The ST-GCA3 constantly adjusts for changes in input levels, bringing up low levels, and reducing gain for high levels. The audio level is constantly adjusted to maintain the correct output. The AGC adjustment rate is switch-selectable. Making audio levels uniform and consistent improves the performance of nearly any type of audio system, and the ST-GCA3 SLOW mode is ideal for leveling music sources. The FAST setting of the ST-GCA3 makes it ideal for use in systems prone to loud bursts of audio, and inconsistent levels which must be constantly and quickly corrected. In paging systems, intercom systems, and mic mixing applications where intelligibility is a must the ST-GCA3 FAST mode can be the key to optimum performance.