Artekit AK-MAX9814

The AK-MAX9814 is a board with a microphone and a high-gain amplifier with AGC.


Introduction

The Artekit AK-MAX9814 is a board with an electret microphone coupled to a high gain amplifier (the Maxim MAX9814) capable of gaining 40dB, 50dB and 60dB.

The MAX9814 also has Automatic Gain Control (AGC) to avoid saturation when the board is placed close to the audio source.

The AK-MAX9814 breakout board does not require any programming: it only requires a power supply between 2.7V - 5.5V. You can optionally adjust the gain level using just the GAIN pin or the Attack/Release ratio using the A/R pin.

Artekit Labs AK-MAX9814 board.

AK-MAX9814 characteristics

  • High gain - 40dB, 50dB and 60dB.
  • 2.7V to 5.5V typical power supply.
  • Dedicated pin for gain selection.
  • Dedicated pin for Attack/Release ratio selections.
  • Audio output max 2Vpp.
  • Low power consumption (3mA).
  • 100Hz to 20KHz frequency response.

Microphone characteristics

  • Sensitivity: -42±3dB (0dB=1V/Pa.1KHz).
  • Output Impedance: 2.2KΩ.
  • Frequency Range: 100-20KHz.
  • Current Consumption: 0.5mA (Max).
  • Signal/Noise Ratio: ≥58dB.
  • Sound Pressure Level: 110dB.

Applications

  • Due to its high sensibility, the board is the ideal choice for ambient audio sensing applications.
  • General purpose audio projets.

Hardware overview

The AK-MAX9814 basically breaks out the pins of the MAX9814 amplifier into 0.1” (2.54mm) spaced pins.

Artekit Labs AK-MAX9814 board. Top/bottom view.


Board pinout

Artekit Labs AK-MAX9814 board pinout description.

NAME TYPE DESCRIPTION
GND Ground Circuit ground
VCC Power Power supply. 2.7V to 5.5V.
GAIN Input Gain selection. More about this pin here below.
OUT Output Audio output (max 2Vpp). Blocked through a 4.7uF capacitor.
A/R Input Attack/Release selection. More about this pin here below.

GAIN pin

  • Leave this pin unconnected to set the gain to uncompressed 60dB.
  • Connect this pin to GND to set 50dB gain.
  • Connect this pin to VCC to set 40dB gain.

A/R pin (Attack-to-Release (A/R) control)

  • Leave this pin unconnected to set A/R to 1:4000.
  • Connect this pin to GND to set A/R to 1:500.
  • Connect this pin to VCC to set A/R to 1:2000.

Wiring and Testing

The AK-MAX9814 board is simple to use. This simple setup here below allows you to test all board features, like the different gain values and A/R settings.

AK-MAX9814 board wiring example.

The use of a battery in the example here above provides power to the board while avoiding all other electrical noise. And because the AK-MAX9814 board is mono, you must connect together the right channel with the left channel of your headphones into the OUT pin of the board.

Note: do not replace the headphones with speakers, because the output of the speakers will enter again into the microphone producing noise (known as Larsen effect).

Additional resources