Polk Audio 620-RT (Ea) High Performance In-Ceiling Loudspeaker
Just like Matthew Polk's Signature Reference Theater (SRT) system, the components used in the RT Series benefit from Dynamic Balance, a technology which came out of a joint research project between Polk Audio and Johns Hopkins University. This laser imaging research enabled Polk to view on a microscopic level the entire vibrating surface of a driver or tweeter. By this method Polk was able to observe the resonances, which develop on speaker cones as they move. These resonances are the root cause of frequency response distortions.As an x-ray enables a physician to discover the root cause of a symptom and prescribe the right treatment for a cure, this laser imaging technique allowed Polk engineers to find the right combinations of high tech materials, geometry and construction techniques to tune out the offending resonances. The benefit of Dynamic Balance is the dramatic improvement in the sound quality of our speakers, which every listener can appreciate.  You no longer have to choose between excellent bass and smooth, clear midrange. Now you can have it all thanks to Dynamic Balance technology.A crossover is the part of the speaker system, which directs high frequencies to the tweeter and lower range frequencies to the woofer. But crossovers can create distortion, called phase shift, which reduces clarity and degrades the ability of the speaker to create a life-like spatial image. Thanks to Dynamic Balance technology, the response of Polk's mid-woofers remains accurate at much higher frequencies than conventional drivers. This allows Polk to place the crossover frequency above the range where your ear can most easily detect phase shirt (the critical midrange). The result is clarity and imaging so outstanding that the speakers seem to melt away. You'll feel as if you're at a live performance or actually on the movie set.And the result of all these technologies? One listen will tell you. You