I recently sat down with a Hitler Youth survivor of the war and had her tell her story on camera. I was using a high quality lav mic running to Channel 1. The 48V phantom power was turned on for the mic and I believe Channel 1 was set to around -28 db. There was a significant amount of static in the headphones, but the audio was clear behind it. The static didn't show up on the levels on the monitor, and her voice levels were set well so they wouldn't peak. So I STUPIDLY assumed that it was just the headphones and it would be fine. All the other settings I tried weren't working. Of course I was way behind and running out of time to do the interview.
So now I have to redo the interview because what I was hearing in the headphones was, in fact, what I was capturing- stupid me.
When I did b-roll of a number of photo albums she had I unplugged the XLR from Channel 1. The same level of static showed up in these clips as well.
Lesson learned- testing exact equipment. But I didn't have this problem when I used a different mic (phantom powered) and was unaware of the problem with the phantom power with most mics.
Solution: don't use the camera's phantom power with this build.