Why do some pianos stay in tune longer than others?
New pianos will not stay in tune very long because the strings are stretching so much. A piano that has had numerous tuning over a 10-year period frequently stabilizes the tension on the cast-iron plate and remains in tune amazingly well. Some small pianos that do not have much support in the back structure never stay in tune well. If a piano is situated in a stable environment, no drafts, no hot air vents, no open windows, no direct sun, it can remain in tune for long periods of time.
