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Writer's pictureRyan Robertson

Why Do Pianos Go Out of Tune?

Updated: Jul 3, 2020




When I was growing up and studying music, I could never resist playing a piano that was nearby. To this day, even if it is just touching a few notes, I always walk over and visit the piano unless it is inappropriate to do so and even then, it takes discipline for me not to. Sometimes the visits are much longer than a few notes and this usually depends on how in tune the piano is. Of course, other factors like the responsiveness of the touch or having an enthusiastic listener could extend the time spent at the piano but nothing will cut it short faster than a sour, out of tune sound when I play that first chord. Have you ever wondered why pianos go out of tune? All pianos will go out tune if not maintained and here is why:


Seasonal Humidity Changes.

Sure, the house feels great in the spring when you throw the windows open and welcome the refreshing outside air into your home. This is one of my favorite times of year however, this is a major cause of pitch fluctuations in pianos. The air in springtime is very moist, and this is going to affect the air inside your home or studio differently depending on the type of structure. As Summer moves in the humidity continues to rise since hotter air can hold more moisture. So what does this mean exactly for the piano? It means that the wooden components of the cabinet and action are going to swell up. Not like a bee sting on your cheek, but enough to put pressure on the strings and push the pitch of the piano higher. This is especially a problem in the middle area of the keyboard. No one ever plays in the middle of the keyboard, right? Yeah.. wrong. This will cause the extreme ends of the keyboard to sound too low and while this doesn’t sound too bad in the bass section, it is very noticable in the treble section. As you might then expect, pianos go flat in Winter months when owners run their furnace which dries out the air and reverses the swelling that puts pressure on your piano’s strings. ​ A dry environment is not bad for a piano but there are some harmful effects of extreme dryness (>20% relative humidity) on the delicate wooden parts of the instrument including cracks in the soundboard or bridges and also unfavorable changes to the touch and action since the small distances between wooden and felt components will increase beyond the ideal range. This can cause noise in the keys or action, a disconnected feel and can even cause lost grip of the tuning pins in the pin-block. Yikes!


Green Strings.

Believe it or not, piano strings which are made of steel or a mixture of copper and steel are very elastic and will continuously stretch throughout their service life. A piano that is brand new or less than a few years old has strings that are “green” meaning they are still stretching out and can go flat more quickly. For this reason, it is important to have the piano tuned at least every six months to a year until the strings stabilize, after which you can get by with every 1-2 years with proper care. This also applies to broken strings that have been replaced with new wire on older pianos. It is common for tuners to get called back to touch up recently replaced strings.


Slipping Tuning Pins.

As I mentioned earlier, the holes in the wooden pin block can enlarge and lose their grip around the tuning pins. Fortunately, this rarely occurs in newer pianos. Eventually however, after decades of pressure and seasonal changes, the holes in which the pins are driven will expand. When enough grip is lost, the tension of the strings will cause the tuning pin to twist allowing the coil to unwind and the pitch will go flat. I have encountered pins while tuning that were so loose that the pin would unwind sending the tuning hammer, which was still on the pin, swinging back to the left as soon as I let go!


Heavy Playing.

If you play or practice frequently (which you should!) or do a great deal of loud playing then you will knock the strings out of tune over time. Playing by itself doesn’t cause a huge change in string tension but it does release some of the slack caused by other things we’ve already talked about. This slack is stored in non-speaking portions of the string and is allowed into the speaking portion when the string is struck. Pianos used for big concerts or long recording sessions are tuned or at least touched-up as frequently as every 30 minutes!


So How Often Should I Have it Tuned?

For the average home piano, every six months is more than ideal and you can get by for longer with certain practices which I will discuss next. There is no exact answer for this question but the factors discussed above can give you a better idea of where your pianos needs likely fall. Here in Texas where the weather is all over the place, pianos tend to need more frequent tunings but in a place like Los Angeles with more a consistent climate it is easier to go without for longer.


What Can I Do to Help My Piano Stay in Tune Longer?

The simplest way is to have it tuned more often. While this may seem like a no-brainer, consider that some pianos have to be tuned two or three times in a row after years of not being tuned increasing the cost of the service, especially on a newly made piano. Beyond this, the best way to stabilize the pitch of your piano is to create a stable environment for it. This could mean managing the relative humidity level in your home or having a climate control system like the Dampp Chaser system installed in your piano.


Why Do Some Pianos “Hold Tune” Better than Others?

The quality of the wood, glue, steel, and methods used in the crafting of the piano certainly play a major role in tuning stability. Steinway’s “hexagrip” pin block uses alternating grain patterns between layers (all pin blocks use laminate wood, not solid wood) of maple to increase grip while maintaining a smooth feel for the tuner which allows them to make more precise adjustments. Additionally, not all soundboards are equal and piano makers look for wood species that have the perfect combination of stiffness, elasticity and resonance. Sitka spruce is probably the most popular type of soundboard used which is lighter than other woods of similar strength. When buying a piano, you can expect the more expensive models to boast better soundboards and pin blocks which will reward you with better tone and stability however, no piano nor its components are immune to the environmental effects discussed above. Regardless of what piano you own, you will get the most enjoyment out of it through regular tuning and a stable climate.


Its Been Years Since Last Tuning But My Piano Still Sounds Good. Can I Wait to Tune It?

Sometimes the answer is yes, but many times pianos have gone flat while retaining the proper relationship from note to note allowing the piano to sound in tune with itself. This may meet your playing needs but it still should be tuned back to concert pitch to sound its best since all piano makers design their “scale” to be tuned to this tension level. In terms of construction, the scale of a piano is a combination of the overall length/height of the piano and the progression of string lengths and thicknesses from the lowest note to the highest. Lower tension that intended can cause undesirable overtones to become prominent and the piano to sound impure. If you are unsure, ask your tuner for a pitch check, or get ahold of a chromatic tuning device or use a tuner app on your phone to check your piano. If the tuner is automatic you can just play any note and it will pick it up and tell you how flat or sharp it is. If it is not automatic you will need to make sure it is set to match the note you are playing but most devices and apps are. If it is more than 10 cents low, it is definitely time for a tuning!


I hope this article has given you some insight on maintaining the pitch and tone of your piano. A well-tuned instrument of any kind is vital to enjoying the music it produces and also provides a more inspiring experience. One of my favorite things to do on piano or guitar is improvise melodies, chord-progressions or both and without fail I come up with better ideas when it is in tune.

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