Topic: Hum with Shure SM57+Fireface UCX II
I'm recording speech with a Shure SM57 connected to my RME Fireface UCX II. At some point I noticed there is a slight hum. It is not loud at all, but if there is silence in the recording and you turn up the volume it is noticeable. Looking at a spectrogram, the hum is around 50 Hz so I wonder whether it might just be a ground loop. I only observe the hum when recording the microphone, but not when playing back music.
I have unplugged all unneeded electronics, I have even disconnected the USB cable of the interface, I have tried with a different SM57, a different interface, and a different cable, but some hum was always audible.
Any idea why this might be the case and how to get rid of it? My understanding is that dynamic microphones always exhibit a bit of a hiss, but no hum.