Phonic iA231F dual 31-band 1/3 octave graphic equalizers allow users to easily and conveniently adjust the frequency response of their sound system to best suit their environment. Features include feedback detection, variable low and high cut filters, adjustable limiter, as well as a subwoofer output with its own crossover frequency control. Encompassing an array of useful features, the iA231F is the most necessary component to any live stage or studio setup.