Problem with an electret microphone connect to esp32 with RJ9

Thread Starter


Joined Dec 13, 2021

Sorry for if the question if I'm not clear, i'm not nor développer, nor electronician , but i've done a small project with esp32 to do a full duplex audio stream, well done , but now I have a problem to connect the microphone i want to use without have too noise.

I want to use a old headset of phone in what i have an electret microphone and speaker with RJ9 wire (4 connector), one pair is for speaker, that work perfectly, and the other pair, is for the electret microphone CMA-4544-PFW, in the headset i have to connect to a max9814 near to my esp32 with an rj9 cable with speaker wire in the same. The module work perfectly when the microphone IS directly connect on the max9818, but when it is far and connect with the RJ9 where the two pairs of wire are in the same cable i have really too much noise. I know my problem is not really an electronic or developpement promblem, but i really dont know how to correct this audio connection problem, and i hope some of you know something that could help me .
I think as the headset was already connect with the same type of microphone to a telephone like this without noise problem even if the speaker is active, i suppose there is a method ( capacitor? Resistor ?) To make that possible...

I'm sorry that i can't share my code project nor the electronic schem, but actually, i don't know how to do as i said, it's the first Time i use a microcontroller board and first time i devellop something other that HTML/PHP things.

I prey for tour help .
Thanks, i promise toi share all that as soon as possible .

Audioguru again

Joined Oct 21, 2019
You did not describe the noise but if it transmits low frequency hum or buzz (from electricity wiring in walls) then the cable to the mic is not a shielded audio cable. The shield blocks hum and other interference. Ordinary wires to a mic act like an antenna to hum and other interference. All low level microphones are connected with shielded audio cables.