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Tuning- How it Works

Updated: Aug 25, 2023

Before I became a piano technician, I can’t say I wondered too much about how a piano was actually tuned. I knew a piano had strings, but that’s as far as I got. As I was learning more and more about how pianos work and their anatomy, it was so much more intricate than I could’ve imagined.

So what am I actually doing when I’m tuning? What does tuning entail? Let’s dive in!

First, most keys in your piano are actually playing more than one string. As you might know, there are 88 keys in a typical piano. But did you know that pianos have about 230 strings?? This is something I had no idea about before I started on the path to become a piano technician. So why are there 230 strings and how do they work with each other?

I’ll start by saying that for the low bass notes, there is one string per key, a 1:1 ratio. However, those bass strings are quite thick and are actually wrapped with copper wire. Bass strings are very special in this way—if they were not wrapped the way they are, that string would need to be several feet longer in order to get the low bass tones you are used to hearing, as the length of the strings directly correlates to the tone of the note it produces- the longer the string the lower the sound, the shorter the string, the higher the sound.

Moving up the piano from the lowest bass notes we begin to actually see two strings per key. This grouping is called a bi-chord. When you play a key that hits a bi-chord, it hits both strings. And believe it or not, when you keep moving up the piano, the two-string bi-chords then become three-string unisons, which there are the most of out of any string grouping in pianos. So most notes you are playing actually have three strings the hammer is hitting.

Maybe now it’s becoming clearer how pianos can easily come out of tune, as there are 230 strings that need to play in perfect harmony with each other, and even more so, there are groupings of strings, the unisons, that need to sound exactly the same so they are indistinguishable from each other while being played.

So—here we are, the big question: how do you tune a piano?

The first step in tuning is to get a reading of where the piano is tuned to in that moment; see how in or out of tune it is so we can determine if the piano needs a pitch raise. Next, I set up my hygrometer so it can get a reading of the temperature and humidity level of the room the piano is in, as these factors greatly affect the tuning stability of a piano.

While the hygrometer is acclimating, I apply my strip mute to the piano. My goal here is to mute off the strings of the unisons so that only one string in each unison is exposed. Meaning, in a two-string unison I want to mute one string, and in a three-string unison I want to mute two strings. This leaves exactly one string exposed for every key in the piano (Bass strings are not muted because there is one string per key, and if they’re muted, I couldn’t tune them).

With the piano muted, I can do finer tests to see how the notes relate to each other tonally. I will use this information to determine how best to tune the piano. Each piano is slightly different, even within the same brand, even within the same model.

Ok, I’m all set to start!

I tune aurally, meaning by ear. It took many hours of practice to be able to tune this way, and I love every second of it. I start with tuning a temperament, which in my case, means an octave in the middle of the piano. After I've completed my temperament sequence, I will then tune the octaves up the piano to the top, and then down the piano to the bottom.

So what about the strings I’ve muted?

Once I’ve finished tuning the last note, I usually go back to the top octave unisons and remove the strip mute from just one string, leaving the untuned string open as well as the string next to it I have already tuned. I tune the untuned string to the tuned string by ear. This is why it is critical to have a quiet workspace—because we have to listen every closely to make sure they are exactly in tune with each other so that you can’t tell two strings are being struck instead of just one. It takes a lot of brain power to concentrate on this part, especially at the highest notes on piano.

I go one by one up the piano. For three-string unisons, I will have tuned the middle string in my initial pass-through, so moving from left to right up the piano, I tune the left string of the unison to the middle string, and then the right string to the other two strings.

As you can imagine, it is a pretty tedious process, but once it’s done, I’m to happy to leave you with a tuned piano. Growing up, I would never ask for birthday presents, or any gifts for the holidays, instead I would just ask to have the piano tuned, so I know how important a tuning is for players and I take such pride in completing a tuning.

If you have any questions about this process, please feel free to reach out! I love talking about it, and it even helps me to know what I haven’t explained clearly.

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