I have seen a few different ways of adding DC bias to an audio signal. I have simulated them and they all give me similar results, but I cant Figure out is why choose A over B or C. My audio source will be a Line Level Audio -2V to +2V AC passed through a 220uF coupling cap and then a low pass filter(RC, 2 pole). edit -The signal will be read by an ADC
First way is using a Voltage divider, Simple Biasing Circuit
This is pretty self explanatory and i understand how it work. I have also seen this same design using Diode but could not find the example.
Next example - How to read an audio signal using ATMega328? - picture is from endolith's answer.
another one that i have seen is I don't quite understand this FET-BJT preamp circuit And the schematic is for a pre-amp, and there are 2 versions and both add a bias.
My question is what is the best practice for adding the bias to an audio signal? what are some of the other ways to add a DC bias to the signal?
Edit/update Looking at the answers - using the second one looks like it will work best for my application, using something like this- is there any other improvements I can make? other then Stable Vref/power rails.