48V Phantom Powered Microphone Circuit - Discrete Component Version Prototype Available - 2023-08-22

I. Background
 
I saw a condenser microphone on Xianyu (a second-hand marketplace), described as having the shape of a Newman 103, quite compact, which hit my pain point. So I ordered it. After receiving it, I tried recording, but the AC hum was very loud, and there were also occasional crackling and irregular noises.
Upon disassembling it, I found the circuit was very simple, but the output was unbalanced, resulting in a large background noise, making it unusable. Fortunately, I had a 25mm large-diaphragm electret condenser microphone head on hand, so I decided to make a circuit board to replace the existing rudimentary board.
 
II. Reference Circuit
 
I had seen a circuit made by a netizen named "Superrealistic Silly Bird" on a forum, and I also saved it: https://oshwhub.com/Postidiot/opa-microphones.
 
However, his board couldn't be used in my microphone housing, so I redesigned it and made a PCB.
To be able to use both electret and pure condenser microphone heads, the circuit was slightly modified. If using an electret label, replace C1 with a wire and do not solder R1 (1G ohm resistor). This will give the electret label a 6V polarization voltage.
If using a capacitor label, its polarization voltage comes from a 48V phantom voltage in series with a 1K resistor. I haven't had the opportunity to test this, so I don't know if the circuit will work properly.
 
If you need to build one, please do not directly use the circuit's BOM, because the resistance values ​​of the resistors and other components are specified later, not looked up from a library, to ensure consistent resistor pad spacing (package).
 
A tutorial video is available on Bilibili for reference:
 
DIY Large Diaphragm Microphone
https://www.bilibili.com/video/BV1QP411a7Ls/?spm_id_from=333.999.0.0
 
I didn't take photos of the tutorial video, only a few screenshots from the video.