Adafruit Electret Microphone Amplifier MAX9814

Add an ear to your project with this well-designed electret microphone amplifier with automatic gain control (AGC). This fully assembled and tested board comes with a 20-20KHz electret microphone soldered on. For amplification, we use the Maxim MAX9814, a specialty chip designed for amplifying electret microphones in situations where the loudness of the audio isn't predictable.

This microphone amplifier module is a step above the rest, featuring built-in automatic gain control. The AGC in the amplifier means that nearby loud sounds will be quieted so they don't overwhelm and clip the amplifier, while quiet, far-away sounds will be amplified. This amplifier is ideal for recording or detecting audio in settings where levels change, eliminating the need to constantly adjust the amplifier gain.

The chip at the heart of this amplifier is the MAX9814, which offers a few configurable options. The default maximum gain is 60dB, but it can be set to 40dB or 50dB by jumpering the Gain pin to VCC or ground. You can also change the attack/release ratio from the default 1:4000 to 1:2000 or 1:500. The output from the amplifier is about 2Vpp max on a 1.25V DC bias, making it compatible with any analog/digital converter that accepts up to 3.3V input. To connect it to a line input, simply use a 1uF blocking capacitor in series.

For audio-reactive projects, we suggest using an FFT driver library, which can take the audio input and translate it into frequencies.

Each order comes with one assembled and tested board, with the electret microphone pre-soldered on, and a small piece of header. Our tutorial will help you get started with using and testing the microphone amplifier.