The Microphone Amplifier is shown below and I should comment that perhaps more time was spent on this circuit simulation than perhaps any other element. I have a collection of vintage microphones including several Astatic D-104 Lollipop style microphones. There is something really cool about using a vintage microphone, whose design is perhaps 80 to 90 years old, with a very modern technology rig.

But the SDR Police on 40 Meters using their kilobuck rigs always delight in telling you that you are 10 Hz low (or as happened the other day I was told I was 8 Hz off frequency) and that your audio lacks lows. These older microphones do tend to favor the higher frequencies so necessary to bust DX pileups. Thus I evaluated how to improve the low frequency response of a single 2N3904 transistor microphone amp when used with the vintage microphones.

Mind you that a specfic microphone itself may not have the low frequency response; but for one's that do, the circuit will really make them shine. Thus the lengthy simulation time -- but the results were worth the effort. The plot shows the gain is flat over the audio range. You might try simulating some of the currently popular microphone amp stages and see how they stack up to this design.