The LA-2A's gain control scheme was revolutionary: Gain reduction was controlled by applying the audio voltage from a tube peak detector to an electroluminescent panel that glowed onto a light-sensitive, cadmium-sulfide resistor, with a second matched photoconductive cell controlling the metering section. With up to 40 dB of smooth gain limiting, flat 30 to 15,000Hz (±0.1dB) frequency response and low-noise performance, the LA-2A soon became a studio standard.