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Canon C100 500hz audio hum

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Brad Allgood
Canon C100 500hz audio hum
on Apr 27, 2017 at 9:51:53 pm

Hi internet - Here's the deal. I have a Canon C100 with the latest firmware, but have been having audio issues with the camera. There is a fairly regular 500 hz hum in the camera audio. What can cause this in the Canon C100?

Here is the analysis done:
1. The hum is present on both channels.
2. The hum is present on both channels with or without a shotgun microphone attached.
3. The hum is more pronounced when a shotgun microphone is attached, and remains present regardless of using battery in microphone, or phantom power.
4. Multiple microphones have been tested, as well as handle attachments from different cameras. They do not get rid of the hum.
5. It seems like the hum is internal to the camera, and not a function of microphone attachment, cables, or even the handle for the C100.
6. The hum is not always present, however - perhaps there is interference when the camera heats up and the fan turns on? Can the fan internally cause the interference?

Has anyone experienced this issue? I know the frequency can be removed in audio post but that's just not really an acceptable option. Fix it in post is an irresponsible attitude.


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Todd Terry
Re: Canon C100 500hz audio hum
on Apr 27, 2017 at 10:34:33 pm

That is mysterious. Any time that I've experienced a hum in my Canon (C300 PL) we've been able to trace the issue, which was invariably a mic cable... either the cable itself was bad, had a bad connector, or was picking up interference from something else... such as the mic cable was crossing a power line, or was too close to an HMI ballast, or something like that. It sounds like you have eliminated all of those as a trouble source.

It's probably not the answer you want, but it sounds to me like you have done all you can do on your end, and the source of the trouble doesn't lie with any "operator error" or anything like that. Sadly, I believe it is "Send it back to Canon" time for repair.

I think your speculation about the fan is a valid one, since the problem seems to come and go. I don't know of any other electronic voodoo going on with the camera that is sometimes on and sometimes off, other than the fan (although I believe with my C300 that the fan automatically goes off when you roll... it seems that way to me). But being that the fan is a mechanical thing with a motor it would seem logical that it turning on and off could cause some sort of interference, maybe an internal connection to it is loose or something.

Yes that does sound like something that is fixable in post, but you are right in that you don't want to have to do that, nor is that the best route. Getting it fixed right is the best option. Fortunately I have always found Canon repair to be quite good and pretty speedy.

Good luck!

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Brad Allgood
Re: Canon C100 500hz audio hum
on Apr 29, 2017 at 7:42:26 pm

Here is a spectral analysis of the hum I'm referring to. It seems to increase in frequency as the camera runs for longer, say during the same clip.


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Todd Terry
Re: Canon C100 500hz audio hum
on Apr 29, 2017 at 8:23:56 pm

Sadly, that means nothing to me.

You might ask over in the Audio Pros forum where they have more knowledge in that realm, and there's much more traffic than in this one as well (sadly we get almost no traffic in here in the Canon Forum anymore.... which I choose to see as a glass-is-half-full kind of thing, meaning Canon users are not having many problems these days).

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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