CONSTRAINED LAYER ENCLOSURE CONSTRUCTION

All SP Technology Precision Monitoring products employ principles of advanced aerospace design to minimize enclosure wall vibration. Transient energy from the woofer that occurs from reproducing fast rising signals as well as back wave energy trapped inside the enclosure can induce the cabinet walls to resonate at certain frequencies. This panel vibration can be very high level and at very narrow frequency bands making them extremely difficult to eliminate. It has been shown that at certain frequencies sound can emanate from a panel at a level that is actually louder than the sound coming from the drivers. This phenomenon is due to the physics of resonance and is beyond the scope of this text to explain.

It is for this reason many high end manufacturers go to extremes in using expensive materials and complex methods in an attempt to eliminate the problem. Heavy bracing and excessively heavy and/or rigid materials have all been employed by many. One of the most often overused and fundamentally limited methods is the use of excessively rigid materials. The purpose, of course, is to make the enclosure less sensitive to vibration. Very heavy and/or expensive panel materials, often complex composites, concrete and even machined blocks of solid aluminum have all been used to achieve greater rigidity. While many of these techniques and materials do work, they all have one major drawback in common -- COST! This fact, along with over priced drive units, is the major causes of astronomically priced systems -- and are not really necessary. Superior engineering is the solution!

Advanced research and computer modeling in the field of vibration transmission has yielded very effective techniques to control unwanted mechanical resonance. Some of the first applications of this technology has been in the development of advanced aircraft. The upshot of this research has shown that a combination of rigidity and DAMPING produces superior results to "brute force" rigidity alone.

A relatively simple technique of alternately layering rigid materials with compliant "lossy" materials reduces vibration transmission with greater efficiency and lower material cost and complexity. Outer and inner layers of the more rigid material(s) are laminated to both surfaces of the compliant layers. Shearing forces that represent unwanted energy are produced at the boundaries between the dissimilar materials. These shearing forces are then converted to waste heat within the compliant membrane, thereby damping the unwanted vibration - simply, effectively and inexpensively.

Our Precision Monitoring products are constructed at all critical points with two layers of 3/4inch, Medium Density Fiberboard constraining an inner layer of "lossy" membrane. We also use large corner blocks at all panel joints. While this method may not have the allure and mystique of the exotic materials used by others...it doesn't incur the cost either. It does produce results rivaling costlier methods though. Time and again we have verified this fact with our own computer based accelerometer testing. You'll hear the difference and your wallet will thank us.