Recording a piano isn’t easy. The sound quality depends not just on the microphones, but on the condition of the piano and oftentimes the room where the piano is located. For the best results, keep your piano tuned and in good working order. Proper maintenance will eliminate one big hurdle of recording a piano. The rest is just a matter of good mic placement.
The piano is generally recorded using close mic’ing technique. Ideally, you’ll want a minimum of two microphones. Usually, the microphone capturing the higher strings is assigned to the left channel and the microphone capturing the lower strings is assigned to the right channel in the final stereo mix, though the stereo spread generally is not hard left and right. While a single microphone can be used, the lower and upper extremities of the instrument will likely be compromised. To capture the full range of sound, pick up a pair of instrument microphones, such as the MXL CR21 Pair or the MXL 603 Pair.