How to Refoam your Woofer

During the seventies and eighties, either planned obsolescense, poor engineering, or short-sightedness caused speaker manufacterers to use a type of rubber surround for drivers that deteriorates with age. Perhaps you have a pair of speakers that show the classic grainy, dirty looking speaker surrounds or maybe even have holes in them already. I got a pair of old Advent Heritage speakers from a guy for free because the surrounds were shot. The previous owner tried using silicone caulk to stave off the inevitable to no avail.

For about ten bucks a driver, you can replace the foam surrounds if you have some patience and determination.

There was a time when the quality of a manufacturer's equipment was what determined their success, rather than the amount of money they spend on advertising. While those days are past, much of this aging Hi fi equipment can be found on craiglist or freecycle for a song. At best, they are ready to go with a little dusting. Sometimes, however, the drivers need to be refoamed. Would you like to get started?

Rock on!

Step 1: Stuff to get:

Obviously you will need an old pair of speakers. The foam surround kits are not inexpensive so make sure you are getting a decent pair of speakers to begin with. Also the paper cones should move freely and they should still make sound when played. All the drivers should play. If they have been energized a lot with the surrounds damaged, the voice coil could be abraided away, shorted out, etc. Those should be avoided because I don't think that's an easy fix. Today we are working on a pair of Advent Heritage speakers. They are not the classic Advents and were produced after Jensen bought the company and ruined it. However these speakers, despite, their shortfalls, sound really good to my ears. The cabinets are pecan and clean up really well.

Materials:
Screwdriver
Razor blade, hobby knife, or scalpel
Stiff brush or toothbrush
Can of air
Speaker refoam kit http://stores.ebay.com/GeoAli-Vintage-Stereo-and-More
The kit I purchased included the glue, paint brushes, shims, speaker edges, and instructions.
Wood care products of choice (I'm using Howard's Restore a Finish and orange oil cleaner)
Clamps, c-clamps or the like if you have beauty rings to clamp into place.
Hair dryer or heat gun if your speakers have vanity rings around the basket ring.

Comments

[Homibeef]

You got lucky that only the foam was shot. Heritages are nice speakers. Good tutorial too.

[emergencydpt.com]

Thanks for your comment. I agree, the Heritage speaker is great. I keep my eyes pealed for them on craigslist. Never know when a pair will show up for twenty bucks!

[jason9922]

Yeah brother you did a really good job of explaining the entire thing. The only few things that one might add if they were to do this on a newer speaker is just how you can sometimes on some subwoofers / woofers use a hair dryer to loosen up the glue on the dust cap, especially if the woofer is made of poly and not paper. You can heat up the cone with a hair dryer, NOT A HEAT GUN lol, and then you can gently pop off the dust cap wich 99% of the time is held in place with a small piece of 2 sided tape plus the glue around the edge. But your speakers were older style so of course you didn't even have to mess with that. But you did a really great job and when you were done you couldn't even tell you replaced them. How did they sound?

[sypher]

Awesome, something rather useful, something I was wonder myself. I will more than likely use this in the future.

[MTJimL]

Really fine Instructable! Like the personal touches. Now, maybe you can tell me where to find replacement drivers and how to tell if they will match the cabinet's acoustics. Keep up the good work.

[MTJimL]

Love the bit about scented air. Also, your spelling and grammar are a refreshing exception to the Instructables norm.

[chamunks]

Well thanks for the Ible I have about 4 pairs of some ultra fantastic somethings that i cant recall the name of as of right now but in their day they were absolutely boss at cranking out the acoustical joy.

[nurdee1]

On your first picture in your first step you have some of your picture note boxes inside others. Because of this you can't read the notes in the inner boxes.

[br7930]

Great Job
Thanks
Beauty rings ---again
After I refoam I put the rings back on covering the edge of the foam where it was glued - correct.
It looks like they hold the foam in place - but I know its the glue.
BR

[flame boyyyy]

love the dog picture lol ugly woofer foam

[rippa700]

Brilliant instructable thanks. I was about to abandon an old 1970's pait of Boston Acoustics that have knackered foam. They have sat unused for 4 years since I saw the damage as I couldn't bear to part with them. Now I don't have to. Thanks.

[hell_raiser_1]

Is it plain white glue?? or theres something special about it?? I say this because I need to refoam a pair of 10" infinity's and I can buy the foam for 4 bucks each!!!

[emergencydpt.com]

It looks like plain white glue to me. I suspect it's elmers but I have no way of testing.

[hell_raiser_1]

Exactly !!!!!!, I did some testing with an old piece of foam, clear drying-yellow glue (which is exactly the same as the finest Elmers but with a higher viscosity), and glue it to a metal and I couldn't believe my eyes, I wasn't able to take it apart without tearing out the foam. Great Instructable !!!!!

[3VIL G3NIUS]

 i believe they used foam because then the driver would not require any breaking in like rubber does... nice instructable! never heard of anyone calling them beauty rings though.

[emergencydpt.com]

 Thank you for your comment.  Re: beauty rings. What are they called?  Enlighten me.  I'm afraid I'm ignorant on their real name.

[3VIL G3NIUS]

 no probs, im happy to comment :-).
i dont know what they are called either. not many speakers have them now (not the cardboardy one anyway) i dont think they even have a official name so beauty rings they shall be :-)

[bobbyrae]

Beauty rings?  Not exactly sure what is meant by that.  I can see what you are doing with them, but I would like a definition, and, can they be bought somewhere?

[emergencydpt.com]

Hi. The beauty rings are just plastic covers that go around the perimeter of the driver.  I don't believe they have a function.  I've never seen them for sale.   If you break them getting them off then you may try getting them from the OEM or parts express.  You could even leave them off.  They are just decorations.
Rock on.

[sibuadvancetech]

good information for the speaker and keep up your good work

[emergencydpt.com]

Thanks.

[Zak]

My woofers had the dust cap integral with the cone (Dynaudio). The instructions that came with my surrounds told me to glue the rings to the cone first. After that, the foam would be clamped to the frame with 4 clothespins. Then, testing by pushing on the cone. By off-center pushing it can be determined that the voice coil is centered (scratching starts at the same amount of off-center-ness). Then the glue is applied where clothespins are not. When that dries, the clothespins are removed and the remaing bits glued on.

[70scollect]

Hello Foxtrot, Please reply to the PM I sent you. You appear to have the know how to fix these. I really need help and advice on a Advent 1000A repair project I have. Thanks for any help!

[Yerboogieman]

What if you have steel dust caps with Really good adhesive and will not cut? And even harder to put a knife under to peel off. They are indent caps.

[emergencydpt.com]

I believe in the case of steel dustcaps, you skip shimming the voice coil assembly to the plinth and instead ;sequentially glue the edge around, making adjustments to keep it moving freely. You first glue opposite sides, then work your way around in sections. Kind of hard to explain.

[dz0004455]

if i only need to refoam the edge do I have to remove the dust cap and the foam or just the foam?

[jac hawk]

fantastic very very very helpful

[Guitar_slave]

Great instructable thanks man i have searching for this cind of instructable for a long time TNX. good work

[fsm1982]

I am looking for this at years... You save the world! =D

[emergencydpt.com]

Yea. World saved!

[dan2]

if the crossovers are old it would be a good idea to replace the caps - caps lose their capacitance after a while and this changes your crossover frequency.

[Foxtrot70]

dan2 - Your absolutely correct about the caps. I rebuilt 3 Advent Video Beam 1000A projection tv's since the units were built around 1978 the cap values changed so much circuits like focus, AC filtering on the main power supply were all most useless. It was expensive replacing them but the final result is a tv with a 8' screen, it can also be converted into a rear projection of two sizes 8' and 10'. They are a joy to watch everything is as big or bigger than life.

[kelraith]

What breed of dog is that on the left?

[emergencydpt.com]

That's Teddy. He's a Yorkshire Terrier. This picture is from when he was about 11 or 12 weeks old I think. He had fluffy hair, giving him a teddy bear appearance, hence the name. He's possesed by the devil. He barks, bites, chases children, pees in the house...I'll be happier when he gets a little older; passed the teenage (dog) years. The other dog is a Mini Schnauzer. Very calm, well behaved. Unlike most of the other Mini Schnauzers I've seen, he doesn't bark at all, or very rarely anyway. Thanks for your question. My next instructable will be on Yorkshire pudding. ha ha. -Spencer

[junits15]

Nn interesting repair technique is if the paper on the speakers is ripped, some clear or black nail polish fixes it, I've done this many times and it works with no decrease to quality. This actually works believe it or not! (BTW I'm a guy don't ask questions!)

[emergencydpt.com]

Ha ha ha. Sounds good to me! No questions asked. -Spencer