Troubleshooting camera hum when on ac power.
So, I have a very specific problem, that is also unfortunately hard to test out solutions, so I'm just trying to gather as many possible solutions as possible.
I work for an non-profit that puts on a conference in Europe each year, unfortunately, we're located in the US, hence the difficulty to test possible solutions.
We film hundreds of hours of footage each year with primarily cameras in the vixia line, two different models a few years old, but both with the same problem (similar to this https://www.bhphotovideo.com/c/product/1293612-REG/canon_0280c019_vixia_hf_...
The issue is, each year I spend more and more money on batteries that are fading fast. So the solution to this is to plug the camera into the wall with a simple plug adaptor for the European socket. This works fine until our mic set up comes into play. I haven't found a great mic with the mini jack, that works for our situation and that is also in our price range so we use an XLR lav, Shure SM11s, connected through an XLR to mini convertor.
When this mic is plugged in, and the camera is plugged into the wall, there is a terrible hum/buzz that makes the video unusable.
On my last trip I tested out some ferrite core cable clips thinking that this was one thing that was different from my few canon XA20s I have that can be plugged in without a problem. Unfortunately, that wasn't enough to solve the issue, but I did find out that if I held my finger on the metal ring around the lens, the humming stopped and was completely fine.
Apart from having people stand there and hold their finger on the camera the whole hour long session, I've been mulling over how to hack this so that we can plug in and I don't have throw so much money into updating batteries each year.
Not sure if anyone else has experienced this, but any ideas are extremely helpful, thanks!
Sounds like you have a grounding issue caused by dirty power sources in your European locations. Do the mics sound clean with using AC power in the US?
If so, the power is your culprit... and sadly, I don't know much way around it. Maybe some others with more electrical knowledge in here can help. My first suggestion when I started reading your post was to try ferrite cable cores.... but then sadly saw that you tried that with no luck.
You might have better luck using a different mic, a different XLR adapter, or even a different mic cable (and making sure your mic cable is not near any power adapters, or crosses a power line)... but I know that is hard or even impossible to test since you are not where the trouble is.
The fact that the humming stops when you touch the camera tells us that it is a grounding issue. I suppose you could rig up something where you run a physical ground wire from a grounded source and attach it somehow or figure a way to keep it touching the metal lens ring. Not a very elegant solution, but it would at least keep you from having to hold your finger in place.
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