Equal temperament

When tuning a piano for the first time, I record all the separate keys using computer software and a good external condenser microphone. This only needs to be done once.
After this, the computer calculates how this particular piano can be tuned as good as possible. In other words: how to achieve the best tuning level and how to minimize the entropy (disorder, degeneration) between all pitches.
The hardest part of tuning a piano is not necessarily making a tone sound good, but making sure that all pitches are in the best possible ratio to each other. We call this equal temperament or equilibrium temperament. The computers accuracy of calculating this best possible ratio cannot be achieved with human hearing.

Concert pitch

The way to go is always to make sure that the ‘A’ of the fourth octave is set to 440 Hz. This is defined as being the concert pitch. This is of great importance for both the builders of musical instruments as well for musicians themselves. It makes playing with other instruments possible.
Some pianists prefer to have the concert pitch set to 442 Hz. It supposedly makes the sound of a piano more bright and brilliant. I tried this, but I truly don’t hear any difference between 440 Hz or 442 Hz. Nevertheless, it is by no means a problem to tune the piano to 442 Hz. However, ideally you should not raise or decrease your specific concert pitch too often: it does not improve the tuning stability of the instrument.

Tuning hammer

I use a Jahn tuning hammer because this hammer allows me to tune in the best accurate way.  A key is tuned by turning the tuning pin. If the tuning hammer even slightly bends, not all the energy will transfer directly to the tuning pin. The Jahn tuning hammer is made of carbon fibre, also known as graphite fibre. This material is stronger and stiffer than steel, but also much lighter. It allows the piano tuner to transfer the energy of their tuning hammer directly to the tuning pin, making it possible to tune the key more accurately. With my Jahn tuning hammer I am certain that there will be no energy loss because carbon fibre can’t be bend. So it is straight, or it is broken. I love this tuning hammer and I would not like tuning a piano without having this specific tool.

Very far out of tune pianos

Sometimes it isn’t possible to tune the piano directly to 440 Hz. This is often caused by a piano not having been tuned for a very long time (several years in a row). It can also be caused by the age of the instrument. This causes the tuning level to drop, sometimes over (half) a tone.
If this is the case with your piano, the risk of breaking a string is very high if one raises the piano immediately to concert pitch. Also the tuning level will not hold long, due to the large difference in tension on the strings before and after such tuning. This piano will sound untuned again very quickly. If the piano is old or has not been tuned in a very long time I prefer to tune the piano in two or even three sessions. This allows the piano to gradually adapt to the higher string tension.
Sometimes the piano can no longer be tuned properly due to mechanism failure, a damaged soundboard or other problems the piano is suffering from. Should this be the case, I will report it to you immediately.