# Audio Amplifier Circuit using op-amp [closed]

I am designing a circuit to amplify audio from microphone as well as removing dc offset from biasing the microphone. I searched for circuits available online for my personal project. I came across circuit from Sparkfun. I understood everything except the capacitor and resistor connected to non-inverting terminal of op-amp. Please explain the use of the capacitor C2 in the above schematic and why it is connected with the resistors R2 and R3.

Also, I am going to convert the analog signal after amplification to digital form using ADC. I want suggestion on bit resolution for audio applications that will provide acceptable voice quality during recreation of the voice.

Here is the schematic from the Sparkfun web site shared under the Creative Commons license.

## closed as off-topic by Marcus Müller, Dmitry Grigoryev, Voltage Spike, ThreePhaseEel, Daniel GrilloJan 16 '17 at 19:59

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• Without knowing the power supply voltages, suggesting an ADC is guesswork. Apart from that, shopping questions are off-topic because relevant answers become out of date. I think you could do some research on google about bit resolution for voice systems. Not enough effort shown in this question to solve it hence VTC. – Andy aka Sep 3 '16 at 11:16
• I'm voting to close this question as off-topic because of several factors listed above. – Andy aka Sep 3 '16 at 11:16
• Go find a tutorial on op-amps – Voltage Spike Jan 16 '17 at 17:05