[Q] Mic Volume too low on LG Optimus F6/D500 topic

When making a call, the volume is too low for anyone to hear me. However, as soon as I switch to speakerphone, it works fine. Recording seems to work fine as well. This makes me think there is something wrong with the bottom mic. It's stock T-Mobile ROM, I just rooted it, however, can't find an app that could adjust mic volume.

I've tried searching, but there are thousands of threads for Galaxy S2, that require you enter a secret menu. I couldn't find a code for my phone.