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Overhauling JBL woofer with gasket
Some woofers are equipped with a gasket / decorative edge. This gasket often has an acoustic function (dampening reflections) and is intended to hide the speaker frame from view. Gaskets come in all shapes and sizes. Some are so carefully glued to the woofer that it appears to be part of the speaker frame.
A few examples:
Wharfedale EVO4 woofer with rubber gasket. This gasket is not glued but clamped into the frame. It can easily be 'plucked' loose with your fingernails (from the inside).
Infinity Delta 70 woofer with a precisely glued gasket. The gasket initially appears to be part of the speaker frame, but the foam surround runs under it. To replace the foam surround of the woofer, the gasket must be removed.
The JBL A306 woofer (from the TLX series), also with a precisely glued gasket. This gasket also appears to be part of the speaker frame at first glance, but the foam surround also runs under the gasket here. Here we outline the steps to take to overhaul this JBL A306 woofer and re-use the original gasket.
Before the foam surround of the JBL A306 woofer can be replaced, the gasket must first be removed. With glued gaskets, this is easiest with a (thin) knife. Slide the tip of the knife between the gasket and the woofer frame and carefully 'pry' the trim loose. Heating the metal woofer frame with a hair dryer makes prying it loose easier.
The gasket has now been removed from the woofer. The old foam surround can now be removed from the woofer frame.
Remove the glue residue from the gasket. If the contact surfaces are clean and free of grease, the gasket can easily be placed back on the woofer after replacing the foam surround.
To remove the glue residue from the woofer frame relatively easily, the residue can be weakened with alcohol, spirits or thinner. But be careful! Some woofers have a (paint) coating that can be affected by these liquids.
We often use a sharp (wood) chisel to clean the frame.
With this woofer, the foam surround is glued to the back of the speaker cone, so the old foam residue must be removed from the edge of the cone. We used a cotton swab dipped in a solvent for this. It is advisable to support the cone with one hand opposite the spot that is being cleaned.
Once the speaker cone is clean, the glue can be applied to the edge of the cone.
Also apply glue to the inner glue edge of the foam surround. Then glue the foam surround behind the speaker cone.
With a syringe, glue can easily be applied between the outer edge of the foam surround, then the foam surround is glued to the frame of the woofer.
Now apply glue to the glued surfaces of the gaskets, and glue the gasket to the woofer. The gasket is often glued to the foam surround of the woofer.
The JBL A306 woofer fitted with a new foam surround, with a replaced gasket.
© Good Hifi VOF