Replace Dry Rotted Speaker Surrounds With Cloth Replacements.




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.



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35 Discussions

I am a sound equipment tech.

This fix can work, but I have some suggestions for making this DIY chore better.

Try searching up a surround replacement kit. If you cant find a reasonably priced surround kit for your make and model driver, take some accurate measurements and look for a suitable generic one on fleabay. Also actual speaker glue is available online for reasonable prices and its already black and it thins/removes with M.E.K. usually.

If you can't find one or just want the total diy route for fun read on.

1. Some Pro speakers come with concentrically corrugated cloth surrounds coated with sealer but that would be supremely hard to replicate at home. So be sure to give extra fabric between the frame and the cone to allow free movement through the whole travel of the cone.

2. I would use a more flexible and waterfroof glue. Rubber cement is used a lot in antique radio repair on paper cones.

One might experiment with some other things:

Fabric tack glue, Liquid electrical tape, Plasti-dip, butyl rubber caulking etc.

Most of these can be thinned with the correct solvent for consistency or a fabric sealer coating.

check the "Danger- contains..." label on the back to see what would thin effectively. Sometimes Acetone, M.E.K, or laquer thinner work for different materials.

I can't guarantee results with these, I'm just thinking of things that should have the right flexibility and adhesion.

Just used this method on all four infinity door speakers in my durango. I used an old pair of jeans and all purpose cement. I also covered the cone and use some flex seal I had to rubberized the cloth. Man they sound great. Nice fix for free using what I had available.

1 reply

It was actually pretty quick and easy. Hardest part was waiting for them to dry.


2 years ago

My Dad and I fixed my subwoofer with hot glue using the same method you showed us with the cloth. It worked great!!

I admire your creativity, but this is the long, difficult, and wrong way down a simple path. Just order foam and refoam the woofer as intended. Changing the surround material to something else will change the compliance. I order foam surrounds in bulk from MAT Electronics and they cost almost nothing. Foam surrounds are intended to be a "consumable".

3 replies

fast eddie, I agree that the best solution is to get suitable replacement foamrubber surrounds, but unfortunately it is not readily available for many speakers. I have four Wharfedale woofers which need new rubber surrounds, and nobody stocks suitable replacements (I've literally searched the world over via the internet.) For cases like mine, a DIY-approach is the only way left.

There is another option if you can't find replacements although i don't know how well this would work as i've only used it for other things like building custom gaskets and buttons,you can actually get some liquid silicone or say some silicone caulking

a sheet of nonstick material like say parchment paper or wax paper or a baking sheet whichever you prefer to call it

and a rubber spatula and create a thin rubberized sheet of silicone to use as a replacement rubber surround

or you can buy some of this and glue it in place since it reflexes well,although i would rather go with the rubberized liquid silicone method of making one on a baking sheet with silicone caulking since you can customize it more by using different non stick materials as a mold including the bottom of a ceramic plate even though not non stick still works if you let the silicone dry and slowly peel it
and on the plus side it actually looks like the shape of a rubber surround for a speaker

and if the rubber surroud on your speaker is too big to mold out of the bottom of a plate you can always use the bottom of a planting pot as something to mold a surround out of the best thing is that planting pots come in different sizes so you're pretty much covered.

Umashi, hi, thanks for the very detailed suggestion! Fortunately, I eventually found suitable surrounds at Simply Speakers in the USA. They cost me about $70 dollars and almost as much again for shipping, but they did the job perfectly. I'll keep your suggestion in mind for future projects, and I'm sure it will be of use to many other people!

This was perfect! I used a nylon 30% cotton 70% blend fabric and sealed the fabric with really watered down wood glue mixture for the last step (no spray paint laying around) and now my old speakers are working very nicely...and it didn't cost me a dime! I had been looking online for re-foaming kits and repair options when I stumbled across your post in my search. I just really wasn't interested in spending $30 for a repair kit for these particular speakers....what a lucky break for me! Thanks for sharing, you made my day :)

hey your idea is just pure genius! can you tell me if jeans is a good enough cloth or should I use something else?

Remember that mass(weight) of the moving parts effects its acoustic properties. Too much glue will add weight to the cone and reduce the resonant frequency, possibly adversely effecting the cabinet tuning. Also, subs are long-excursion drivers and need a rolled surround, which would have to be pre-molded to the right shape, and carefully fitted so the voice coil doesn't rub. Fortunately, subs generally give more magnet gap than wide range drivers, but it's still pretty critical.

i am repairing my jamo cd power 15's right now, but the foam is gone there is nothing the foam ontop of the cloth really nessecary ? or can i be don without it aswell?

the only thing missing is the proper alignment of the voice coils in the woofer before gluing the edges. I believe that others had mentioned this as well.

I think you're kinda' missing the point of this instructable. Its about fixing speakers basically for free. Not to be confused with fixing speakers using the "right" materials- as in spending money for new surrounds, etc etc. In fact, I make a disclaimer at the very beginning of this post that basically says exactly what you're saying- which is that you CAN buy repair kits for these and that if you own a prized set of speakers then you might want to consider other options. But if the speakers came from the trash... well that's everyone's call. So yes- I concur with you that there is a right way and a wrong way. This is perhaps technically not the right way but it has worked fairly well for me. But again- anyone reading this should realize that yes- you can ruin a set of speakers using the cheap-o cloth method. So proceed with caution.

Anyway, the speaker I repaired in this post has been alive and kickin' ever since the repair. Over and Out.

Would you be worried about this keeping the Dry Rot in your house though? I hate to sound a little over cautious, but the spores of our dry rot was such a nightmare to get rid off that I would want to spray the speaker with some anti-fungal stuff...

i like getting speakrs of the side of the road too look at my sound system

sound system.jpg

I've always been really interested in speakers and only recently got my first set for a pretty neat sum, as I just a student. The rubber has gone on them so they produce a raspy noise at mid levels.
This instructable has given me a summer project for after exams. I look forward to trying it. Thanks man; I'll let you know how I do!

you sed, '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.' ... but then you use spray paint to 'seal it', which is also gonna make it stiffer, less flexible, eh?
i just looked up 'felt' and it is 'non-woven', so it may not be appropriate, eh? but what speakers did you use canvas on, eh? tent or tarpaulin grade? def not flexible.
back in the day (dont know bout today) mfrs used rubber or foam... for a reason,eh?... trade-off between durability and expense vs. flexibility and rigidity... (i assume both rubber and foam are effectively impermeable... )

flexibility and rigidity seem to be the essential characteristics, and it is a balance point. Too rigid, the cone doesnt move, too flexible, it moves too much in unwanted ways... Trying to achieve the balance (of control of the movement of the speaker cone in the 'in and out' direction, without any side to side, with 'free movement' of the speaker cone in that direction.)

Your description (above) of the 'best cloth' says to me 'microfiber', which is 'synthetic, tightly woven, and smooth', But it is also VERY flexible... maybe too flexible, eh? The spray paint 'seals' AND stiffens it... How much in not enough, just right, and too much?... how do you judge...

What do you think of using silk?...

This is already overlong, but two more things. Back in the late 80's I had a couple of good quality JBL cabinet speakers which had the woofer surrounds deteriorated... I did not feel qualified to do the job myself, so I paid a local high end audio shop to do the repair... They never did sound right after that, sounded like they were 'stiff' or 'sticking'... I concluded, then, that the surrounds were too 'stiff'... Now, with what i have learned since, I think it is likely that they replaced the surrounds, but didnt remove the 'dome' to insure that the coil was moving freely...

I have a pair of Altec-Lansing 411-8A LF 15 Subwoofers which i bought from a friend a number of years ago, with blown ( 'gone' ) surrounds... look up the specs... recent offerings for these speakers on Ebay, with blown surrounds are at about $450 each... I only need one subwoofer for my home, i dont even want one in my car... So i fix both, keep one and sell one...

I dont wanna use a 'generic' kit for a 15 inch speaker for these babes... so I sent an email to A-L asking to get surrounds. they promise an answer in three days...



Thanks for posting this instructable. I am like the author and hate to see good speakers go to waste because they lack a little TLC. I have a pair of Sony speakers that have traveled with me since the beginning. I hate to admit it but I kept these over a pair of RTR's that were in need of refoaming. So as a tribute I am using this home method to repair the Sony's. Only I am doing a few things different. I went out an bought some heavy duty canvas and stretched the heck out of it then made my measurements and cuts. Then instead of using wood glue I am using a "Aleen's Flexible Stretchable Fabric Glue" I am using it as a way to hold the fabric in place but also to keep the fabric air tight for a better vacuum effect. I am going to let the glue dry for 24 hours and then test. From what I can see using the cloth as a surround is identical to how Sansui built their speakers back in the 70's. I'll keep you posted as to how they sound. Thanks again for posting this.

I am repairing my 12 inch ess speakers surrounds. My wife suggested interface as she uses it in dress making. I have found that the nature of the interface means no cuts on the outside every half inch and no need to use a slurry to paste to cones. It is flexible enough to hopefully make sure the required movement of the cone will not be hindered.They are drying at present. They look quite professional .