Canon C100 & multiple audio issues
My company has been struggling with multiple audio issues on 2 Canon EOS C100 (mark one) cameras. Camera A has the Dual Pixel Auto Focus update and is running firmware 22.214.171.124.00. Camera B does not have the autofocus update and has firmware 126.96.36.199.00 installed.
Here is a
illustrating the different noise issues. The camera’s have 3 audio issues listed bellow:
1. Unknown distortion on XLR input channel 1 when an external mic is attached (in the top handle grip unit). Sounds like overload, over modulation, clipping (but the audio levels are within good range).
2. When either input is switched to Mic +48 phantom power, there is a constant buzz accompanied by a high-rpm “beating or thumping" sound. The noise only appears when +48 is selected and is heard even when nothing is connected to the XLR inputs.
3. XLR input Chanel 1 presents a “white noise/hiss” sound similar to the common noises produced by a cameras internal mechanisms, only louder. Assuming it is camera noise, it is also present in Channel 2 at a lower level.
Cameras were purchased in late 2014 or early 2015.
3 different XLR cables used: 6’ low noise balanced *with polarity reversed, 25’ balanced Kopul 3000 Noiseless, 18” balanced Kopul 3000 Noiseless.
There is NO DISTORTION when the Shure SM87A mic is connected to Channel 1 with any of the XLR cables, (+48V was turned on in the camera). The +48V buzz and the white noise is still present.
We need to fix the C100 mic inputs and we also need to figure out what is causing these problems. My understanding of audio signals and electronic circuits is pretty basic but after researching the issues, it seems like there are a combination of possible factors. It seems likely that components inside the preamps in both cameras have become damaged over time. Could this be a result of frequently plugging in powered microphones into the XLR terminal when phantom power was active, or by a combination of activity like misfired cables? AND/OR the usage of the Sony ECM microphones over time possibly reversed the polarity of the C100’s preamps? The Shure SM87A did not present the Channel 1 distortion. I know that most microphones guard against unbalanced cables, etc., but many Shure mic’s add additional protection against voltage fluctuations, reverse voltage, and misswired cables/equipment through a variety of protection diodes and decoupling capacitors that aren’t included in other microphones. The Sony mic’s are wired with their copper shielding split between pin 1 and chassis ground, whereas the XLR cables are only wired to pin 1. Not sure if this has any relevance.
If anyone has suggestions or possible solutions let me know.
I'd send one in for repair, see what they find. Mine with similar setup do not exhibet this. Canon's repair folks are pretty good and turn around quickly.
Thanks Al. I've heard that about Canon service. We'll be sending them in next week.