Hey, I would like to ask what is the gain of mic signal set in ADC? I know the operating voltage of microphones and i know that the gain in ALSA is set to 0. Soo what is the gain beween mic and raspberry? Is it dependable on such kind of algorithm or is it set up on precise value?
Regards Wiktor
Hello @Wiktor, I am currently working on this same issue. Do you have any further knowledge about this?
Correct me if I’m wrong, the flow of signal is like this.
Signal -->–MIC–>>–AC108–>>–AC101–> Raspberry Pi
Based on the spec of AC101, it supports Automatic Gain Control (AGC) adjusting ADC reading output. Also, AGC can be used to maintain a constant recording level in the ADC record path.
Based on the spec of AC108, it has Programmable Gain Amplifier (PGA), which can adjust the gain from 0 to 30 dB.
Despite knowing these, I still have no idea how actually the gain is set, I’ll try looking into the driver: respeaker/sound-card on GitHub.