Abstract: A loud speaker system comprising a first and a second main driver connected to common signal input terminals through crossover network means designed so as to pass signals of frequencies lower than a predetermined crossover frequency to said first driver and signals of frequencies higher than said crossover frequency to the said second driver, while in a crossover frequency range the signals are passed to both drivers with an amplitude which for increasing frequencies is decreasing for said first driver and increasing for said second driver in such a manner that the transfer function of the loud speaker system is approximated to a constant function inside and outside said crossover frequency range, and further comprising an auxiliary driver designed to work in said crossover frequency range and fed through filter means so as to have a transfer function which is substantially complementary of the deviation of the combined transfer function of the two main drivers from the constant function outside the crossove