video still
LA-2A Leveling Amplifier
Teletronix
The LA-2A is a hand-wired, vacuum tube-based audio compressor developed by Teletronix and released commercially in 1962. It uses an electroluminescent panel and cadmium sulfide photoresistor for program-dependent gain reduction. Its attack is fixed at 10 ms; its release varies from 60 ms to 15 seconds depending on input. It preserves perceived performance dynamics under heavy compression. UREI acquired its patent rights in 1967.