Serrano, there you go:
- Is it correct that pins R4 and R5 are on the same pin of the opamp. That’s pin 3. One of them is connected to VCC and the other to GND? Yes, this is know as voltage divider. At pin 3 we have 2v5.
- black wire of the electret microphone is connected to VCC. Shouldn’t that be on the VCC? Oops. Sorry. It has already been corrected. See Eagle added Shematic .
- It would help if you can list which pins go to which. Yeah, that’s why I put Eagle shematic for your and others conveniente.
- Thank you for feedback!