Based on the S4s and S4b speakers. the S4i has been designed to work as LCR or Surround. With the design for inwall applications. Shallow 4” mounting depth and integral aluminum extrusion rear enclosure insure consistent performance and minimal sound propagation to adjacent rooms. Featuring our proprietary DPC-Array controlling Mid/High frequencies, centered by our finest 28mm Beryllium dome and dual 28mm TPCD ultra-lightweight domes. All transducers are developed ground up by our engineers – bringing decades of research, culminating in this world class design. We teamed up with companies in the USA and Sweden to bring modern material science to hi-fi. Utilizing advanced Comsol acoustic modeling, our DPC-array is the result of 18 months of painstaking simulations and prototyping. The result is one of the most technologically advanced loudspeakers available. This new tweeter/waveguide DPC-Array delivers amazing accuracy, smoothness, and directivity control to handle the critical vocal range and delicate treble. All S-Series speakers share the same DPC-Array and benefit from our unique timbre matching technique across the entire series. Another PERLISTEN inwall loudspeaker to be certified for THX Dominus