18'' Speaker Recone-Repair

Hello, let's find out how to recone/repair burned, overloaded or torn speakers.

Do you like loud music?

-No: You might still like speakers and stuff, keep reading and learn something today :)

-Yes: In this case, you might need this badly someday. Same as I burned a speaker, so can you.

Why pay somebody to repair it if you can do it at home and it is not as big of a deal as you might think.

First of all, how do you know your speaker is burned out?

-You might hear it making popping or clicking sounds, or any uncommon sound that does not seem like the right one. Listen to some music that you know well, so you know how it should sound.

-Make sure you exclude outer factors (bad cables, amplifiers, or other equipment) by replacing them, so you know it's the speaker that's gone bad.

-Once you think the speaker is bad you should check it physically. Gently press the membrane down either pressing on multiple spots or on hardened spots like the cap edge to make it move straight down and back up.

If it is moving freely it might still be ok. Measure the resistance and if it matches it's designed resistance it should be ok.

If you hear or feel the coil scratching (not moving smoothly) you can be sure you need to recone it.

At this point you can freely cut it with a knife and pull it out to check the coil visually. Attached 2 photos how in my case the coil is visibly damaged either by some contamination or by overheating. Needs replacement.

The tools you need are basic. Some knives, screwdrivers or scrapping tools, will most likely do the job. An air compressor is highly recommended.

What you need at this point is a recone kit. As speakers are all different, the only way to be 100% sure you are getting the right one is to get the original one from the speaker manufacturer or a matched one. For known brands they should be easily available, as for some uncommon brands getting those might be trickier. Mine is a B&C NW100 4ohm and it cost me about 70€ (80$) for the recone kit which is way less than getting a new speaker.

Next, you need glue. Usually, you don't get it in the recone kit.

In best case you take slow (40min) and fast (5min) epoxy + rubber contact glue. If you don't have them, you can also do it with a middle cure time epoxy, so you don't need to buy both.

The water treatment was included in the recone kit in my case.

Cleaning the old stuff out is a verry important step.

Clean the old glue and membrane parts out by scrapping the surface is not such a big deal. Just keep the air gap for the coil covered while you do so!

Cleaning the air gap is a different story. You have to be more then 100% sure it is cleaned if you want success. There might be small metal parts inside that are holding on the magnet and won't go out unless you force them. Easiest way to clean the gap might be blowing high pressure compressed air from different ways to clean the non metallic parts, as well as move metallic parts to a visible spot. Once you see the metallic contamination get it out with double sided scotch tape or similar sticky tapes. If some burned coil varnish is inside you might need to scrap it out with a plastic card.

Repeat the process until there is no contamination visible also after you blow the air threw the gap.

Apply mid or slow cure epoxy where the spider and membrane lay down. The epoxy should not be too liquid. If it is you might need to thicken it with some cotton flock powder or microbaloons. I added some pigment to make it dark.

Make sure you turn the membrane, so the wires face the terminals.

Once you put down the membrane in place make sure you centre it with centring shims between the coil and magnet on the inner side. They should be included in the kit. You must spread them 100% equally by thickness. 1 layer around all circle, or more layers if needed around all, but not more on one side than the other.

Press the membrane down to soak in the epoxy. Apply rubber glue (thick layer) all around where the rubber spacer stays and place it in. Make sure you align the screw holes.

Also check if there are no air gaps between the spider and the housing. The glue should fill them all. Same on the upper cone part.

Cover the speaker wit a flat surface and put on some weight. I used a glass plate and another speaker for the weight.

Let it dry for 12h minimum or more as per epoxy (the one you used) cure time.

Take the shims out and check if the membrane and coil are glued correctly and move up/down freely. If they do, you did a great job.

Glue in the protective cap. Use fast epoxy to prevent it from flowing inside while curing.

Solder the wires to the terminals same as they were before.

Apply water protective treatment with a soft brush. It's like painting. This will make it water resistant as well as a nice-looking shiny surface. Like factory new! Wait for it to dry completely. You can even apply 2 layers if there is enough of it supplied in the kit.

Test it and enjoy the music!