Heinrich's HML-10A Induction Loop Amplifier is an affordable amplifier that drives a wire loop installed in the ceiling or floor of a venue up to 600 meters per amplifier. This enables hearing-aid users in the area enclosed by the wire loop to hear announcements, soundtracks, or music. Hearing-aid users can set their devices to the T-mode setting to receive the signal coming from the loop for excellent audio quality announcements. The loop amplifier can be connected to a mixing amplifier's line-level output, or it can accept up to three microphone/line signals directly. A 100 V priority input is available for uplink to a voice alarm system. This input can be monitored for the presence of a pilot tone. The built-in supervision monitors all key functions of the loop amplifier, and the fault state is available on a fail-safe relay. The loop amplifier is fitted with a limiter to limit the output field strength to the prescribed 100 mA/m. This circuitry can also function as an Automatic Gain Control (AGC), so soft signals are boosted for clarity while loud signals are attenuated so that all information is presented at a comfortable listening level. Tone controls and a metal loss compensation circuit are available to adjust the sound to the program material and the environment. After installation, the controls can be locked to prevent unwanted access. Although one Loop Amplifier can cover up to 600m, the Loop Amplifier is stackable (master/slave configuration), to cover larger areas. It also supports low spill schemes. Its unique quadrate configuration provides uniform field strengths over multiple loops.