Possibly a ground loop?
You can purchase a ground loop lifter for less than ten euro online.
Even if this isn't the issue I personally think they are a handy tool to have in the box come the day you are recording somewhere with a grounding issue.
It sounds like 60-cycle hum. Check that the power source you are using to power the phantom power unit is grounded properly. Try different outlets in your house as well. While it's all hooked up try moving cables around to see if there is a change in the sound of the hum. That could indicate poor shielding on the cables. Move the mic itself away form the ...
Michael Hansen Buur pretty much answered this question in his comment, or at least gave a shove in the right direction.
But having the tools is only a small part of successful noise removal. There are many different ways a noisy recording can be improved and only knowledge, practice and experience can tell you which to use and how to use it effectively.
Sounds like you could benefit from a pre-amp of some sort to between the microphone and your camera. Your camera most likely takes a line level signal into the Aux jack. Here is an example of one way to handle your issue: The Saramonic SR-AX107 It will take the microphone and provide enough gain to get the signal up to line level. I can't vouch for the ...
What type of cables are you using to connect your audio interface into your camera? Does it support TRS? TRS cables generally do a great job of eliminating noise. The issue could range from gain staging (input on camera is too high), cable selection or it could be that the camera itself has a high self noise ratio.
Certain cell phone technology can cause this, it's a well documented issue, so searching on Google should provide more in-depth answers.
Turn your mobile off completely and leave outside the studio.
See if you still experience the noise.
Depending on how loud it is, this could just be normal. My Genelec speakers do the same, but it is only very low, so you need to be fairly close to really hear it. It is because they are active.
Is the hiss you hear much louder than that? Does it actually affect monitoring? If so you may have something faulty, but I expect this is normal behavior. I've ...
It's highly possible the tone wasn't detectable on the stage if it was large enough to be running an X-Curve. And thus if the film wasn't re-mixed for DVD/BluRay as they normally are, it's possible that tone which was always present is now audible in a near-field/mid-field home theater environment. Don't know this for a fact, could be a possibility though.
Whenever you use noise reduction you will always introduce some measure of digital artifacts. And you should be especially wary at the higher sample rates, because once you drop your sounds down a few octaves you will likely notice it more.
I think your best approach is to stave off the problem at its root, which is the preamp. Try positioning your mic ...
Izotope RX does work at native sample rates. I've been known to address some obv problems that are outside my hearing range just by visually identifing them.
alternatively just wait until you hear a sound in a downpitched context before de-noising it.
I'm not sure if you've found a solution to this problem yet, but even I deal with this same problem with the same gear and at the moment unable to afford new preamps or a good noise-removal software like Izotope RX. One thing I guess I have to do to get the best sound (if EQ isn't an option) is to use Audacity's noise-removal, I was surprised at how well it ...