakers.

Tips and warnings

  • Some speakers have an outer ring or gasket that you will have to remove before taking off the old foam. Use a small knife to pry outer rings and gaskets off speakers.
  • Do not use chemicals or cleaning solvents to remove old foam or glue. These chemicals may damage the internal parts of the speakers.

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