Piano Tuning Procedure

Source: Singapore Piano Shop sell YAMAHA KAWAI piano

Published: 4/8/2011

Before you begin, clear the area of other humans. Turn off all other sources of sound, especially things that "hum." Lock the doors. Prop the piano wide open. You may need to remove some of the cabinet members; they are designed to be easily removed with no more than a screwdriver. Position your light source.
 
Piano Tuning Step 1: Tune a single string from a single note in the middle octave.
The middle octave is "middle C" also called C4, upward to C5 . Each piano key strikes one to three strings. Pick one string to tune at a time; if three strings, start with the middle. Carefully find the pin that turns the string you want to tune. Stick the rubber wedges in to stop the vibration of the other one or two strings in the set. While repeatedly striking the piano key FIRMLY, turn the pin with the tuning lever VERY SLIGHTLY until the electronic tuner shows that it's in tune. The Korg CA-40  automatically detects the note you are trying to reach. If you are really off, it may show the wrong note, so make sure you know what you are looking for. Alternatively, the CA-40 can also play the tone for you to match by ear. More about matching by ear in Step 2.
 
Tips about this process:
 
Tuning lever socket must be securely placed on the pin. The pin will bend, marr or even strip corners if the tuning lever socket is not seated completely. The handle should have no side to side movement when properly seated; the only direction of movement should be a radial turn.
Proceed slowly. Stretching a string too quickly can break it, especially an old string. If the string is really far out, you may want to tune it in several steps, allowing it to rest a few minutes between turns. (Thanks to a reader for pointing this out.)
Righty Tighty, Lefty Loosey! Turning the pin right/clockwise will tighten the pin and raise the pitch. Turning it left/counter-clockwise will loosen the pin and lower the pitch.
Do not overwork the pin. Twist it gently, little by little, without bending it. Don't wiggle it side to side in any way. Move the pin as little as you can (you'll get better with practice.) Too much twisting and wiggling can loosen it; a loose pin will keep slipping out of tune. Rough technique may permanently loosen pins. Loose tuning pins will need to be replaced by a professional.
Listen carefully for a change in tone when you begin turning the pin. You should hear a change in tone with even the smallest movements. If nothing changes, stop to make sure you are on the right pin.
Loosen the tension (turn left) a little first before tightening (turning right). Better to relax the string with your first movement, than to overtighten needlessly, especially if you happen to be on the wrong string! Overtightening breaks strings, and is a common error for inexperienced tuners.
Establish a pattern. Develop a consistant sequence for each note, e.g., middle string--right string--left string etc. You will eventually learn the pattern for what string goes to what note, you be less likely to choose the wrong pin, and you will not as easily loose track of what you have tuned. It does not have to be the order we give you; pro tuners have their preferences, too
About "Setting the Pin." Setting the pin means to move it in such a way that it does not easily slip back out of tune. To set the pin your final tuning movements should be:
a slight tightening/clockwise move to stretch the string just a hair above pitch
followed by an even slighter loosening/counterclockwise to move into pitch.
This is where practice comes in. The better the tuner, the better he or she is at setting the pins, and the longer the piano holds tune. As a novice, your piano probably won't hold tune as long because of this important skill.
Strike the key very firmly. The vibrations this creates equalize the tension along the string. A string firmly struck while tuning will stay in tune longer. If you tune by playing softly, the string may relax later when someone does play it hard, and it will slip out of tune. If you like, you can begin your tuning of each key with gentler hits; striking it hard all the time is exhausting and irritating to the ear. When you think you have it, hit it hard a few times as you finish the final touches.
Tune to the "early" tone as you strike. As string vibration diminishes, the pitch will change slightly. Tune to the first, loudest sound made. Strike again if the sound begins to taper before you finish tuning.
As you tune with an electronic tuner, particularly an inexpensive one with its low resolution, jumpy LCD needle, you will find it nearly impossible to hit dead on the frequency each time. I tend to stay let the needle hover just a shade sharp when in doubt, as pianos generally go out of tune to the flat, not the sharp anyway. Note that I am not deliberately tuning sharp; rather I am avoiding erring flat due to the limitations of the display. (In some humid climates, a piano may temporarily go out of tune to the sharp as the air moisture swells the soundboard, pulling the strings tighter. However, even here the change from humid to dry to humid will result in relaxed, flat strings over time.)
 
Piano Tuning Step 2: Match the remaining strings in the note to the one first tuned.
After the first string is tuned, it's time to match the other string or two in the set to the first; this is called "tuning the unisons." Move the mutes so that the first, tuned string and a second string are free, but the third, if present, is still dampened by a mute. Ignore the tuner; tune the unisons by ear. Put your wrench on the second string's pin. While repeatedly striking the key hard, turn the second pin until you can hear no more "beats"--that is, it sounds like one note, not two in disharmony. Repeat for the third string if necessary, with all rubber mutes removed.
 
If you are not sure what to listen for, here is an mp3 (104k file) I recorded of a piano note being tuned. (Javascript Pop-up window.) In the recording, I start with an A4 that is in tune, then use the tuning lever to loosen one of the strings out of tune, then bring it back in tune again. Disclaimer: In order to demonstrate in this mp3, I have turned the pin much more than is healthy for the pin. Move your pins as little as possible to avoid loosening them.
 
Do not try to tune the unisons with the electronic tuner. It's all but impossible to get a match that way. Tuning the unisons by ear is the quintessential tuner skill; no electronic tuning device can replace it. For more on tuning unisons and handling the lever, see our blog.
 
Repeat Piano Tuning Steps 1 and 2 for each in note from C4 to B4. When you have completed this first octave, you have "set the temperament." In Step 3, you will use this first octave as your reference for the rest of the piano.
 
Piano Tuning Step 3: Use the first octave to tune the others by ear.
Do not use the electronic tuner. Tune the octaves above and below the middle by ear, matching them to the middle octave, e.g, A4 to A5, B4 to B5, etc. Tune one string in the note at a time (muting the others)--this time comparing it to the corresponding note in the middle octave rather than the electronic tuner. Then tune the other string(s) within the note (the unisons) to the first as described above. Work your way outward. Always using the temperament octave as your reference tone to minimize the chance of magnifying an error or peculiarity in another octave. However, do compare the various octaves as you go to make sure everything is blending as it should. As you get to the extreme high and low octaves, it becomes harder to hear precise differences between the temperament and the target note. If in doubt, err on the sharp side for upper octaves, and on the flat side for lower octaves for the best sound (see "Finer Points" below.)
 
What if I just want to tune A2 or B6 or something?
Tune the corresponding note (e.g. A4 or B4) in the middle octave to use as a reference. Note: if you have an electronic tuner than can show frequencies or play reference tones for octaves other than the middle octave, do not use it to tune anything but the middle octave. If you use the A2, for example, on an electronic tuner that is not specially designed for piano tuning, you will not get a good result because of "inharmonicity."
 
Why not use the Korg tuner to tune everything?
Even if you tune every note perfectly with a simple electronic tuner like a Korg, you will not get a very pleasing result. The different lengths and types of strings in a real piano tend to alter their resonant characteristics from the ideal. Tuners call this phenomenon "inharmonicity." The mathematically-calculated equal-temperament pitch actually sounds out of tune for many keys, getting worse the further you are from the middle, and moreso on smaller pianos with shorter strings. In a piano that has been entirely tuned with a simple electronic tuner like the Korg, the top registers will sound flat, and the bottom registers sharp. In practice, only A4 (A above middle C) is tuned to a outside standard pitch, 440 Hz; all the other keys are tuned relative to A4. In fact, a purely aural tuner may just tune the "A" with a tuning fork and tune the rest by ear.
 
In our simplified method of piano tuning, using a simple electronic tuner to tune the temperament, then putting it aside to tune octaves by ear will get you closer to proper adjustment automatically because it will "sound right." This more closely approaches what a professional piano tuner who tunes by ear does. See "Stretching Octaves" below. If you desire an electronic tuner to tune every octave, then you will need a professional piano tuner's electronic tuner or software like TuneLab, though professionals tuners using these devices will make further adjustments.
 
Finer Points of Piano Tuning
Stretching Octaves: To tune a piano exactly right, one must "stretch octaves," which is to intentionally tune upper octaves progressively sharp and lower octaves progressively flat. Electronic equipment and software can help a professional piano tuner calculate precise stretch frequencies, but these tuners are expensive, and even then a professional tuner will often adjust it from the calculated value anyway. In our method, we are tuning the entire middle octave to an outside standard, which is not the best, but these notes are stretched very little if at all. Furthermore, by tuning the remaining octaves by ear, we tend naturally to stretch the octaves because it "sounds right." This mimics the technique of a tuner who tunes by ear. Stretching is required because the physical differences among strings (length, construction) make them respond differently from the ideal; stretching in effect customizes the sound to the peculiarities of each piano. For example, small spinets need more stretch than giant concert grands.
 
Equal Temperament: The most popular modern model for the frequency for each note is called "equal temperament." Equal temperament is designed to give the overall best sound no matter in what key a song is played. Ideally, the "perfect" piano will be tuned with mathematically calculated frequencies that have precise intervals between notes determined by the equal temperament model (though in practice the octaves must be stretched, see above.) Many different temperaments, or piano tuning schemes, have been developed through the years. Some are experimental; others deliberately favor certain musical intervals. Interestingly, composers of the classical period composed for pianos that were not tuned to equal temperament but to one of several other temperaments popular in their time.
 
This chart demonstrates how far (in cents) from ideal equal temperament (straight, horizontal line at zero) the high and low octaves are "stretched" on a typical piano (curved, bright red line). Notice that the middle octave (4) is barely stretched, which is how we can "cheat" with an electronic tuner on the middle octave. Further note that how much an example of an actual piano (light, jaggy line) varies even from the expected stretch (curved, bright red line). Even in the middle octave tuners make small adjustments, which is why our method of tuning is not ideal. A really good ear will be able to tell the difference.
 
 
Pitch Raise: In a piano that has been out of tune a very long time, the lack of proper tension on the soundboard by the many strings may physically change the shape of the board from the original design. When you tune it, it does not hold tune well because the misshapen soundboard warps in irregular ways: the notes you have already tuned go back out of tune as you tune notes elsewhere. If you find this is the case for you, the remedy is a pitch raise. This is a special way of tuning the entire piano roughly to stabilize the tension on the soundboard, then fine tuning after it settles. Pitch raises are beyond the scope of this tutorial, but now you have another reason to keep your piano in tune.