Building Tips

A General Guide to the Construction of Speaker Boxes

Whoever builds their own speaker boxes has a large advantage compared to commercially manufactured boxes as the design and finish is yours alone. They can simply be modified to suit yourself and your decor from the original plans. To what extent you want to spend on your speaker project is up to you, as little or as much as desired to achieve the result you want. You should however already have given some thought to the quality of the speaker drivers in relation with the quality of speaker box (and materials) you will build. They must be in some sort of comparative quality level to achieve the best results from the speaker drivers.

Housing

With building speaker boxes, the material and tool expenditure is relatively small. Circle jigs, veneers, glue, screws, clamps and the like are usually found in hardware stores. For very complicated cabinet shapes and cuts, you should obtain the services of a carpenter to handle that part of the construction. For all types of woodworking, please ensure you have suitable safety equipment, such as safety goggles, breathing masks and hearing protection.

Material

With your choice of materials, the surface texture of the housing is already determined. For solid wood boxes furniture grade timber is necessary. Select pieces without warps, knots or holes. For lacquered or painted finishes, very clean surfaces are necessary. Often the best results are obtained when MDF sheets are used. This material consists of compressed wood fibres and adhesive. The advantage of MDF sheeting for speaker boxes is in the very high density and ease of cutting / shaping. Before the lacquer or painted finish, the surface which can be worked on should be primed very thoroughly sanded with a gradually smoother grade of sandpaper. Only then will the result be satisfying to you. For true wood finishes, veneers are recommended.

Please Note: With all MDF and chip boards, please pay attention to any chemical emissions for a healthy environment. Also with lacquers and paints there are environmental safe products. Ensure adequate ventilation when painting.

Other materials for the building of speaker boxes include: marble, cast stone, slate, fibreglass laminate, concrete, Plexiglas, metal, casting resin, plastics and much more besides. The main thing to note is that the speaker box walls are strong such that as few resonances and vibrations can occur as possible. These resonances arise by the strong and rapid change of air pressure inside the housing during use.

If the speaker box walls can resonate due to the movement of air internally, each wall of the housing can have one or more resonant frequencies. These walls are hence acting as a sprung moving mass, similar to a speaker driver and will cause coloration and distortion of the music.

One can stop the resonances of the speaker box walls completely but only at a very high cost. Box walls with appropriate reinforcements to brace themselves is sufficient in most cases. Extra support for the from baffle can be achieved by using thicker material here than the other walls.

In fig. 1 different kinds of internal bracing is shown. This internal bracing is required whenever large box volumes are to be utilised. The price for the external speaker cabinet material often plays substantial role. The difference in prices between different material thickness' can be enormous. With internal bracing one achieves the same goal more inexpensively than with an "oversized" wall thickness.

The internal bracing "A" should be used for support whenever an acoustic baffle is weakened by cut-outs. Bracing, shown at point "C", helps prevent large, wide walls from flexing. The board "C" should be a minimum of three time the width of the thickness of the wall on which it is attached.

The internal bracing "B" joins the speaker cabinet walls which are then closely joined together. It also divides up the larger sections of cabinet walls into small sections, thereby resonances are shifted to a higher frequency. It should never be attached exactly in the centre of the housing.

We also have available a range of other parts required to build speakers, such as crossover coils, capacitors etc.
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