I am trying to analyze the following differential amplifier circuit and am wondering how to calculate overall gain (it will be fed with two copies of the same audio waveform 180 degrees out of phase with one another):
But the modifications in order to add filters to remove high frequencies makes the circuit I am working with more difficult to analyze. For example does R53 count as a feedback resistor and an input resistor at the same time? It's in both the feedback path and the input path. Does R54 factor into the voltage divider before the non-inverting input? Please advise.
I am working with AC signals in the audible range, from 20hZ to 20kHZ. For the purposes of this analysis I am not overly concerned about the frequency response of the filters, I want a general gain coefficient I can calculate for the passband. Thanks!