At this point im convinced my fast track solo is not compatible with my NT1a be it broken in some way or not. It has caused this ringing sound with AT2020, and 2 NT1a mics. It didn't cause this problem with a behrigner b1 or cad m179. i can not afford another audio interface for a while im pretty much mentally ill so have hard time holding jobs. Will pay back. or return interface if it does not work with my mic.