What are the relative merits of using inverting/non-inverting op-amp configurations for a microphone preamp? While searching for microphone preamp schematics based on op-amps, I have found both inverting, and non-inverting varieties.
You can have a non-inverting amplifier, which presents a massive input impedance to your microphone. The values of R1 and R2 do not alter the input impedance of the gain stage as far as I see.
You can also use an inverting amplifier, but here you have to make sure that the value of R1 is sufficiently high so as not to load the microphone (perhaps using the rule of thumb that the input impedance should be approximately 10x the nominal impedance of the microphone).
Aside from signal phase, are there any major differences in the outputs from these gain stages??
Best Answer
If you just want a simple flat gain including DC around ground, then about the only meaningful difference is that the non-inverting configuration has high input impedance and the inverting a controlled input impedance referenced to ground.
The differences matter more when you want to do other things, like bring the DC gain down to 1, not load a mid-supply reference, keep turnon fast, etc.