Below are the 12 steps to repairing the foam edge (surround) on a speaker. This example is using a 12 inch woofer being repaired with our G12F re-edge kit.


Here is what it looks like before we do anything to it.  The rotted foam edge needs to be removed so that you have clear access to the inside edge of the cardboard gasket.  Just scrape it away with your fingers.  Then take a razor knife and slowly separate the gasket from the steel frame.  This takes several passes with the knife so be patient.  

NOTE: Most of our kits come with replacement gaskets so you don't have to try and preserve the originals.


After you have removed the gasket you can clean the steel frame with either a wood chisel or small putty knife.  It's okay to have a glue residue on the frame, the objective is to get a smooth even surface.  You can also take your small razor knife and carefully scrape away the foam residue from the speaker cone's outside edge.  Same objective.  


We need to remove the dust cap so we can shim the voice coil.  Use your knife and while keeping the blade parallel to the speaker cone, slowly cut around the circumference of the dust cap.  Stop before you reach your starting point so that you leave a small portion un-cut.  This will  act as a hinge allowing you to flip the dust cap out of the way and then later put it back.


Take a small piece of tape and secure the dust cap up out of the way.

Note it is still attached by the small portion you left uncut.  

At this point the voice coil is now exposed so it is important not to get any debris in it.  


The objective is to install between 3 and 4 evenly spaced paper shims in the gap between the voice coil bobbin and the steel pole piece inside it.  You want the fit to be snug so that the cone doesn't move up and down easily but in fact stays where you put it.

There is no one shim thickness that works on all speakers.  Every speaker is different.  You can cut shims from magazine covers, or business cards.


The orange disc you see is called a spider. Together with the foam surround it keeps the voice coil centered around the steel pole piece.  It also contributes to the woofers compliance - or stiffness.  This spider should be flat.  Many times on older speakers it has begun to sag towards the magnet.  When you shim your voice coil set the cone position so that this spider is flat.



Now  put an even layer of the white speaker glue around the circumstances of the speaker cone as shown.  Also place a thin even layer on the inside edge of the new foam surround.  Use you finger to smooth the glue out on both surfaces.  Now  join the foam surround to the cone by carefully placing it on the glue joint and gently pressing it down.  Do not try to slide, pull, or stretch it in any way.  As it dries continue to press down where needed.



After you first glue joint is completely dry apply a thin layer of glue to both the steel frame and outside lip of the foam surround.  Carefully press the surround to the frame.  Do not attempt to pull, stretch, slide, or move it in any way.

Simply let it attach itself exactly where it falls.  It likely will not be centered in the steel frame, most woofers aren't.  Continue to press down until dry. You can use the gasket to help hold it down.


Once the glue has dried you can re-attach your gasket by covering the back side with an even layer of glue.  Once it is in place you can lay a board on top of it to hold it down or flip it over on the table and let it dry.

NOTE:  The gasket for this woofer is a one-piece and was the original gasket.  You can replace it with a inter-locking 4 piece gasket (new) that comes in your kit if you want.


After all the glue is dried it is time to remove the shims and check for center.  Gently push down on the cone in various spots and see if the voice coil rubs anything as it moves.  If not, your repair was a success.  If so, you'll have to start over.

After you have tested center, place a thin bead of glue on the dust cap and flip it back down into place.  Let it dry.


The final optional steps are called "dressing" the repair.  Apply an even layer of glue to both areas shown.  Use your finger to smooth it out. This is best done with the woofer on a turn-table or something that you can slowly spin.



The last step is to admire your work.  As you can see the white poly-acrylic glue dries clear making your repair hard to detect.

These polyether surrounds will last much longer then the original polyurethane that you replaced.

Give your woofer a few hours of playing time for it to break-in and enjoy another 25 years of service from it.


Our kits come with 2 new polyether foam surrounds, new cardboard gasket sets, paper shims, our special poly-acrylic adhesives, applicators and instructions.  We can also supply new dust caps.  



Decware is a trademark of High Fidelity Engineering Co.
Copyright © 1996~ 2010 by Steve Deckert