This attenuator is fine. Adjust the value of the 27k resistor for the correct level without any distortion.- I used 1st attenuator to attenuate the audio signal of cell phone's Audio (R Gnd) to feed the Mic in of PC. Hoping that audio level on earphone speaker will not be attenuated (?). Resistors' values are just guessed![]()
1) You need a coupling capacitor between the grounded attenuator and the biased mic.- I am confused on 2nd attenuator because I have to attenuate ONLY the signal of 'Line out' of PC to feed the 'Mic in' of cell phone. But If I simply added an attenuator then the attenuator ALSO attenuates the signal of electret Mic of earphone and it is not good I think. Then how to add attenuator here?
2) The attenuator resistor values must be high enough so they do not attenuate the mic. Try 270k feeding 10k to ground or 470k feeding 47k to ground.
R3 is not needed.