MAX9814 threshold

[memel182]

Hello,

I am using this board to record the ambiant sound in a room and/or environment sound outdoor. But playing back the recorded sound I found that in quiet moments (silence), I ear a lot of noise. I made some improvements in my circuitry to reduce it, but now I assume that I need to "weight" the values recorded in silence since they are the most amplified (hope I am clear enough).

But now I lack another information : is it possible to know the gain applied by the AGC at any time? I do not mean the static gain configured by the corresponding pin, but the automatic gain choosen by the AGC component...

I have read that it is possible to configure the threshold at what the AGC triggers : that's ok, and would let me know what sound is amplified or not, but not the exact gain...

Thanks for your help

[adafruit_support_bill]

I don't believe there is a way to read the applied gain from the AGC circuit. For your application, the MAX4466 may be a better choice.
https://www.adafruit.com/product/1063

[memel182]

Ok, I will try a different way... Is there any example schematic on how to set the threshold? (define the resistors values regarding the wanted threshold values...)

[adafruit_support_bill]

AGC does not increase gain for low signals. It reduces gain for signals above the threshold. So for 'quiet' times, the gain will be what you program it for.
You can disable AGC entirely by shorting the TH pin to MICBIAS. To set a specific threshold, you can change the values of R1 and R2. MICBIAS is 2v. The standard formula for a resistor divider is:

Vout = R2 / (R1 + R2) * Vin.