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In the Studio: Close-Miking An Acoustic Grand Piano

When and how to use it, and a range of techniques

By Charles Szczepanek March 15, 2013

This article is provided by the Pro Audio Files.

In a world of sampled instruments and MIDI sequencing, recording an acoustic grand piano is not a task for the faint of heart.

Most engineers can rely on an instrument package, like Garritan’s “Authorized Steinway” or “Ivory” for nice sounds.

However, when a piano needs to be the primary focus of a mix, or when you have a very serious player in the studio, you will need a well-maintained acoustic grand to make the best possible recording.

Miking a grand can be a daunting task, so I hope I can ease your mind by explaining a few techniques and tricks that can help you record a great close-miked piano.

When To Use It
The piano sound you will most often hear in pop music and in jazz is the close-miked sound. Not only does it help eliminate bleed if the piano is recorded in the live room with the rest of a band, but it also gives the mix engineer a wide range of choices to help what usually is the physically largest instrument fit into the mix. There is very little room in the sound, and the room that does exist is most likely faked with a hardware or software reverb.

A variety of miking techniques can be used to achieve different sounds from percussive to balanced, from narrow to wide, and from bright to mellow. The closeness of mics is what makes the sound both the easiest to achieve, and yet also makes choosing an appropriate technique very difficult. As this sound is the most commonly sought after in the studio, it makes a perfect starting place for us.

Brief Anatomy Of A Piano
Before we begin talking about sound and how to record the sound of a piano, we must first understand how that sound is produced and naturally amplified by the instrument. The diagram to at right illustrates a few of the most important parts on the inside of a piano.

Depressing the keys of the piano starts a very complex lever in motion, resulting in the hammer striking the string, which in turn results in the sound we hear. Hammers are located below the dampers, as you can see in the diagram. They are covered in a semi-soft felt that provides a variety of tones depending on the speed at which the hammer hits the strings and also the age and use of the instrument.

(click to enlarge)

In general, the faster a hammer hits a string, the more its felt is depressed upon contact, creating a harder surface and a brighter and louder tone. That tone then resonates through a precisely crafted soundboard, the wooden bed that runs the entire length and width of the instrument.

The bridge, as seen in the diagram, is not just a point at which strings are connected, but on many good instruments, the length of string beyond the bridge is capable of vibrating and can help produce extra overtones and in general a ‘bigger’ sound.

There are plenty of resources to learn about the whole mechanism inside the piano, but I think the above points are the most valid for starters. Now let’s dig into some more meaty information.

As there are quite a few techniques we will cover here, we will organize them by starting with the techniques that are used nearest to the hammers, moving toward the bridge and tail of the piano as we go.

Keep in mind that all of these techniques use microphones “under the lid” of the piano, very close to the strings themselves.

1) The Percussive Rock Piano
This technique highlights the percussive nature of the instrument by placing mics nearly on top of the strings over where the hammers strike. It is useful for very busy rock mixes where the piano needs to be heard but doesn’t need much depth. You can place mics in XY, ORTF, and AB spaced pair (allowing a variety of stereo widths), and you can also feel free to use pretty much any polar pattern, except figure-8.

Always keep in mind that a true omni will accurately hear down to the lowest bass the instrument can produce, while many cardioids have some sort of roll-off. Also, true omnis will not exhibit the proximity effect, while cardioids will.

The distance from the strings that the mics are placed will determine how percussive the sound is: the closer, the more percussive; the further, the more balanced. By “close” I mean as close as just a few inches from the strings, and moving further away from there.

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