The key to recording any instrument in a live environment is being able to place the microphones in a position that captures the sound effectively and yet does not hinder the lines of sight of the audience. This is much easier to do if you understand the instrument that you are trying to record including its characteristics, physical workings and dynamic range.
The characteristics of a piano come from the harmonics and its percussive nature. Both of these are affected by the hardness and density of the felt on the hammers alongside the strength at which the string is struck. Smaller sized pianos tend to have a less pure sound quality due to the strength and size of the strings.
It is important to remember that with the dampers lifted pianos can resonate between 10 and 40 seconds and this varies according to the build quality of the instrument. With a grand piano this is further affected by the reflections according to the angle of the lid primarily affecting the middle and high-end frequencies. In a live environment many performers choose to close the lid of a grand piano creating a duller sound as the high-end frequencies cannot radiate fully and also decreasing the overall sound level (alongside causing a nightmare for microphone placement!). The alternative of removing the lid altogether also creates a similar problem although the amount of dullness is dependent on the proximity and reflective angle of the ceiling.
For a classical recording of a grand piano I feel that it is always best to have the lid raised so to create the reflective angle and allow all of the frequencies to resonate. The microphones of choice would be omni-directional condensers (e.g. Neumann U87’s). These would be placed in a space pair close to the piano at equidistance from the strings and the underside of the lid. As it is a live recording it is important that they are not placed too far from the instrument, as they would potentially pick up too much of the audience and not enough of the piano. It is important to remember to position the microphones and then listen back to the sound that is being received and adjust as necessary – the smallest movement in microphone placement can make the biggest difference in the sound that it is captured.
I would however place a pair of ambient room microphones that were also omni-directional condensers (e.g. AKG414’s) in a spaced pair formation to allow control over the amount of audience pick up and create a blend between the microphones to encompass both the piano and the audience.
