The Piano can be one of the most difficult acoustic instruments to record accurately, but it’s not impossible with a little determination by using the correct microphones and its techniques.
Recording in stereo using two microphones is the easiest technique. However, if you only have one microphone, placing it above the strings of the piano about 2 to 3 feet above middle C will give you the best well-adjusted balanced sound.
The choice here is to use a matched pair of condenser microphones if you have them; otherwise, any two condenser microphones will do the job, you will have to be precise of microphone placement. Condenser microphones have the wide frequency response, low self-noise, and sensitivity that captures the tone of Piano requirements.
Let’s take a look at the procedure for stereo recording using two microphones.
Open the top of the Piano to expose the strings, and place one microphone about 12 inches above the strings facing slightly inward around the second G below middle C, then take the second microphone, same distance up, above the second G above middle C, same technique as the other one. Pan the microphones hard right and left.
This should give you an acceptable sound; remember every Piano and every microphone is different, so grab these tips and experiment with the microphones you have. You might find something that works perfectly for you but sometimes it might not work out so great for someone else.
If you have got a limitless budget, there are lots of great options in the recording scene for you. One of my favorites is to use a Shure Beta 91 microphone inside the piano, with a stereo pair of microphones outside to capture the ambient sound of the piano. This allows you to fine-tune your recording which will provide you more of what you are searching for, and less of what you don’t.
You may also notice that, sometimes despite of your best efforts used, you are not getting the correct sound from your Piano; that is awful tuning and dreadful room acoustics are among the two causes of shocking (muddy) acoustic Piano tracks. In this situation, you might consider using an electronic Piano instead. In this way you will achieve the option for a better mix for all your song and perform your final mix in tune with other musical instruments and vocals.