Recording piano can be one of the trickier things to get right in the studio. Different microphone positions and techniques can produce wildly different results, and the recording environment can have a large effect on the sound as well.
So my goal is always to keep things as simple as possible when it comes to recording a piano. Sticking to a few core techniques can help you capture solid recordings and record the take you want.
One of the reasons for the difficulty in recording piano is due to the sound being produced by the whole body of the instrument. Sound waves emerge from all over a piano, and different parts of the instrument's wooden body resonate at different frequencies. It makes the positioning of your microphones very important to get right.
There are two main types of acoustic piano:
A piano will go out of tune at some point, and the only way around it is to get a professional piano tuner to re-tune it. It goes without saying that if you want a quality recording, the piano has to be in tune.
Before recording begins, it's worth checking that the pianist's seat doesn't squeak or make any unwanted noises as it will be easily picked up by the microphones. Noise from the piano's pedals can also be an issue - WD-40 can usually sort this out though.
If you're unable to use a real piano in your own studio (and I'd predict that most home studio owners are in this position), or if your room acoustics cause too many issues, there are a couple of alternatives:
A high-quality ROMpler, such as Akoustik Piano from Native Instruments
As with any instrument, the microphones you use and where you place them can have a big impact on the recorded sound. A few things to keep in mind when you recording piano are:
Recording in mono with one mic or in stereo with two mics are both good options for recording piano. Recording in mono is definitely the easiest choice, but the sound can be narrow and a bit flat - it won't reflect the real way that we hear the instrument (in stereo), with the lower frequencies panned to one side and the higher frequencies panned to the other side.
Recording piano in stereo mirrors our real-world experience of listening to a piano, as it allows you to pan one mic to the left and one to the right - the amount of pan you use will control how wide the stereo image is. The mic used for the lower notes is usually panned to the left and the mic for higher notes panned to the right, reflecting how a pianist would hear the instrument when playing.
Home studios are usually restricted in the space available, which makes a piano perfect for close micing. It cuts down on unwanted ambience from the room, and you can then add reverb during mixing to help blend the piano with the other instruments in your production.
There are lots of different ways to record piano, and each technique will produce its own kind of tone. It's pretty unlikely that you'll have a grand piano as a home studio owner (uprights and digital pianos will be more common), which is why I'm going to keep it simple.
You can also use the M/S technique to great effect if you're recording piano at home. Raising the level of the side microphone will widen the stereo image, giving you great control of the stereo width during the mixing stage.
You could even use automation to have a slightly narrower piano during the verses and then a wider piano during the choruses - a little production tip that can help to give a chorus more impact.