Adafruit electret microphone with built in amplifier adafruit 1713 the adafruit electret microphone agc amplifiers feature a built in microphone and use the max9814 microphone amplifier the amplifiers automatic gain control will reduce loud sounds and amplify the quiet ones to minimise volume related distortion you can configure the maximum gain to 40 50 or 60db and the attackrelease ratio to 14000 12000 or 1500 via jumper settingsthe amplifiers output is approximately 2vpp with a