CABINET SHAPES
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SPEAKER CABINET LAMINATE / VENEER
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| No matter how good your speakers sound, if they don't look good no one will appreciate them but you. Applying this high-quality vinyl speaker wrap is a cost and time-effective way to achieve professional-looking results.
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Modern analysis seems to suggest that special cabinet dimension ratios do not have as much of an effect on performance as what was once assumed. Standing waves are caused by the reflection of frequency wavelengths that happen to be the same size as the distance between parallel surfaces, or surfaces that are at right angles to the first surface and of the same size. This effect can be minimized by using enclosure designs with non-parallel panels, or using proportions that can reduce the opportunities for the offending frequencies to reinforce themselves. The generally accepted "golden ratio" for these proportions is said to be 2.6/1.6/1, but the use of this ratio is not critically important when designing and building subwoofers. An airtight box, well braced, and adequately stuffed with damping material, will be as important as the shape of the enclosure. A free standing subwoofer enclosure must by necessity complement the environment in which it is used, so end table or coffee table shapes are common. Even built in subs face constraints imposed on them by the structure into which they are built.
CABINET MATERIALS AND CONSTRUCTION TECHNIQUES
The material of choice for subwoofer enclosures is MDF or medium density fiberboard. It has greater mass and density than particle board, which comes in second due to the use of larger particles or flakes of wood in its composition and lower glue content. Void free birch plywood is more appropriate for portable speakers because it is stronger and lighter than composition products, but unfortunately is not as dense. An airtight enclosure with well braced and damped panels will ensure that more sound energy reaches the listener instead of simply vibrating the cabinet walls or pushing the air out of small gaps. The use of a silicone or latex caulk should be used for all cabinet joints and even input terminals, no matter how solid things seem to be. Speaker sealing caulk or foam tape are convenient products that can ensure that the driver's mounting will not contribute to leaks. Special care should also be given to the grill cloth or screen that many users install to prevent the exposure of the driver to dust or foreign objects (or the probing fingers of inquisitive small children). The excursion limits of the subwoofer can be quite considerable and could exceed the clearances provided by some methods of protection, resulting in buzzes, rattles, or even damage to the driver.
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SUBWOOFER CABINET SPIKES
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| By rigidly coupling a loudspeaker enclosure to a floor by means of a "spiking" system, it is possible to dramatically improve clarity, stereo imaging and bass response. This is very apparent with subwoofer systems.
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The finishing of the enclosure is as important to some users as the actual acoustical performance of the subwoofer system. Popular finishes include genuine wood veneer, simulated wood laminates, paint, carpet, even spray on truck bed liner. Each has its own advantages and disadvantages, but it is probably one of the most subjective decisions that will be made during the whole subwoofer project. The one that you like the most or feel most comfortable applying is the best one for your project, as exterior finish will have little noticeable effect on subwoofer system performance.
What will have a serious effect on performance is stuffing. Stuffing, or filling, is used primarily to absorb or minimize standing wave reflections within the box. The proper use of stuffing can also affect the virtual box size that the subwoofer "sees" and can provide an increase in effective volume of 25% or more. This can be useful for applications where the enclosure size is marginally smaller than optimum, or to make up for internal volume losses from driver or brace displacements. Fiberglass, Dacron, Acousta-Stuf, acoustic foam, and long fiber wool are all popular and readily available acoustic damping materials. Be sure to identify the basic stuffing requirements or recommendations for your chosen project, but consider those to be a suggested starting point. Experimentation can lead to an amount of filling somewhat greater or smaller than originally specified, but can result in performance that satisfies the user's personal requirements.
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