Replacing absorber in dome tweeter

Many dome tweeters are equipped with a damper (absorber, absorbent substance) behind the tweeter dome. This is a piece of soft material. It must prevent reflections of sound against the magnet by largely absorbing this sound. This damper is often made of felt or foam, and hardens and decomposes over time. The absorption force therefore decreases, causing the sound quality of the tweeter to deteriorate. Furthermore, small particles of the damper can damage the coil of the tweeter. It is therefore advisable to inspect this damper on older tweeters and replace it if necessary. The damper is located behind the tweeter dome, in the center of the magnet. With silk dome tweeters, the damper is often visible from the outside:

To access the damper, the diaphragm must be removed from the tweeter's magnet. Screws often have to be removed for this. Sometimes the diaphragm is clicked onto the magnet. Sometimes the diaphragm is glued to the magnet, making inspection/replacement difficult.

Our series of guides describes several ways to remove the diaphragm from the magnet:

When the diaphragm is removed from the magnet, access to the absorber is available. The photo below shows the absorber in the heart of the magnet. It is in a slight state of decomposition. When we touch it, or remove it, it will shatter into countless small pieces. Because we do not want the air gap of the magnet to become contaminated with remains of the absorber, we have covered the magnet with painter's tape.

We remove the old absorber from the magnet. The painter's tape prevented any dirt from the damper from entering the air gap. We remove any adhesive residue from the magnet with some alcohol and a scouring pad.

Because the tweeter is years old, some dirt will have built up in the air gap over time. Hardened ferrofluid may also be present in the air gap. We therefore recommend cleaning the air gap with compressed air or a folded piece of painter's tape (sticky side facing out).

A dome-shaped, or flat, piece of foam or felt is then glued to the heart of the magnet. This soft material will absorb reflections. The damping material must not touch the dome of the tweeter, the tweeter dome must be able to move freely. When choosing the absorber, the diameter and height of the tweeter dome must therefore be taken into account. Once the absorber has been placed on the magnet, the diaphragm can be replaced.

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