Frequency response is from 50 Hz to 20,000 Hz. Only a high-pass filter above 50 Hz, 24 dB/octave or higher is needed. If a very high SPL of low frequencies is required, it is recommended to couple sub woofers with the A9 Array. Recommended crossover point would be 80Hz –120Hz, high-pass filter with the slope of 24 dB/octave or higher.