Article: How to Make and Use Loudspeaker Gaskets
1. Determine the Gasket Length
When constructing loudspeakers it is important, (for correct operation), that an air-tight seal is
achieved between the driver and it's cabinet.
Professional manufacturers often have custom gaskets provided for use with their drivers but it is rare in the DIY world that the purchase of drivers is accompanied by a gasket of any variety whatever. Occasionally a strip seal may be provided but not often. QTA Systems can provide closed cell, self-adhesive Neoprene or EPDM-Gasket strip seal in 3 widths and 2 thicknesses for DIYers to construct their own driver gaskets. For this particular application the two materials have identical sealing properties.
2. Partial Loudspeaker Gasket
The strip is coated with an aggressive / high tack paper-backed adhesive which
once applied may be difficult to remove, (depending upon surface characteristics), and works well with clean MDF.
As MDF is a fibrous material and wood particles shale off easily, reducing adhesion, remove all wood debris best.
Sticky tape is good for this, eg sellotape.
The thinner width materials, 5mm may be better suited for tweeters as the narrow tape width allows easier flexing / placement around smaller diameter cut-outs.
3. Gasket Ready for Splicing
(1) Without removing the backing strip, use the strip to measure around the edge of the cut-out. Note the tape is placed on edge for this measurement as it then flexes around the bends better. See fig(1). The strip should be cut marginally longer than the required length leaving about 20mm overlap of the two cut ends. This allows the use of a splice / diagonal cut through the tape giving a better air-tight seal than a straight butt joint.
4. Completed Gasket Joint
(2) Peel off the backing strip and position the tape in place, fig(2). Ensure the tape passes on the inner side of any screw holes used to fix drivers to their cabinet, (a source for potential leaks, as air can leak through the screw threads.)
(3) Using a sharp scalpel or craft knife make a diagonal cut / splice through both pieces of gasket material. fig(3). You really do need a sharp blade for this to achieve a good flush joint. Remove the waste pieces of material from both strip ends.
(4) Butt the two angled / spliced ends together and press the whole tape firmly into place. Fig(4) shows the final result.
Under normal compression the material will compress to around 10% of its original thickness, so, for a 5mm thick strip, this will compress to around 0.5mm. This information may be helpful if you are machining driver cut-outs for a flush fit, otherwise....... it's no real problem.