Piano Tuning Stability

Eterna ER-10 made by YamahaI bought a small little used Yamaha made piano about 6 months ago. The Eterna ER-10 is a well built, inexpensive piano which was manufactured in Japan in the 90’s. The previous owners hadn’t had the piano tuned in over 10 years. The piano was a quarter tone flat, which isn’t that terrible considering the fact it hadn’t been tuned in such a long time. Once I got the piano in my house I proceeded to give the piano a pitch raise. It is often recommended to let the piano sit and accustom to the new humidity level for a couple days before tuning. The piano, which was a quarter tone flat, was enough out of tune that it wasn’t going to make much of a difference whether I tuned it immediately or whether I waited. Besides, a pitch raise is merely a rough tuning to get the piano up to an approximate pitch of A=440Hz. I gave the piano the pitch raise and then let it sit for a couple days.

I gave the piano a good solid tuning a few days later which lasted about a month. Certain unisons began to go out and the overall pitch had fallen a couple of cents in that month. A cent is 1/100th of a semitone which on the whole wouldn’t be that noticeable to the average ear, while the unisons being out would be noticeable. I put another solid tuning on the piano which lasted another month before the summer humidity began to kick in and the piano’s pitch moved sharp, as well, unisons had audibly gone out of tune with themselves, though there were fewer then the previous time. I proceeded to tune the piano again, this time leaving the piano a couple cents sharp. I did this knowing that come fall, the piano will move back down to proper pitch.

The audible sign of tuning instability is unisons going out of tune. On each treble note there are three strings. When they go out of tune with each other you will notice a sometimes audible whine or warble. The unisons on my piano have been stable since that last tuning and it has been longer then a month. When a piano hasn’t been tuned in a number of years, the piano loses it’s tuning stability. The wooden soundboard and bridge become accustomed to the tension exerted by the strings which may be flat by a quarter tone or more. When they are forced back up to their proper tension being A=440Hz a resulting instability is created. The wood is fighting the new tension as well as the steel string. When I do a pitch raise on a piano, I leave the piano perfectly tuned, though in the coming weeks the piano will try to adjust to its new tension and unisons will undoubtedly go out.


A piano which has had its tuning neglected over a number of years may take 3-5 tunings to regain its tuning stability. Keep your piano tuned regularly at least once a year and you will enjoy a tuning that is more stable and lasts longer.

2 replies on “Piano Tuning Stability”

Thanks for this article. I am new at piano tuning. Since this is a part-time job for me, I am not trying to steal customers from tuners that depend on established customers for their living. Most of my customers haven’t had their piano tuned in 10-40 years or more. Needless to say, I am doing pitch-raises on most of the pianos. Some people want me to leave it flat, as long as it is in tune with itself. Your article will help me explain that neglected pianos will not stay in tune for a long time. I hope you don’t mind if I link to your site on my Facebook page, or refer people to it for education.


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