Capturing the Wild Piano

Are you ready for a challenge? Take about 240 strings; stretch them across a mutant harp; attach 88 hammers, mechanical contrivances, and keys; mount
Author:
Publish date:

Are you ready for a challenge? Take about 240 strings; stretch them across a mutant harp; attach 88 hammers, mechanical contrivances, and keys; mount it all over a soundboard; put the whole mess in a giant wooden box; and make noise with it. Then grab a bunch of microphones and try to capture the true sound of the glorious, pulsating, ultimate acoustic music machine you've created. Intimidated yet?

Let's go further. The piano was created to be the ideal composing and performing tool, the entire orchestra at a player's fingertips. Consequently, the instrument has a vast frequency range, covering seven and one-third octaves with tonal color-that's way beyond the range of any other acoustic instrument. Its full name is pianoforte, which means soft/loud, reminding us that the dynamics of the instrument are incredible, ranging from the softest whisper of a single note to spine-jarring thunder in an avalanche of heavy chords.

That's only the beginning. There are dozens of different styles and sizes of pianos, from tiny uprights to monster grands, and each one has its own distinctive tonal character. When you add to these factors the instrument's condition, the recording space, the musical style, and the player's technique, you have yourself a monumental miking task. But if the instrument is in tune and working correctly, every engineer should be able to capture a usable sound from a piano in most situations.

DON'T ASSUMEDon't assume that an unfamiliar instrument is of good quality, in good working order, and properly tuned. Use your ears to explore the piano and the room. Be patient and methodical. If you suspect that the piano needs service or tuning, call a qualified technician. Don't try to do it yourself unless you're sure of what you're doing. And if the piano is really a mess, forget it.

This leads me to a point I hope you will take very seriously: you are not necessarily stuck with the instrument at hand. Pianists often choose a studio in which to record based on the sound and action of the studio's piano, sometimes even when it means accepting an inferior room. Classical pianists traditionally prefer a darker-sounding piano, such as a Steinway or Bosendorfer. Pop recordings are often suited to the brightness of a Yamaha or other typical Japanese-made pianos. Any piano recording benefits from a superior instrument.

The bottom line-if the piano at hand is not going to make you happy, don't use it. You can find good pianos in almost any town, so if you must, record somewhere else. Rent or barter for time in a room with a good piano, rent a good piano, or pay to have a friend's piano tuned in exchange for permission to record it. You and your client will have to live with this recording for a long time, so don't screw it up by using an inferior piano.

THE POWER OF TWOJudging from my experience and the conversations I've had with many recording engineers, it's almost always best to record piano with a combination of mics that results in a stereo recorded image. It's pretty much impossible to capture the full tonal, frequency, and dynamic ranges of a full-blooded grand piano, for example, in any other way.

Of course, an iffy upright might have so many faults that you want to limit what you pick up. In that case, careful placement of a single mic is the key. But you might be best off changing pianos.

THE PERFECT PLACELet's begin at the sublime end of the spectrum and talk about recording a fine grand piano in a special room. Three-time Grammy winner Ronny Cates, formerly of Christian supergroup Petra, now produces and engineers tracks for major-label artists at Mirror Image Recording Studios in Gainesville, Florida. Cates is proud of his 500-square-foot, "live" studio room with a floating floor and tailored acoustics.

"There are a million ways to record piano," Cates says. "The sounds required for classical and pop/rock genres are totally different. Classical tracks require much more 'air' and spatial depth in the mix than pop/rock, which usually needs to cut through electric instruments with a tighter sound and stronger top end. Bear that in mind, but it's best to put your habits on the back burner and alter your thinking for each individual artist-particularly in the eclectic pop/rock world.

"First, really get to know the piano in question, then consider strange combinations of sound sources. Maybe put a mic or two through a Marshall amp and mix the results with a natural signal. Listen to artists who are creative with such things: Ben Folds Five, for example.

"Whatever you do, remember the golden rule: Garbage in, garbage out. And stick to first principles. Take care with mic and polar-pattern selection, mic placement, room selection, and instrument positioning in the room. Forget about fixing in the mix. Get the right sound first. Take time to figure out where in the space available the piano sounds best for your needs. Note that this varies for each session, even under apparently identical circumstances. Never assume."

Cates's quick and easy starting point for getting the most natural sound out of the Young Chang baby grand in his studio is placing two Rode NT2 cardioids overhead in a spaced pair, 18 inches above the soundboard (see Fig. 1). The two mics aren't matched, but they're close to it. This placement picks up a lot of string and hammer-action noise and allows the recorded sound to cut through a mix, yet remain quite natural and airy. For this combination of piano and mics, Cates generally uses outboard API 3124 mic preamps with a bare minimum of compression and EQ.

Remember that, as with virtually all acoustic instruments, the true sound of a piano results from the interaction of its components (soundboard, strings, hammers, lid, and so on) in an acoustic space. Therefore, you capture the most natural sound when you mic the instrument from about six feet back.

To cut through a sonic wall of distorted guitar, try brighter mics-such as AKG C 414s or AKG C 3000s-in the same position. If you don't have a pair of good condenser mics, Shure SM57s can give good results.

Superior microphones portray the depth and spatiality of a piano dramatically better than other mics. The Rode NT2, for example, is a very nice mic, but you will hear the difference if you compare it to an appropriate higher-end mic from a company such as Neumann, Schoeps, or Earthworks. Similarly, when you replace a mediocre preamplifier with a superior preamplifier, the sonic improvement is impressive. You won't always have the option of using higher-end products, but if the session is important enough, consider borrowing or renting them.

The three-to-one rule of microphone placement instructs us to make sure the distance between the mics is three times greater than their distance from the sound source. However, as we are miking a single (albeit complex) source, the phase problems caused by breaking the rule are minimal.

Cates utilizes interesting surfaces-such as cloth, wood, and acoustic baffles-when he mics the room. "I often play with gobos, blankets, curtains, or whatever seems appropriate for molding the naturally occurring sound in the room," he says. "Sometimes it's nice to make a room like this sound smaller, with less-reflective surfaces. I often wander around the room while a player is practicing and find a particularly nice spot where the room and piano sound right. I'll mic that area, usually with another large-diaphragm condenser. I like large-diaphragm mics for piano. Or if I'm recording an ensemble live in this room, I'll mic the underside of the piano for a more contained sound. It's often w orth trying that in conjunction with overhead mics, too."

ON LOCATIONIf you are blessed with a great-sounding room that you can easily shape to your needs, you're fortunate. But most of us don't have that privilege, and we can record grand pianos only on location. I talked with noted longtime live-sound and recording engineer Taylor Johnson of The Sound Room in Hebron, Connecticut, about location-recording grand pianos.

"Most location grand pianos are 6- or 7-foot models, or perhaps a 5-foot baby," he says. "If you happen to come across a 9-foot monster, use the techniques I'm outlining here, but be aware that the piano is going to be incredibly resonant and, consequently, more difficult to mic. I put Sonex (acoustic foam), sound blankets, quilts, or what-have-you on the floor underneath the piano. I even pack foam beneath the piano's soundboard. You end up miking primarily the strings and beaters, eliminating almost two-thirds of the resonance.

"For an open, airy, 'classical' sound, prop open the lid on full stick. In a fairly resonant hall, I use a pair of small-diaphragm cardioid condensers in an XY [see opening photo] or ORTF pattern [see the sidebar "ORTF: The Basics"] pointed into the piano 'crotch' and about four to eight feet out from center. Remember that in this case the piano lid is directing some of the sound to the mics. If you set the mics close in, you'll likely get good midrange response, but you may find that the right-hand treble strings are outside of the mics' cardioid patterns. On the other hand, setting up far away will result in too much general reflection.

"Mounting the microphones at the height of the piano (four feet) will enable you to capture more reflection off the stage floor, but that might not help if the floor is composed of tile or stone. In that case, try putting the blankets underneath. Otherwise, try placing the mics eight feet high, past the point of reflection off the piano soundboard and, of course, floor reflection.

"The idea is to balance the reflections of the hall and the attack of the piano," Johnson continues. "Other factors are the player and style of music. Use your ears to find the right spot, try the mics there, and make adjustments as common sense and intuition direct you.

"You might also try a spaced stereo pair of large-diaphragm condenser microphones, but those will pick up a lot of ambient resonance off the stage and hall. That's good if the hall has exceptional acoustics, but having a great hall, fine piano, good stage, wonderful player, and perfect material is rare."

A Tough RoomYou should usually consider close-miking only when the space detracts from the sound of the instrument, when you want isolation (while recording a live band, for example), or when you want the mechanical aspects of the piano, such as the hammers, to be integral to the sound. Close-miking isn't recommended for baby grands under any circumstances because they are strung loose and tend to rattle and bang.

Johnson offers several approaches to close-miking. "I tend to use a pair of small-diaphragm cardioid condensers," he says. "My favorite method is to place the mics about four inches above, and parallel to, the soundboard and prop open the lid with the short stick (see Fig. 2). I put one mic at the second sound hole from the side, pointed at the hammers or at the center of the keyboard. I generally put the other mic near the fourth sound hole from the side, pointed across the strings at or close to the place where the bass strings cross the mid strings. Some engineers put the second mic on the opposite side, at the other point where the strings cross, but I find that way too bassy."

Another technique is to tape PZMs to the lid in the same positions Johnson suggests for small-diaphragm cardioid condenser microphones (see Fig. 3). Although the short stick is recommended in this example, you can also place the lid in an almost-closed position. (For more information on PZMs, see the sidebar "Performing Under Pressure.")

If your session is in a particularly bad space and you are recording without an audience, consider setting your microphones inside the piano. Wrap the body of the piano with acoustic blankets, quilts, packing blankets, comforters, ordinary blankets, or any other soft material that feels appropriate. I call this the "woolly mammoth" approach, and it often works, even in the most difficult spaces. An added benefit of the technique is that it almost fully separates the piano from other instruments.

UPS AND DOWNSThe tip I've received most often on recording upright pianos is to not do it at all. It's almost impossible to get a convincing piano sound from an upright, even one that's beautifully built and in perfect working order. In an upright, all the hardware of a grand piano has been shoehorned into a tiny space, which makes it difficult to separate the mechanical noises from the music. If you're looking for that tinkly, honky-tonk, hammer- and pedal-heavy upright sound, you can get it. You can even paint the hammer felts with nail polish or stick thumbtacks into them to accentuate the piano's trebly hammer-attack sound. But you'll have difficulty achieving a natural sound.

Unfortunately, an iffy upright in a difficult space may be your only available option. So here are a few tricks and tips that might help.

Harvey Gerst of the Indian Trail recording studio in Sanger, Texas, is a gold record-winning songwriter, studio musician, recording engineer, producer, and microphone designer. He recommends that you move an upright away from any walls in the space and mic the back of the piano (see Fig. 4). "If you can't get it away from the wall," Gerst says, "angle the piano so it's not parallel to the wall. Use your ears to find any spots that ring-which is a particular problem with uprights-and find the spot that rings least. If that doesn't work, try to mic from farther away, at the position that works best for you."

Johnson adds: "Some of the best recordings of uprights have been made by miking restored player pianos that have the machine works removed and the piano-roll door left open. You access the sound with a single, large-diaphragm condenser microphone, directly off the soundboard. I've gotten the best results from a pair of cardioid-pattern, small-diaphragm condenser mics, one at each end of the fully open top. You also might want to take off the front above the keyboard, particularly if only half the top opens (see Fig. 5). An alternative is to place a similar XY pair above the player's head, about six inches in front of the opening."

PANDORA'S BOX?We've barely scratched the surface of an enormous subject. Much depends on your insight, patience, ingenuity, common sense, and-most important-ears. But if you have a sufficient supply of these virtues along with the appropriate electronic equipment, you can get a usable sound wherever you record and-within reason-with any instrument.

Elizabeth Papapetrou has been writing for music magazines and recording for 17 years. She loves microphones and focuses on recording solo and small-ensemble acoustic music.

A PZM (pressure zone microphone), or boundary microphone, is an omnidirectional microphone capsule (typically an electret condenser) that is fixed very close to a flat surface, at a distance shorter than the wavelength of the highest frequency to which it responds (see Fig. A). At the surface, or boundary plate, reflected and direct sound effectively act as one reinforced signal, eliminating time-displacement effects (that is, comb filtering).

Due to the boundary, rear rejection is 100 percent. The boundary converts the capsule's omnidirectional polar pattern into a hemispherical pattern, with the boundary plate determining the hemisphere's equator. The result is a great ambient-recording microphone. It's particularly nice for concert recordings and for adding color.

Low-frequency pickup (below 350 Hz, for instance) drops off if the wavelength is longer than the boundary plate, so if you have the 5 by 6-inch plate typical of some Crown PZMs, you might want to mount it on a larger plate (2 by 2 feet, or even 4 by 4 feet). These mics become directional at high frequencies when mounted on a small surface.

Boundary microphones were invented in 1980 by Ken Wahrenbrock, a ham-radio enthusiast who was asked to do a lot of live, spoken-word recordings. Frustrated with ambient-mic techniques of the time, he decided to develop a microphone that worked more like the human ear. Wahrenbrock's breakthrough came when he discovered that one main difference between a conventional microphone and the human ear is the ear has a pressure gap beneath the eardrum that makes part of the ear act as a reflective boundary. This led to experiments with flat boundaries and small condenser capsules. Well-known engineers Ron Wickersham and Ed Long later helped refine Wahrenbrock's design and develop it into something th at could be controlled and manufactured easily. Their design was licensed by Crown International, which is still a leading manufacturer of PZMs.

In 1981, Wahrenbrock demonstrated prototypes of his new microphone for Frank Zappa and Zappa's personal-studio engineer, Mark Pinske. These days Pinske engineers and masters at Skylab Studios in Gainesville, Florida. "Ken brought us these weird-looking mics, and we were blown away by them, particularly for ambience," recalls Pinske. "The first thing we recorded was a big, five-octave bass marimba. It sounded awesome through the PZMs. We worked with Ken on development for two years and did all sorts of crazy things with the mics.

"Sometimes Frank recorded his solos on PZMs in an empty concert hall because he liked the natural reverb, and we dropped them into recordings later. For five years we kept the PZMs set up behind the P.A. cabinets-one stage left, one stage right-in order to get an ambient audience sound that was similar to what Frank heard on stage. Then, in 1984, we recorded Orchestral Works using 30 or 40 PZMs, trying all sorts of weird Plexiglas constructions to change the boundary characteristics. We put them everywhere: scooplike plastic dishes over violin stands, little wedges that sat on the floor in front of the cellos and basses, and big 4-by-4, Plexiglas sheets that hung from the wall behind the per cussion. It was awesome."

Further technical information about PZMs is available in The PZM Boundary Booklet, free from Crown International (see Contact Sheet on p. 175). -Elizabeth Papapetrou and Steve Oppenheimer

With ORTF miking, you place a pair of cardioid mics about 6.69 inches apart and facing outward at a 110-degree angle (see Fig. B). The mics are aimed at the left and right edges of the sound source. The perceived spatial position of the source is achieved through sound intensity as well as phase differences.

The greater the angle of the mics, the smaller the stereo image. This is because turning the mics outward exposes more of their off-axis sides to the source. When the mics are at a tighter angle, the source is more on-axis to both mics.

In general, ORTF (short for Office de Radiodiffusion Television Francaise, the French government radio network that developed the technique) is easy to use and gives good spatial definition. It also produces a very pleasant sound with a lot of depth that warms the brightness of small-diaphragm microphones. ORTF works better with small-diaphragm condenser microphones than with large-diaphragm microphones, which have a relatively weaker off-axis response.-Steve Oppenheimer