Why Does Your Piano Go Out Of Tune?

This is a question I get a lot from my customers. Is it from the hammer hitting the string? Does it go out of tune because it's being played? Maybe because it's not being played enough. The good news is, no matter how you use your piano, it's not your fault that it's going out of tune. Let's explore why in some more detail.

To understand why a piano goes out of tune we have to delve into some technical information, but I'll keep it light. First, let's talk about what a piano technician does when they tune a piano.

Tuning a piano is all about the strings, the strings alone determine what pitch each note will produce. That pitch is determined by three characteristics of the string: length, weight, and tension. The length and weight of the string are parameters that can't, and frankly shouldn't, be changed. They're set in place by the engineer who designed the piano, and these professionals know what they're doing, so we should trust their judgement. That leaves us with tension, the thing the piano tuner can change.

If you open the lid of your upright piano, or look under the music desk of your grand piano, you'll see a sea of little silver pins. These are the tuning pins. Your technician will put their tuning hammer on these pins to adjust the tension of each string in a meticulous, iterative process. Tuning.

So we know how a piano is put in tune, but how does this inform how the piano goes out of tune? Barring major structural failure, the length and weight of the string cannot and will not change by itself. This is where tension comes in again, tension can change over time. If you follow the string from the tuning pin down the piano, you'll notice it makes contact with a long piece of wood which is fixed to the soundboard. This is called the bridge. Every string pushes down on that bridge with about 200 pounds of force, for a total of 30 tons of force on the entire soundboard. This is an immense amount of pressure!

Now we're getting to the reason your piano goes out of tune. You may notice that the soundboard of your piano is made out of wood. As the seasons change, especially here in New England, that wood will absorb and release moisture as the humidity in the air rises and falls. As a result the soundboard will change shape in a small, but measurable, way. When the soundboard changes shape, it increases or decreases the tension on the strings, changing their pitch.

So there it is, your piano goes out of tune because the weather changes. What can we do about that? More good news, there are steps you can take to keep your piano healthy and make your tunings last longer. The answer is climate control. A good first step before you spend any money on this endeavor is to assess where your piano is in your space. Is it near a window? Next to a heating or AC unit? Even an outside wall? These are all perilous places to put your piano. Often, the best place to put your piano is in the same neighborhood as your home's thermostat. This will promote stability. If your piano is on an inside wall, away from windows and HVAC units, but still going out of tune too fast, it's time to think about climate control.

Climate control doesn't necessitate home renovation, something as simple as a humidifier can do wonders for your instrument. One solution is to go to your local home goods or hardware store and pick up a humidifier. It's recommended to keep the climate around your piano consistently at 45% humidity. While 45% is important, the critical part of that statement is "consistently." No matter what humidity you keep your piano at, consistency is key. If humidity must be changed, do so gradually.

Another, more elegant solution is to have a Dampp Chaser installed in your piano. A Dampp Chaser is a combination humidifier/dehumidifier that regulates the climate inside your piano to keep your instrument healthy, and help tunings last. In general, I prefer Dampp Chasers for upright pianos, but I find humidifiers more effective for grands.

Even with all this, it is still recommended to have your piano serviced twice per year. It's good to have your technician take a look at your instrument often to keep it in shape. Remember, when you call for a tuning you should be getting more than just a tuning! Small repairs, regulation touchups, and light voicing are often part of a service visit.

So there you have it, keeping your piano in tune can be as easy as calling your technician twice per year and getting a humidifier from the hardware store.