SC-424 is four-way, selectable tri/quad-amplified screen channel loudspeaker system comprised of two main units MHV-1090 mid-high very high-frequency system and LF-4215 low-frequency system. MHV-1090 mid-high-very high system features a high output, horn loaded 10-inch midrange cone driver and a coaxial neodymium high-frequency/very high-frequency compression driver . The MHV-1090 includes a driver protection network and a passive crossover for tri-amp operation. The protection circuitry prevents low-frequency signals from damaging the high-frequency and very high-frequency driver. A high power 10-inch cone driver allows operation as low as 250Hz and the advanced phase plug coupling permits a crossover point of up to 1800Hz to the high-frequency horn. This ensures that most of the dialog range is reproduced by a single element, for unmatched intelligibility. The coaxial neodymium high-frequency/very high frequency compression driver provides a dramatic improvement in dynamic response, clarity and transparency. The annular high-frequency diaphragm covers the frequency range between 1800 and 7000Hz with a smooth, linear response. The large diaphragm excursion of +/-0.8mm results in high output and increased power handling. The very high frequency driver covers the frequency range from 7000 to 22000Hz and eliminates the dome break up of conventional drivers that can cause resonance and harsh, metallic sound. The LF-4215 dual 15-inch (381mm) low-frequency enclosure is designed specifically to address the extended low-frequency response required for cinema applications. The LF-4215 covers the frequency range from 35 to 250Hz. Close coupled woofers (CCW), with their tight spacing between woofers, improves coupling and keeps coverage angles wide over a greater frequency range than more widely spaced designs. The LF-4215-8 is the 8 ohms version of the LF-4215. The SC-424 is designed for ease of installation. The MHV-1090 components come pre-assembled to reduce field assembly time. Three bolts are all that are required to secure the MHV-1090 to the top of the LF-4215 enclosure.