Pianos with Tuning Stability Problems, the Causes and What to Do About It

I see pianos of all types, sizes, shapes, colors, old, new, pristine, beat-up, you name it. Some hold their tuning freakishly well between visits. I am always amazed by this. While other pianos can’t seem to stay in tune even during the course of my tuning visit. Why the vast discrepancy in tuning stability from one piano to another? Well, as you can imagine, there are a whole host of variables to contend with.

For the sake of efficiency in understanding this phenomena, I would like to break it down into three main categories which contribute to tuning instability:

1) Piano Condition
2) Piano Quality (Or Lack Thereof)
3) Humidity Conditions

Let us explore each category:

Piano Condition

The structural condition of the piano greatly contributes to a piano’s tuning stability (or instability). A bad pinblock is a major contributor to tuning instability. The pinblock is a multi-layered plank of wood which holds the tuning pins. Over the years the layers can delaminate, crack and disintegrate which can lead to loose tuning pins. Generally speaking, the greater the torque of the tuning pins the greater the tuning stability. We want resistance. Sometimes things can get so bad that one note can actually sound like two notes. And some notes cannot be tuned to the proper pitch at all.

Piano Quality

A good quality piano can last 50 years or more, after which point a lot more maintenance other than tuning is required to keep the instrument in working order. A poor quality piano will not wear well over time. Structural instability can accelerate at a pace exceeding that which is normal. A poor quality, cheap soundboard can lead to tuning instability. Sometimes the wood of the instrument is not cured properly at the factory. This can also cause tuning instability problems down the road.

Humidity Conditions

Seasonal humidity changes are significant in New Jersey, the dry season of the winter transitioning to humid season of the summer, can upset tuning stability. The soundboard of the piano flexes with the humidity changes, pushing the bridges up or down which can knock the piano out of tune. Typically, pianos go flat in the winter as the soundboard contracts in the dry season and go sharp in the summer as the soundboard expands w/the humidity. Normal pitch drift is about a 1/10th of a tone or less, sharp or flat from A-440 hz concert pitch.

Different Remedies and How I Troubleshoot:

1) New Pinblock Installation
2) CA Glue Pinblock Treatment
3) Dampp Chaser Humidity Control System

New Pinblock Installation

Individual notes can have more than one string. Plain wire strings typically have three strings per note tuned to same pitch. We call these strings unisons. Copper wound bass strings typically have two strings per note which graduates to one string in the low bass.

If I hear individual unisons that are way out in relation to their neighboring strings or notes that are way below their desired pitch in relation to the other notes in the tuning scale, these are all red flags for a bad pinblock. Replacing a pinblock is the most costly of all the options, yet it is the most lasting and permanent repair. For high quality pianos like Steinways and Bosendorfers, or for pianos that have sentimental value replacing the pinblock may be worth your while.

CA Glue Pinblock Treatment

For lesser quality pianos it may be more desirable to do a CA glue treatment of wicking thin CA glue around the tuning pins to seep into the cracks of the pinblock to give the tuning pins more torque. This can give you another 10 years or so out of the block and is FAR less costly than replacing a pinblock outright.

Dampp Chaser Humidity Control System

As previously stated 1/10th of a tone or less drift sharp or flat between seasons is normal. If the drift is excessive, say 1/4 tone or 1/2 tone, then that is indicative of poor humidity conditions in the space.

Also if the scaling of the piano is inconsistent then that is another red flag. What do we mean by scaling? A-440 hz is the international concert pitch standard. That is what we tune to. If the bass section is around A-440, the middle section A-435hz (a lower pitch) and the upper third even lower than that then “Houston, we have a problem with our relative humidity levels!”

Optimal relative humidity between 45 and 60% is optimal. If we go outside this window this can lead to inconsistent scaling. A Dampp Chaser humidity control system or room humidifier is the best solution if these indicators are present. A Dampp Chaser system has a humidifier, de-humidifying rods and a humidistat (which is the brains of the system that controls when to humidify and when to dehumidify). A Dampp Chaser system is installed under the piano of a grand or inside the bottom board cavity of an upright. These systems are designed to keep the humidity level at the soundboard within the safe relative humidity window of 45-60% thus contributing to greater tuning stability. If the piano is in a smaller, contained space a room humidifier can also be an excellent, less expensive option. However, these units are only effective in smaller spaces as they would be next to useless in a church for example.

I know this blog post was long, but I hope you have found it informative. Happy playing!