Noisy audio from EOS C70?

[TarsierSpectral]

I'm trying to figure out if my C70 has faulty preamp or this is a normal noise level. I'm attaching a file.

Some info:
1. Firmware 1.1.3.1 (latest)
2. No mic attached
3. vol level set to 5, Manual
4. audio input selection set to INPUT TERMINALS Input1 MIC+48 for both channels.
5. No fan running while recording
6. When I drop my file into video editing timeline, I have an audio track that is just noise and I have to either delete it or lower the volume on that track. I can't verify it but I feel like I never had to do that in the past. 

Here is the file, if anyone is able to listen to it and tell me if this is a normal noise level on C70 I would greatly appreciate it.
https://www.dropbox.com/scl/fi/rqhdtp6kiw6vqb6zuht5g/5-MVI_0001.MP4?rlkey=9kogi48zoiuifzcx11rkb9sj1&...
https://www.dropbox.com/scl/fi/rqhdt...11rkb9sj1&dl=0

[Hazel_T]

Hi TarsierSpectral,

I'm sorry to hear you are getting noisy audio from the built in microphone on your EOS C70. For security reasons we are not able to access files from places like Dropbox through Canon support, so I'm unable to hear your audio example. There are a few things with the built in microphone.

One is that it is an omnidirectional microphone, so it does pick up every sound around it. That does tend to cause audio recorded with the built in microphone to be more messy than audio recorded with a different microphone. The other thing is that I see you have Mic+48v selected. That option adds more power to the microphone because it is for supplying phantom power to an attached microphone. If you are only using the built in microphone it is better to just select the Mic option. With that option the camera isn't adding extra power to the microphone, so it can clean up some static from the recorded audio from the built in microphone.

[TarsierSpectral]

Hi Hazel,

This is not from a built-in mic. As stated, there is no mic attached and the input is set to INPUT TERMINALS Input1 MIC+48 for both channels.

Without listening to my files, how can you determine if there is an issue?

[tgm]

Your initial post was a bit confusing as you seem talk about the XLR inputs, but you also indicate that the fan was not on (how would that matter to an input wihtout a microphone?).

The thing is: You can't test preamp noise from the XLR inputs without attaching a microphone. Without anything plugged in the circuit is open and it can produce all kinds of noise. That's normal. If you want to compare noise levels you would have to plug in a XLR adapter with a 150 ohm resistor to mimic a microphone load without actually recording a microphone capsule. See: 
https://www.youtube.com/watch?v=2DXEBahqBz4

Or, to make it more practical: When you have a usual microphone attached, let's say a shotgun mic, and you talk into it - can you hear any noise level (apart from room noise)?

[TarsierSpectral]

Sorry about the confusion. The reason I said the fan was not on is because that's one of the things people have been asking me on other forums, which I agree doesn't make sense. I wanted to state that from the beginning here, so no one suggests that maybe my fan is on. 
With the microphone attached the noise is amplified, because obviously it's picking up room noise. How can I differentiate room's noise from other noise? Both sound the same to me. It's just constant "SHHHHHHH". I don't have XLR adapter with a 150 ohm resistor. 

[shadowsports]

Greetings,

Can you provide a little backstory on your gear please.  Is this a new issue?  When did it start.  What proceeded his behavior?

[tgm]

You can't differentiate room's noise from preamp noise unless you do the test with the 150 Ohm dummy plug. 
What you can do with the unplugged XLRs:

1) Make sure channel 1 and 2 record separately - Audio menu page 1 "CH2 Input = INPUT 2", "ALC LINK = Separated"

2) Set the gain knobs to the exact same setting.

3) Record for a moment.

4) Import the recording in your NLE. 

Now compare audio channel 1 and 2. Noise should be more or less identical. If one channel is dramatically different to the other there might be a fault with the preamp. If they show same noise behaviour, there should be no issue.