How to Fix a Dented Speaker Dust Cap in 15 min?


All brand new speakers look beautiful, but they lose this nice shape when their dust caps get dents.

Because this is a common issue, I decided to do some research on why car speakers get dents and how to fix this problem. Let me share the results with you.

In general, the best way to fix dented paper dust cap is to suck it out of the cone using a vacuum cleaner with low pressure. Fixing the plastic dust cap is similar, but you have to worm up the dust cap with a hair blower before using a vacuum cleaner. A dust cap made of aluminum is the most difficult to repair and often needs to be replaced.

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This article shows a few tricks on how to fix different dent dust caps and to protect cones from being damaged, let’s go through more details.

What Does a Speaker Dust Cap Do?

According to Wikipedia“The dust cap (also known as dust dome, or dome) is a gently curved dome mounted either in concave or convex orientation over the central hole of most loudspeaker diaphragms. It protects the inner mechanics (such as the pole pieces and the voice coil) from small particles (which can cause rubs) and other contamination”.

Most dust caps are made from the same material as speaker cones, but there are also paper speakers with plastic or aluminum caps. Thin aluminum is used most often in tweeters.

Some speakers, like active subwoofers, have accelerometers installed inside of the voice coils, and for these types of speakers, using dust caps is a must. Dust caps also protect voice coils and all wires inside of the speakers. It is crucial to protect the center of the speakers from any contact with foreign objects.

how to repair car speaker dust caps

Remember, do not ever touch inside of a running speaker; it can destroy the speaker to pieces, especially powerful subwoofers. Also, tapping on the running cone is not recommended.

Does the Dust Cap Affect Sound?

The reason to have dust caps in the speakers is not only decorative. They help to strengthen a sound that coming from the center part of the speaker cone. The center of the speaker makes higher frequency sounds and added, especially aluminum cap will help to make high tones stronger.

When there is an air gap between the cap and speaker cone, or when the cap is missing, you can hear the “chopping” like sounds.

The chopping effect is caused by the air going through the speaker between the cone and a magnet. Strange sounds are especially noticeable in subwoofers that are mounted in box enclosures and where is not much room for airflow, and they are similar to bass-reflex in the box.

Dented caps on the tweeters do not affect sound quality if damages are small. But when the cap in the tweeter is collapsed, then the tweeter may be damaged, and when you can start hearing raspy voices, that means either tweeter or the whole car speaker has to be replaced.

Make sure your speakers always have dust caps on them, and they are properly sealed, below are a few steps on how to fix or replace them.

How to Fix Dented Speaker Dust Cap?

If the covers on the speakers are dent, that does not mean you have to throw the speaker away. There are simple methods to repair the covers, so you do not have to spend extra money on the new speakers.

Fixing Dented Paper Dust Cap

Paper caps are the easiest ones to be fixed. The most effective method that works for me is to use a vacuum cleaner and just suck the dent cap out of the cone.

This method works well, but when you have a vacuum hose too close to the cap, it can rip off the dust caps from the cone, so be careful and do not use too much sucking pressure.

Sometimes after fixing paper caps, you may see some wrinkles on the surface. Wrinkles do not affect music quality, but for me, they do not look nice, and I would rather replace the caps.

Fixing Dented Plastic Dust Cap

To DIY repair dented plastic caps, you will need a hair blower and a vacuum cleaner. The first step is to blow hot air over dust caps. Make sure you blow air in circles over the entire plastic cup, and not over the one point. Having equal temperature on the whole surface will prevent further deformation of dust caps.

Different temperatures on the plastic can cause permanent deformation, so be careful and not overheat one side of the cover.

While worming up the cap, you can gently touch the plastic to check the surface temperature, because you do not want a cover to melt. When touching, you also check if the cap has softened across the whole area, but do it gently.

As soon as the whole plastic cap is hot and soft, the next step is to use a vacuum cleaner and suck a cover from the cone. Do not touch the hose to the cup when you use a strong vacuum cleaner or if you can, reduce the sucking pressure.

Although too much power can rip off the cup, you have to place a hose close enough to the cover so that air can suck the dented cup slowly to its original form.

Another way to repair dented domes is to use strong sticky tape. Just stick tape to the dented area and try to pull it off. It may not work for the first time, but after a few times, the dust cap should come back to its original form.

This method helps in many cases and is especially good for soft plastics in tweeters, where the vacuum hose may be too big.

To make sure that pulled domes have a nice smooth surface after the repair, you can use a hair blower to warm up the covers. Heating plastic may help material structure to come back to its original shape.

Fixing Dented Metal Dust Cap

Aluminum caps are the strongest of all types used in the speakers, and because they are stiff, repairing them is most difficult. Even if you can pull off the cap, its surface will still have visible marks and creases.

The better and faster way is to replace aluminum caps with the new ones. It will take less time than trying to repair them, and also the final effect will be much better.

How to Replace Paper Dust Cap on Speaker?

When you want to replace paper caps on your speakers, the steps below will help you do it quickly and without any problems. Below I recommend few simple tools that are available in any store. If you want them quickly, click the links and check them out on Amazon.

The whole replacement should not take more than 10 minutes, so let’s start:

  • Use a blade knife and cut through a damaged dust cap close to the original glue line. Keep a blade short to prevent any damages to the speaker cone or the line wires from the voice coil.
  • Remove any leftovers of the removed cover and make sure the glued area of the cone is clean and smooth without any debris on the surface.
  • Place a new dust cap on the cone and hold in the place, a good way to hold and place a cap in the center of the cone is to use masking tape.
  • Stick the dust cap with the speaker cone using for example MI 2000 adhesive. Apply a thin layer of the glue all around the edge, making sure there are no gaps left that may cause further not needed noises.
  • Leave the speaker with a replaced dust cap overnight in a ventilated and not too cold place to make sure glue will dry and cap will not move around.

After any repairs, I was leaving my speakers in the garage overnight, and by the next morning, they were like new. Remember to keep the speaker always with cone facing the ceiling while replacing a dust cup. This way, you will keep a cap in the center of the speaker without any risk of moving it before the glue will be dry.

How to Replace Aluminum or Plastic Dust Cap on Speaker?

Steps to replace plastic or aluminum dust caps are the same as for paper caps. The only difference is for glue the cap with the speaker cone.

You will have to use thicker glue than for paper caps and glue the area before locating a new cap in place. Also, use the thicker layer of glue to seal a dust cap with cone properly. The good elastic glue for plastic and aluminum caps is Adhesive Black Rubber Cement or similar, but cannot be too stiff.

How to Protect Dust Caps From Being Damaged?

Speaker dents are mechanical damages, and to avoid them, make sure your car speakers are always covered with grills. Especially twitters are sensitive to any contact with hard or heavy objects, and when damaged, their repair may not be possible.

If your speakers are not equipped with original grills, there are many aftermarket options available to choose from.

Many subwoofers placed in the trunks do not have grills and are also at the risk of being damaged. Make sure there is nothing close to the speakers that can damage them.

I hope this article was interesting and highlighted a few basics of speakers’ maintenance.

Martin

Welcome to ImproveCarAudio! I am Martin, and I love to write about everything related to car sound systems. I strive to provide the most accurate and helpful information about car audio through extensive research, as well as my experience with car audio installations.

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