Fix a Speaker by Replacing the Foam Edge




About: Professionally I have been a summer camp counselor, a Draftsman/designer, salesperson, bicycle mechanic, laminate flooring machine mechanic, teacher, and designer of the OP Loftbed. Personally I am a human...

I have some 25ish year old speakers. I bought these new, back in the day and enjoyed them for many years. I sold them to my sister, when I moved out of the country and could not take them with me. A few months ago, my sister was cleaning up her house. She had gotten a new surround sound system, and did not need the speakers anymore. She asked me if I wanted them back and of course I did. After getting them home and hooked up, they sounded horrible. I took the grill off and noticed that the foam around the woofer had dry rotted away. Looking on the internet, I discovered that the foam edge of speakers usually only last ten or fifteen years. I also found that you can buy new foam edge kits and fix your speakers to be like new again.

In this Instructable I will show you what it takes to repair speakers that have broken foam edges.

Step 1: Tools and Supplies

The Foam Edge kit I purchased from a company called They supply all types of speaker repair kits, cones, dust covers, drivers, and the foam edge kits. The kit I bought was a perfect fit for my 12" Cerwin Vega AT-12 Speaker. It came with a pair of the foam edges, speaker adhesive, and printed out instructions.

The tools I used were:

Paper towels

Rubbing alcohol

Utility Knife (snap off blade type)

Flat screwdriver (for scraping)

A tool to remove your speaker from the cabinet (mine required a 5/32" allen wrench)

Step 2: Remove Speaker From Cabinet

Take off the grill. Remove the mounting screws. Carefully pull the speaker from the cabinet. The wires will be hooked up and pulling it out too far, could damage the wiring. Mark the speaker wire locations, to make sure you will be able to hook the wires up the same, when you reinstall the speaker.

Step 3: Remove Large Pieces of Foam

I did this while the speaker was still in the cabinet. My speakers were about 25 years old so the foam was very dry rotted and only a couple of large pieces remained.

Step 4: Remove Gasket

My speaker had a gasket over the foam edge. It was so old that it easily pulled off. If you needed to, you could use a screwdriver or utility knife to help coax it out. Save the gasket. You will need to put it back on later.

Step 5: Scrape Old Foam Off Frame

Using a utility knife, scrape the old foam and adhesive off the speaker frame. Rubbing alcohol will help loosen up the old foam and make it easier to remove. You could use a rotary tool, wire brush, or chisel, just be careful not to damage the speaker cone. I also scraped off the bottom of the gasket, I just didn't get any pictures.

Step 6: Remove Old Foam Off the Cone

Using a paper towel and rubbing alcohol, carefully remove the old foam and adhesive from the cone. The cone is relatively durable, but you want to support it from below to keep it from moving too much and damaging the voice coil.

Step 7: Test Fit the Foam Edge Piece

After the newly cleaned cone and frame have dried thoroughly. Test fit the new foam edge. Some kits need to be trimmed to fit properly. Mine fit perfectly without any modifying. They did cover the frame holes, but the mounting screws can be pushed thru the foam with just a little pressure.

Step 8: Glue the Foam Edge to the Cone

Apply a 1/8" bead of the speaker adhesive to the top edge of the speaker cone. Smooth out the adhesive with your finger. The adhesive that came with the kit is very sticky but it does give you time to align the two parts before it cures fully. Once everything is together and looks lined up, work the foam to the cone by squeezing them together with you fingers. You have to do this for a few minutes to make sure the adhesive gets a good bond between the cone and the foam.

Step 9: Get a Feel for the Speaker

After waiting one hour for the adhesive to fully cure, you are going to want to exercise the cone. By pushing the cone in and out of the voice coil you can get a feel for the speaker. If the speaker is not lined up properly with the voice coil, they will rub against each other an the speakers will not work properly.

Some speakers require that you remove the dust cover and use spacers to hold the cone centered in the coil. My speaker was luckily able to be repaired by just getting a feel for when the speaker cone was centered in the coil.

Step 10: Glue the Foam Edge to the Frame

Apply a 1/8" bead of the adhesive between the foam and the frame. Just like when you glued the foam to the cone, you are going to have to mash the foam to the frame to get the adhesive to properly bond. This time you are going to have to be careful and make sure the cone stays centered in the coil. You do this by occasionally pushing the cone down and feeling for the cone scraping the coil. If the cone does scrape the coil, push the foam on the frame until the cone moves freely in the coil.

Step 11: Glue the Gasket to the Foam Edge

After waiting another hour for the adhesive to fully cure, you are going to put a 1/8" bead of adhesive on the top outside of the foam edge. I eyeballed the alignment holes and then used a few of the mounting screws to make sure the holes in the gasket lined up with the holes in the frame. Once everything is lined up properly, flip the speaker over and let its weight hold the gasket on, while the adhesive cures for one hour.

Step 12: Reinstall the Speaker

Make sure you hook the wires back to the proper places on the speaker and then reinstall it back into the cabinet. put the grill back on and enjoy your like new speakers.

Step 13: Video

I made a video of the whole process.

As always, Thanks for watching and enjoy.



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    6 Discussions


    1 year ago

    I also used the SimplySpeakers kit to replace the 4 woofers on a pair of Wharfedale speakers (only 10 years old in my case). I could not believe how good they sounded after the repair! How do your's sound now?

    1 reply

    Reply 1 year ago

    Mine sound as good as new now. I gave an example before and after, in the video, but the audio in that video doesn't do it justice. I was very impressed. Thanks for your comment.


    1 year ago

    Seems those older speakers sound so much better then today's versions for some strange reason. I have a pair of Acoustic Research AR3a's that sound amazing still. Of course I replaced the woofers from the AR company once before I knew of the foam replacement ability like you posted. Bravo sir, Bravo. I hope you enjoy them for a longtime as well.

    1 reply

    Reply 1 year ago

    I have seen some small speakers that sound big, but I agree, quality big speakers sound better. I thought I was going to have to replace my woofers before I found out I could have bought the foam repair kit. Thanks for the comment.