Mic saturation question

[scientistplayspiano]

I have basic knowledge about recording, have been using USB mics for a while.
Now I start to record with a pair of Rode M5 with Focusrite Scarlett 2i2 interface.

The sound quality is excellent, but it seems the mic got saturated easily at the loudest sound. I am recording a Steinway B grand piano in a small studio room. The sound is LOUD. I tried to adjust the gains both on interface and on computer, even trying to move mic a little further away (the space is really tight), but nothing seems to help much.

On the other hand, the cheap mic on my camera seems to work fine (not saturated). I am now curious, is it because the dynamic range of M5 is small, or I did something wrong?

[quantum]

Can you post a clip of the audio in question.  Can you describe your mic positioning in more detail (such as measurements from the piano).  Since you mentioned you were making adjustments in the computer, can you describe what things you did in your DAW.

According to the spec sheet, the Rode M5 have a dynamic range of 121 dB and a max SPL of 140 dB.  110 dB is generally considered the human pain threshold.  These mics are able to handle loud sounds. 

The cheap internal camera mics might have been set to auto gain, giving you the illusion that they can handle loud sounds. As well they may also be less sensitive.  However, most XLR mics, even entry level ones, will deliver a quality and performance far above the typical internal camera mic.  There is  a reason why people like to avoid using a camera's built in mics, especially so for music recording.

Getting better recording equipment also comes with the need to work a bit more to get a good sound.  They are not as simple as set-it-and-forget-it like internal camera mics.  Similar to upgrading to a better piano, you also need to learn playing techniques to take advantage of the better instrument.

Have a look at this video:

First make sure your input type is set to Mic Level (not instrument level or line level). 

Check the gain level for clipping.  On the piano, play the loudest passage of music you anticipate using.  A good starting point is to aim for a -6 dB for the loudest portion of music, or the yellow light as in the video above.  As you become more familiar with how your recording equipment, instrument and recording space work together, you can change this starting point.  Classical music is very dynamic, don't set your gain to the quiet parts of a piece, you want those to sound quiet.  The loud parts of the music are the concern with regard to clipping.

In your DAW, set the fader and gain to default.  Typically you don't need to play with these in the recording phase, they get used more in the post production stages.  Still, check the level meters in the DAW to make sure they are not clipping.  Clipping at the recording stage generally happens at the mic or preamp.  Clipping at the post production stage means you probably pushed a level too far in the DAW.

Observe the level meters when judging loudness, so you know the level being recorded to the file.  Also remember, that your headphone output is another source of volume control, one that does not affect the recorded sounds.

[scientistplayspiano]

Thank you for all the detailed information. I actually watched that video before!
Here is what confused me: the mic should be far from saturated level, I turn down the gain on the interface and in Audacity very low. However, when the performer delivers a strong chords on piano, that profile will show a plateau, although the peak value is far from the saturation level .

I attached a picture of the peak.

[quantum]

Well something is going on there.  What is the dB reading at the point where the wav is flattened?

Do a test if you can intentionally produce a clip where the level goes above 0 dB.  Turn up the gain, scream into the mic or make some obviously loud noises.  Does the level reach 0 dB and clip? 

Next steps would be to follow the audio signal path, and at every point check if there is clipping or limiting going on.  Check the knob lights on the 2i2, do they turn red when you record loud sounds?  You need to watch the lights as you record, don't just rely on examining the wav in Audacity because the issue might be happening before the signal reaches that point.

What operating system are you using?  I've experienced recent versions of Windows 10 making changes to the sound settings, usually related to an update.  In W10 go into System > Sound and double check everything is as you want.  Turn of all effects and sound enhancements.  Make sure the sample rate matches what the 2i2 is set to. 

Came across this report:
https://forum.audacityteam.org/viewtopic.php?t=101424

Try a driver reinstall for the 2i2.