Introduction: Replace Dry Rotted Speaker Surrounds With Cloth Replacements.
If you're like me, I can't pass up a nice pair of speakers sitting in the side of the road. More often then not, the reason they're sitting there is either because they're blown or in many cases, suffer from having dry rotted cone surrounds. These are the foam or rubber flexible rings that enable the speaker cone to flex back and forth, thus producing sound. Sub woofers tend to move quite a bit, so once the surrounds become too brittle, they can crack or disintegrate with age.If that be the case, then there's actually not much wrong with the speaker. It just needs to have these rings replaced. This Instructable will show you how you can replace these by making your own surrounds out of scrap cloth, thus enabling you to renew sometimes expensive speakers and have a fantastic stereo for next to nothing.
Step 1: Preparing the Speaker.
Before we get started, a word of warning. I've repaired quite a few set of speakers using this method, and in most cases, it works great. I once found a $1,200 pair of speakers in the trash, repaired them with this cloth method, and they were probably the best sounding set of speakers I owned. But if you didn't find yours in the trash, or they are your prized possession, then you might want to consider other options. You can in fact buy replacement speaker surround kits. They typically cost under $30 and don't take a huge amount of skill to do yourself. Additionally, since I never actually hear these speakers in their "prime" I have no idea if they sound ' as good' as they did after my repair. The repair I have here is also less cosmetically attractive as a more professional repair.
But if you're as cheap as I am or have little money to spend on speakers, this repair is for you. So lets get started. The Victim for this job is a nice JBL 10" subwoofer. First, remove the speaker from the cabinet. Secondly, gently remove the old surround from the cone. About 90% of the speakers I find use foam. This stuff usually just crumbles away. This speaker is a bit nicer and uses rubber. This speaker as many others has thicker foam pieces glued over the top of the edge of the surround.They typically come out in several pieces. Use a knife of some sort to gently pry them off. Then pull the rest of the surround off.
The next step is probably the most tricky. Making the new surround. See if you have any old scraps of cloth laying around. The best cloth to use would be a synthetic blend, tightly woven, and smooth.I've used all sorts of cloth, including canvas.But you want to use something that's flexible enough to allow the cone to move freely. Use the speaker to trace the shape of the surround to fit. Secondly, measure how far in the surround reaches towards the center of the cone. Usually the surround glues to the very edge of the cone. But since you're using cloth, you will want a tad more holding power. So measure inwards about 1/8" from the outer edge of the cone. Use a compass to mark the inner part of the cloth circle to cut out.
Once you've cut the surround out, you will want to make slight compound cuts all along with edges of the cloth, about every 1/2" or so. You do this so the cloth won't crease or wrinkle as it is being installed.
Step 2: Glue the Surround in Place
Next, we glue the surround into place. For some reason, I find that wood glue works incredibly well for this. It dries pretty quick and is highly tacky. Use a small brush to put a thick layer of glue around the edge of the metal speaker frame. Gently place the cloth surround on this frame and then press go around the edges, embedding it in the glue.
Now put a thin layer of glue onto the bottom of the foam pieces. Make sure you line the first piece up with one of the screw holes. Apply a bit of glue to its mating surface- the edge where the edge of the cloth surround now sits. Repeat this process and glue the foam pieces all the way around.
For the next step, get a small amount of water and mix up a watered down slurry of wood glue and water. Brush on a thin layer of glue on the outer edges of the cone where the inner edge of the cloth surround will attach. Using the same slurry mixture, brush the edge of the cloth to the edge of the cone. The watery glue will absorb into the cloth and cone, mating them together . Go around the whole cone and brush on a thin layer of glue to bond the cloth to the cone. I generally fins this works well in direct sunlight as it will set the glue quickly.
With both inner and outer edges of the cloth surround glued into place, Set the cone to dry in the Sun or somewhere warm. It takes around 5-6 hours to mostly dry, overnight to dry thoroughly.
Step 3: Finishing Up.
The last step is to paint the cloth surround. This is done to seal the cloth. Your speaker creates a sort of vacuum in the speaker cabinet, so you don't want air to escape past the cone. Since we used cloth to replace the old surround,which is porous, we want to seal it up. To do so, you'll need a can of spray paint- preferably black.If you don't care about the cosmetic appearance of the cone, you can just skip the next step. If you want it to look at least decent, cut out a circular piece of cardboard that covers the cone. Then use masking tape to mask the decorative ring on the edge of the metal speaker frame. Some speakers don't have this ring. Then apply a thin layer of paint. Don't apply a heavy layer because you'll make the surround too stiff. Just a couple of passes and you're done.
Wallah! Let it dry and install and see how it sounds. The good news is that cloth will never wear out, thus if they sound great, you'll have a set of speakers that should last indefinitely.