Tuning technique

Find out more here about how a piano tuner tunes a piano and what tuning techniques are available:

When you press a key on your piano the hammer strikes up to three strings – the string set or chorus – simultaneously. The tension and pull of these strings change unevenly over time and strings no longer vibrate at the same rate: you hear an out-of-tune tone in which the volume increases and decreases (beat). The high notes of the piano „screech“ or clink when they are out of tune.

When tuning the piano, the piano tuner matches the notes to each other

When tuning the piano, the piano tuner matches the pitch of the individual out-of-tune strings so that together they produce a balanced sound. The strings of a chorus must be tuned to each other and the choruses or piano notes must be given balanced pitches or intervals. If the two or three strings of a choir do not sound equally high, they sound impure and unbalanced and and lose its clarity and purity. In the low bass range, the piano tuner only has to tune one 99.9% copper wound thick string to each of the upper notes. The piano tuner can tune lower notes more easily than higher notes which have to be adjusted much more finely and whose changes in pitch are more easily perceived by the ear. The piano tuner uses a tuning key and tuning wedges made of wood, felt, rubber or plastic as aids. The piano tuner dampens certain strings with the wedges so that only one or two strings vibrate freely and can be adjusted to each other with the tuning key placed on the tuning nail. In the picture below you can see how the piano tuner has pressed a red felt band between the groups of strings: This makes it easy to tune the middle strings of the notes. Subsequently, the piano tuner removes the tape and the remaining strings are adjusted to the tuned middle ones.

This matching requires a fine and experienced ear in piano tunings; it is not always easy for the tuner to stop the turning movement of the tuning key at the right moment because some „elastic“ strings require the piano tuner to slightly over-turn them so that they then fall back into the correct position. It is also difficult if certain (e.g. middle) reference strings of a string set sound discoloured. The piano tuner then has to pick out the least discoloured sounding position and adjust the string to be adjusted accordingly – in other words, the tuned two or three strings of a piano key still sound slightly impure in such a situation, without the tuner being able to tune them completely pure.

The piano tuner tunes the individual key notes to the correct pitch so that they have the purest possible sounding intervals between them. One tone is used as a reference from which all other key tones are tuned to the corresponding pitch: the concert pitch a1, which in Switzerland is set by default to a frequency of 440 to 442 Hz (Hertz, vibration per second). Pianos or grand pianos that have not been tuned for a long time have an a1 that is often in the range towards 435 Hz. The piano tuner can tune the piano 1 to 2 Hz higher for each tuning. If a piano sounds a semitone too low in relation to the concert pitch, it needs two tunings to bring it to the correct pitch: First, all the strings are raised, e.g. to a1=442 Hz. Then, a few days later, in a second operation, all the strings that sound slightly lower again are retuned according to a1=440 Hz.

Pianos and grand pianos are tuned in equal temperament

In equal temperament – which has been used since the 19th century on practically all keyboard instruments such as the piano, organ and harpsichord – the octaves are divided into 12 equal semitones of 100 cents each and a constant frequency ratio f2/f1 of about 1.06 (thwelfth root of two). All semitones are tuned in a ratio of 1 : 1.06 to each other over the entire keyboard (in the lower and higher registers, however, the ratio is slightly altered). In equal temperament, the octaves are divided into 12 semitones of 100 cents each. A tone to the next higher semitone by a factor of 1.06 is thus tuned over the entire keyboard (though not continuously in this order). The advantage of this equal-tempered piano tuning is that piano pieces sound and can be played in the same way in all 12 pitches and that no pitch or key is favoured or disadvantaged. The disadvantage is that only the octave sounds pure, but the other intervals receive a slight beat.

The fifth and fourth (they are closest to the octave) sound relatively pure, but a slight beat in the seconds, thirds, sixths and sevenths cannot be overheard. Pure intervals with an integer frequency ratio can be reproduced by fretless instruments such as the violin or cello, because the player can press the exact pitch with his fingers. Wind players can also blow more precise pitches because they can influence the pitch with the blowing technique. On the piano, the pitches in the equal temperament tuning are tuned a little too tightly compared to the ideal of pure intervals. This is because a sequence of 12 pure fifths does not result in exactly the distance of 7 pure octaves – it is about an eighth tone (Pythagorean comma) too high.

The equal temperament tuning is slightly changed

With the help of his hearing, the piano tuner can also align the resonating overtones (as they can be heard particularly clearly with the pianos) with each other. When a piano is tuned in unison, the overtones of the low notes sound out of tune compared to the fundamental tones of the high notes; The reason for this is the fact that piano strings are not 100% elastic and their overtones do not sound completely pure. To solve this problem, piano tuners use the so-called stretched tuning, in which the low notes are tuned lower and the high notes are tuned higher. This technique matches the overtones of the low notes with the fundamental tones of the high notes and beautifies the sound of your piano or grand piano. Thus, however, the notes are again slightly out of tune with regard to the same piano tuning, which shows the dilemma of the perfect piano tuning. When tuning the piano in Bern, I use this technique for all pianos. Grand pianos are less „stretched“, i.e. warped, because their strings are longer and come closer to the ideal, infinitely long string.

Call the piano tuner once a year or more

When buying a new piano, the wood and the cast iron frame, on which a string tension of up to 20 t rests, must first get used to the microclimate of your apartment. Expect two to three piano tunings in the first year. A few years later, it is enough to summon the piano tuner once a year. Factors that cause your piano to detune are:

– room temperature fluctuations,
– the general condition, age and quality of the piano,
– the time for which the piano has not been tuned,
– the question of how often and how loudly you play on your piano or grand piano.

The last point in particular became clear to me once during a piano tuning, when I was Michel Camilo’s grand piano tuner at the Bern Jazz Festival in 2007. He hit the keys so hard that I had to retune the grand piano for half an hour after each concert in a series of 10 tunings. In summary, this means: Have your piano tuned by the piano tuner every six months for the first two years after moving into your new apartment and annually from the third year onwards. If you let your piano tune less often, it will lose its original pitch, which is adapted to the tone a1=440 – 442 Hz.

Piano tuner since youth

I gained my first experience as a piano tuner in my youth. Later I deepened my knowledge in a piano building studio in Bern-Bümpliz. Since 1990 I have been tuning pianos and grand pianos in Bern and the surrounding area included Fribourg, Thun etc. I worked as a concert tuner for Michel Camilo during a jazz festival at the Marians Jazzroom in Bern.