Bellari RP562 Studio Tube Sonic Exciter XLR Inputs/ Outputs, Internal Power Supply The Bellari RP562 Stereo Tube Sonic Exciter. The RP562 Stereo Tube Sonic Exciter is a two channel frequency compensation device designed to add life and animation to your sound. The frequency range that a human ear can detect is roughly 20Hz to 20kHz. However, the frequency response a normal speaker can effectively reproduce is much, much less. Additionally, speakers add distortion and phase changes that make the sound different from that of the original material. A sonic exciter restores clarity and presence to the processed signal by correcting phase changes and harmonic structure differences. In other words, it puts the components of the sound back where they belong. Using a vacuum tube circuit in this configuration not only restores the clarity lost in previous processes, it adds warmth and a slightly compressed attribute to the program material. This addition to the sonic excitement process makes the final sound even larger, cleaner and clearer.