[DO IT YOURSELF] How to repair woofer dust-caps, with just a few euros and in 10 minutes time

Product: dust-caps
Cost: variable, depending on material
Author: Lucio Cadeddu - TNT-Audio Italy
Published: march, 2024

We have already discussed, on several articles, the problem of repairing damaged speakers without resorting to professionals in the field. Sometimes the value of the loudspeakers or drivers does not justify the expense of the intervention of a specialized lab, an expense which could easily exceed the value of the loudspeaker itself. Here we have addressed the problem of do-it-yourself re-foaming, with a brief mention of replacing the dust-caps. In this tutorial we deal in more detail with the problem of repairing or replacing the dust-caps of woofers or midranges, given that nowadays kits that fit to many different drivers can be easily found on the market at bargain prices. With a few euros more, on specialized sites like this one, you can purchase dust-caps made of the same material as the speaker membrane (plastic, carbon fiber, etc.).

Step 1. If the damage is not serious enough to require replacement, you can try two shortcuts: using a vacuum cleaner to which you can connect a nozzle the size of the dust-cap itself or use a small pin with which you can try to lift the sunken part of the dome (I assume you know kids' fingers are biologically attracted by domes). In both cases, delicacy is a must, so not to cause a more serious damage.

Step 2. If the dust-cap is irreparably damaged or refuses to revert to its original shape again, after a few attempts as in the previous step, it must be replaced. Fortunately, dust-caps of all sizes are easy to find and, by carefully choosing where to buy, you can solve the problem with just a few euros. Here on Aliexpress, for example, you can find dust domes of different diameters at extremely low prices, and the quality is very good. You can choose the one that best suits your driver. If there is no exact size, it is better to take a slightly larger one. The key word to enter on Amazon, Aliexpress or Ebay to find them is "speaker dust-cap" or "woofer dust-cap". Let's get started, here's how to proceed step by step.

First, remove the old dust-cap, using a sharp cutter. The dome is, in the vast majority of cases, usually glued in place. With a little care you can detach it from the speaker membrane without causing damage. You need to use a steady hand and a lot of delicacy, trying to slowly lift the glued edge of the dome. Pay attention to avoid cutting the membrane!

At this point you will be exposed to a scenario you see in the pic: the voice coil of the driver is clearly visible. This is a sensitive area, and it is essential that it is as clean as possible. Even the smallest particle of material can slip into the air gap of the coil and cause problems. Make sure everything is clean. If not, a small handheld vacuum will help cleaning up the area. Obviously, any residues of the previous glue must be removed from the speaker membrane, taking care not to damage the membrane itself.

It's time to glue the new dome. Any adhesive such as clear Bostik or classic UHU will work fine. Quick adhesives (such as Attak) should be avoided for two reasons: as they are too quick they do not give you time to reposition any incorrect attempt and, secondly, they are not the best choice for gluing porous materials (e.g. cellulose pulp), and they also tend to create a too rigid glued area. Place a little amount of glue where the mark of the old one was, if the dust-cap is exactly of the same size, or a little further out if the dust-cap is larger in diameter. For aesthetic reasons, obviously, the replacement dome must have the same or slightly larger diameter than the old one, so that the previous contact area can be covered. Also, spread a thin layer of glue on the edge of the new dome and leave to dry for 5-10 minutes, so that the solvent evaporates a little; faithfully follow the instructions for the type of glue you are using.

Join the parts gently, making sure you have centered everything well. Press gently to make the rim of the new dome adhere well. Bear in mind that the driver is designed to move back and forth, even with a certain violence, so light pressure will not do any damage. Remove any excess of glue with a cotton swab or other similar device. Bear in mind that very little glue is needed to ensure an excellent hold. Finally, to ensure that the parts join well and uniformly along the entire edge, it is a good idea to place a glass or cup (upside down) so that the edge of these rests on the edge of the dome see pic). Leave to dry for 24 hours and you're done.

Remarks

The dust-cap serves to protect the voice coil assembly of the speaker from...dust, in fact. It does not have a precise acoustic function, except in certain cases. This means that, realistically, the sound of the speaker, especially if it is a woofer, will not change. If the replacement dome is heavier or lighter than the original, the weight of the moving mass will increase or decrease, and this has some effect on the response of the speaker, especially in dynamic conditions. However, this is a repair, and it is impossible to expect perfection. This repair makes sense when the original woofers, for example, are no longer available or their value does not justify the intervention of a specialized laboratory. In any case, an original woofer with the dust-cap replaced is better than a different woofer in place of the original one, both in terms of sound quality and resale ability of the speaker.

We recommend replacing both dust-caps, to avoid aesthetic and behavioral differences in the speakers between the two channels. The aesthetic result will depend greatly on the initial state of the membrane and its material, which may or may not absorb the glue differently, creating areas of different colours. Cellulose pulp membranes, from this point of view, are the most difficult.

DISCLAIMER. TNT-Audio is neither a shop, nor a HiFi company or a repair laboratory for HiFi components. We don't sell anything. It is a 100% independent magazine that neither accepts advertising from companies nor requires readers to register or pay for subscriptions. If you wish, you can support our independent reviews via a PayPal donation. After publication of reviews, the authors do not retain samples other than on long-term loan for further evaluation or comparison with later-received gear. Hence, all contents are written free of any “editorial” or “advertising” influence, and all reviews in this publication, positive or negative, reflect the independent opinions of their respective authors. TNT-Audio will publish all manufacturer responses, subject to the reviewer's right to reply in turn.

DIY tutorial on dust-cap repair or replacement

Ten minutes of work, within everyone's reach

Remarks