Avoiding Distortion When Recording a Piano
The piano is a powerful instrument and has a very wide dynamic range. When I measure my playing with a sound meter, the softest sound I make on the piano (Steinway model L) inside a closed room is 21dB, while the loudest being around 80dB. What this means is, even with the microphones positioned around one foot away from the soundboard, I still have to be very careful with the potential “distortion” during the recording.
Remember this old post in which I talked about how I set up my recording equipment? I wrote about how I set the microphone input level (mic gain) on the interface — “I test the sound level of my piano by playing the loudest chords I will be recording before the session starts. If the lights turn red, that means the recording input level is too high and may cause sound distortion in the recording. I adjust the input level down to make sure the lights stay green at the loudest sound.”
So exactly what does “distortion” sound like? In the following music sample, you will hear three sets of random chords. The first set is distorted (high input gain on the interface), and the second set is the desired sound (after lowering the input gain). The third set is also slightly distorted if you pay close attention to it. This set was recorded with the the correct input gain on the interface and the maximum input gain in the DAW. Be warned — this sample is LOUD and you may want to turn down your microphone or speaker before playing it.
From the sample, we can see that distortion can be caused by the high input gain on the interface or DAW, but once the setting is correct on the interface, the distortion won’t be as bad even when the setting in the DAW is off.
Distortion can also happen when the output level is set too high. Ever listened to music on crappy computer speakers and hear those “broken sounds” when the volume is turned up to the maximum?
In certain pop music, distortion may sometimes be used as a “special effect” during the music production process. However, it doesn’t work quite well in classical piano recordings, where clarity and beautiful timber are the most desirable.
When recording classical piano (especially the dramatic music from the Romantic period), we must keep a good balance — we not only need to ensure the loudest sound is not distorted, and the softest tones also need be clearly audible.