OPA in mic preamp

[ussus]

I want to say that my circuit is starting to generate unwanted creaks and cracks. It is not noise.
How to say if the amplifier starts to oscillating and gives unwanted signal?
It is not feedback by the mic, it is produced by the amplifier itself.

Audioguru, I know these formulas for filters but in my opinion coupling capacitors are not the source of my problem.

 

[Audioguru]

Is your dual opamp an RC5532 or something else? Did you try another RC5532? Did you try another audio dual opamp? Did you build the circuit on a solderless breadboard that has intermittent contacts? tryt soldering everything together on a pcb or a compact stripboard layout.

Your input capacitor has the very high value of 1uF then it might be a polarized electrolytic type. Then maybe its polarity is backwards. That is why I almost always use a non-polarized film capacitor to couple audio signals. My resistor values are fairly high and I calculate a 20Hz cutoff so that reasonably small value film capacitors can be used. Your feedback resistor values are 10k, I would use 100k. Then I would use a 220nF film capacitor for C3 (7Hz cutoff frequency).

 

[Audioguru]

I typed my last reply then copied it and went back to page 1 to see the schematic. My copied text "took over and replaced" my reply that I posted yesterday so that reply and its attached schematic is now gone. Weird.