The process itself is simple: First, eliminate the least powerful instruments. Then concentrate on the quality of sound, and finally on the action.
In a concert piano, sound is the primary criterion for selection. Of course, we want the pianist to like the action and to feel an artistic kinship with the instrument, because that increases the possibilities for musical self-expression. But in reality, the function of a concert grand is to sound good to the audience, with an abundance of power that allows it to perform a wide range of repertoire. Ideally, the best instruments possess both incredible sound and perfectly performing actions; but for the purposes of selection, the pianist must distinguish between these two elements.
Power and Projection
A concert piano should be chosen that can be heard above a 100-piece orchestra and whose sound will project to the rear of a large hall. Even though the piano might not be going into a 3,500-seat auditorium, it needs to be chosen as if it might. Why? Because any piano can be voiced for a smaller room, but a less powerful piano will be limited in the larger space. In the world of concert grands, one can never say for sure where a piano will eventually be used — it could be purchased for a small chapel, and end up one day being played in a concert hall. Because most buyers of concert grands are institutions, even a concert piano purchased for a home may one day be sold into a performance situation.
Piano tonal qualities can be explained by separating the elements of tone into four categories: pitch, timbre, sustain, and volume.
The pitch is controlled by the tuning of the instrument. This may seem obvious, but the terms used to describe piano tone can be confused with those denoting tuning. Pianists' verbal descriptions of tone are often completely different from those of technicians, and here communication can become confused. For instance, an instrument that a technician would describe as "bright" — that is, as having a more metallic tone — might be described by a pianist as "sharp"; which to the technician, of course, means that the piano is tuned higher than A-440.
The piano's timbre is a function of the relative strengths of the different harmonics produced by its vibrating strings. Think of timbre as the difference between a singer singing an A and a clarinet playing the same note. The notes are the same, but the sounds are completely different. Although timbre is influenced by the piano's scale design, most pianos can produce many different timbres — not just a simple bright or mellow — and this can be changed by voicing the hammers.
Sustain and volume are closely related to one another. These qualities — the direct results of the ability of the soundboard, bridges, rim, and bracing (the piano's "belly") to amplify the sound of the strings — create the ability of the piano to project sound to the rear of the hall.
For the purpose of selecting an instrument, the timbre is the least important tonal element, and should be considered last in the process. Most important is that the sustain and volume of the instrument must be assessed separately from the timbre, in order to differentiate between the sound-producing capacity of the belly, on the one hand, and the hammer voicing, on the other.
Sustain and Volume Tests
Here are a few tests that can be done by a pianist on any piano, in a concert hall or home, to evaluate the instrument's sustain and volume. They take very little time and will quickly narrow down the selection. To sharpen your ears and get you up to speed on the procedures, it's best to practice these tests on several pianos prior to the selection.
Play a note in each section of the piano at mezzo forte, holding the key down to keep the damper off the string. Keep a record of how long each note sustains. You may frequently run across references to how long this sustain should be. However, since every acoustical environment is different, you will get different results in different rooms. When choosing a concert grand, most likely you'll be trying out several instruments in the same dealer showroom or factory selection room. In that case, you'll simply compare each piano's sustain times with the rest. This test will be less conclusive if each instrument is in a different acoustical environment, but it's still worth doing as long as you take those differences into account when assessing the results.
Try another sustain test on the same notes: Pluck a string with the key depressed, so that the damper is off the string. (So as not to transfer body oils or sweat, I usually wear a latex glove for any tests that involve touching a string.) Test several notes in each section. At this point it will be instructive to compare the sustain when a string is plucked to the sustain when the same note is struck by the hammer. Technicians use this test to determine whether the source of a tonal problem is in the belly or the hammer. If the sustain is long when the string is plucked but not when it's struck, it means that the instrument has the capacity for good sustain, and that through the use of advanced voicing techniques, it may be possible to lengthen the sustain with hammer to match that of the string when plucked. But if the plucked sustain is short, then the instrument's capacity for sustain is likely limited, and there's probably little the technician can do to improve it.
Why is sustain so important? Legato playing, and the illusion of a "singing" quality in the instrument, lie within this parameter. If the soundboard can't sustain, notes sound staccato, and the connection of notes in legato is much more difficult to achieve. Although sustain is important in each register of the piano, most critical is the mid-treble section, in the fifth and sixth octaves from the bottom, for two reasons. First, this is the register in which, in most music, the singing melodic line is written. Second, for technical reasons related to soundboard design, this is tonally the weakest area of most soundboards. In my experience, concert grands can usually be made huge and beautiful in the bass, midrange, and high treble, but it's the fifth and sixth octaves that set apart the great pianos from those that are merely very good. To test this element, be sure to bring music that includes a soft, slow, melodic movement.
The volume of each instrument can be evaluated by holding the sustain pedal down and slapping the treble side of the piano's case. (You won't harm the piano structurally by doing this, but be careful not to damage the finish.) You can go from piano to piano and do this test quickly, but be sure to slap each instrument with the same amount of force. The louder pianos will make themselves evident by the greater din they produce.
In the middle of the keyboard, slowly hold down a C-major chord without letting the hammers strike the strings — just raise the dampers off the strings. Then, with the keys still depressed, forcefully strike and release a low-C octave in the bass. As the sound of the bass notes die away, you'll hear the original C chord singing sympathetically, even though those notes' hammers never struck the strings. Do this on each piano. Again, the louder pianos will become apparent through the volume of the resulting sympathetic sound.
The loudness of a string's sound when plucked is also an indicator of the piano's potential for volume. In the earlier sustain test in which strings were plucked, make note of any marked differences in volume among the instruments being tested. Be sure to use the same plucking force on each string.
Timbre, Hammers, and Voicing
As mentioned earlier, the timbre of the piano is the least important element of the tone for you to consider, in large part because it is the most variable and temporary, and the most easily changed through hammer voicing.
The hammers are the parts of a piano that change the most, wear out fastest, and as much as possible should be eliminated from your initial impression of an instrument. Like tires on a car, they're part of a performance piano for only a relatively short period in that instrument's life. The timbre of a set of hammers can change dramatically with the humidity, and any wear or maintenance of the hammers will change the piano's voicing. To maintain the tone of a concert piano, hammers must be maintained as often as the piano is tuned. Hammer wear is directly related to the number of hours a piano is played and the intensity of that playing. Hammers can last for many years if the piano is played only three or four times a year, but concert instruments in constant use can require new hammers after only five concert seasons.
Hammers can be voiced using an arsenal of techniques, including needling, ironing, hardening, or filing the hammer felt, and fitting the hammers to the strings. A good voicer can make a piano sound more mellow without reducing its volume, or can make it sound brighter but without harshness. Even when selecting among different instruments of the same make and model, you will encounter pianos with a variety of timbres. Try not to be swayed by this; to judge an instrument, keep returning to the basic tonal capacity of its belly for sustain and volume, and thus for power and projection.
That said, hammers that are voiced too bright will make the piano sound thin in the treble, and may obscure what might otherwise be a beautiful-sounding instrument. If, during selection, a piano sounds a bit bright, you might ask the technician to quickly voice it down, or at least address the notes that appear to you to stick out above the others. If the piano sounds too mellow but has a long sustain, you can be assured that it will be very easy later on to brighten it. But I want to stress that any voicing changes made during the selection process should be minor — for best results, the piano must be fine-voiced in the hall in which it's to be used.
Of course, any process of selecting among several pianos should include playing them — after all, that's why a pianist has been given the task. If high-level playing weren't a necessary part of the process, a technician alone could do the job.
However, a concert piano should never be chosen solely on the basis of how its action feels. Why? Actions can be changed, and they will change on their own anyway. The action of a new piano will change as soon as it is played in and settled: the felt and leather pack down, altering the regulation dimensions. I can't tell you how many times I've heard pianists say that they chose a piano for its action, only to complain, several weeks after delivery, that the action doesn't feel like it used to. But such changes are normal, and easily reversed with a minor touch-up regulation.
In addition, actions are very malleable, and can be adjusted in many ways to accommodate the player. If you love the sound of a piano but don't like its feel, ask the attending technician if he or she can correct whatever you find objectionable. Some typical action-related complaints — all of which, within limits, can be corrected or changed — include unevenness (requires some touch-up regulation to compensate for uneven compression of felt and leather), difficulty playing pianissimo (let-off needs adjusting), and key travel too shallow or too deep (set by manufacturer, but slight adjustment is possible). In most situations, assuming the pianos have already been well prepped, these fine adjustments can be made in a short amount of time while you're trying another piano. In my experience, however, if the piano has been regulated consistently from note to note and is within a reasonable range of touchweight, a pianist of high caliber will usually have no problem adjusting to its action. Just remember that what is most important is the instrument's sound. Trying to separate that sound from your response to the instrument's action is perhaps the hardest part of selecting a piano.
Dynamic Range. Starting very softly, play a note in each section, repeating it with increasing loudness, and count how many discrete levels of volume you can produce. The more levels you can produce, the more expressively you will be able to play.
Play fortissimo and listen to what happens. Does the sound "top out" — that is, do you want the sound to get louder but can't get the instrument to give you any more? Does the sound "break up," getting ugly and harsh when loudest? Or can you play as loudly as you like without harshness?
Touchweight and Repetition. The touchweight of a concert grand action should be between 48 and 55 grams, and most modern grands easily fall into this range. If you like a piano's tone, its action can always be made a bit lighter or heavier. If an action is too light, however, problems can occur with rapidly repeated notes. Many good technicians can't play fast enough to make an action fail in fast repetition, and so have developed action measurements and tests to ensure that these problems never occur when a good pianist plays demanding repertoire. But now, in the selection process, is the time to test repetition with some really fast passages.
After the Instrument Arrives
After you receive your new performance piano, you'll need to play it in for a while and let it acclimate to the hall. Your selected piano may need no adjustments on arrival, but any new piano will sooner or later need some touch-up regulation, and that can be done after a few weeks of playing. In my opinion, however, voicing should be delayed until the piano has been played extensively, so that everyone involved can agree on which direction the voicing should take.
After I have done the preliminary regulation touch-up, and made minor adjustments to even out the voicing without changing its character or volume, I usually invite two pianists to the final voicing: one to play, and the other to join me out in the hall, walking about and listening. I then make whatever voicing changes are needed, the pianists trade places, and we repeat the entire procedure until everyone is happy.
A piano will always sound a little different in the concert hall from how it sounded in the selection room. Halls that have been acoustically optimized for sound-reinforcement systems rather than for acoustic instruments can be especially challenging in the area of sound projection. However, I caution institutions not to jump to the conclusion that a piano's sound must be brightened if at first it seems a bit mellow. Not only will playing automatically brighten it over time, but most concert grands will blossom after a few months or several changes of season, and the piano will suddenly sound bigger and more robust. Indeed, if a piano is delivered in the summer and has been subjected to slightly higher humidity in shipment, it will take a few weeks in an air-conditioned hall before it sounds as it did at the selection. Patience in this regard is paramount. A good set of hammers can easily be ruined by overbrightening in response to initial complaints about a new piano's dullness of tone. Any changes in voicing should be made conservatively.
Special Considerations for Pianos in the Home
As mentioned at the beginning, even if a concert grand is being chosen for a home, it would be wise to choose one with plenty of power and projection, so that it can later be sold to an institution if desired. However, the issue of power and volume will obviously not be quite as important in the home as in the concert hall, and if the instrument is of less than concert-grand size, it will be less important still. In that case, more emphasis should be placed on the sustain tests than on the volume tests.
Institutional buyers are likely to buy a well-known brand based on its reputation, and its instruments' ability to be used for a wide range of concert repertoire. A purchaser for the home, on the other hand, is more likely to have narrowed down the selection to one particular brand after considering many, based on that buyer's desire for a particular tonal quality and the type of music he or she most often plays. Similarly, whereas institutional buyers must be primarily concerned with satisfying an audience with the sound of the piano rather than with its action, a buyer for the home is the audience, and thus, when shopping for an instrument, has more leeway to consider the action as part of his or her total musical experience.
Just as a concert piano will sound different in the concert hall than in the selection room, so will it sound different in the home. The home piano is usually easier to voice because projection is not a factor. However, the quality of sound will be substantially affected by carpeting, drapes, upholstered furniture, wall hangings, etc. A technician or acoustical expert may be able to help you adjust the acoustics of the room, and the piano's placement in it, for optimal results. In a home, owners often solve the problem of excess volume by closing the piano's lid. I encourage customers to let me voice the instrument to the room with the lid open. This way the piano can be played with the lid left open, and without excess volume, without stifling the piano's true tone.
If the brand chosen has a significantly idiosyncratic tonal palette, it's best to find, for follow-up service, a technician who has experience with that brand, and is familiar with its unique tonal characteristics.