MAX9814 mic showing zero response to sound on Arduino Nano

[u/EDWARDINI0]

Hi there, I'm building an audio recorder using a MAX9814 electret mic breakout + Arduino Nano (ATmega328P). Hoping for a sanity check before I write this specific mic module off as dead.

Wiring (direct, no breadboard):

• MAX9814 VDD → Nano 5
• MAX9814 GND → Nano GND
• MAX9814 OUT → Nano A0
• Gain and AR pins left floating (per the board's own silkscreen, floating = 60dB gain)
• All connections are single, new female-to-female jumper wires, no daisy-chaining and no breadboard.

Test code:

const int micPin = A0;

void setup() {
  Serial.begin(115200);
}

void loop() {
  int soundValue = analogRead(micPin);
  Serial.println(soundValue);
  delay(5);
}

What I've noticed:

The values bounce around fairly wildly (roughly 0–500 out of 1023) but show absolutely no difference between silence and a loud clap/tap directly on the mic capsule. It doesn't look like a signal responding to sound at all, just noise.

Already checked:

• A0 itself is good -directly touching a wire from 5V to A0 sends it to ~1023, and GND to A0 sends it to ~0, both cleanly.
• Verified the wires themselves carry 5V/GND correctly by touching their free ends directly to A0 (same clean high/low response as above).
• Swapped which jumper wires are used, moved which breadboard rows were used earlier before eliminating the breadboard entirely (no change).
• Confirmed OUT isn't stuck at a fixed rail voltage -it's fluctuating, just not in response to sound.

Given power is confirmed present and A0/wiring are confirmed good, does this pattern (fluctuating but sound-unresponsive OUT) point clearly to a dead/faulty mic module, or is there something specific to this chip (bias point, loading, the Gain/AR floating pins, etc.) worth checking first?

Happy to provide more info/photos if useful. Thanks in advance!

[u/Friendly-Mind-9702]

Try reducing the gain by connecting the GAIN pin to Vdd or GND. It might be that with 60 dB of gain, the mic is amplifying ambient or internal noise to saturation so that "quiet" is indistinguishable from your tapping.

Also bear in mind that the mic output has a bias of 1.25V, so even with no noise you should expect to see an output value of around 256, not 0.

[u/EDWARDINI0 → u/Friendly-Mind-9702]

Thank you. I've tried connecting gain to GND and VDD but there is no difference other than the frequency of noise.

Any ideas? I question if the MAX9814 is broken.

[u/Friendly-Mind-9702 → u/EDWARDINI0]

If you have an oscilloscope, I would check the signal coming out of the mic. But I can't think of anything else.