What You Need To Know About A Piano Soundboard

The soundboard is one of the most important elements of a piano.  It is a large, thin wooden plate beneath the strings which acts as an amplifier, resonating with the frequency of a pianos vibrating strings.  Evaluating a piano’s soundboard consists of determining its structural integrity and its shape.  A newer and healthier soundboard should have plenty of crown, which is the slight rounding of the soundboard similar to that of a drumhead.  Having crown in the soundboard improves the tone, projection and sustain of the piano.

During the evaluation we measure the downbearing of the strings on the bridge which suggests crown in the soundboard. Any downbearing that reads .001 or higher is a good sign.  In the treble we would like to see between .015-.025.  However, it is important to note that an older piano may not have much crown or downbearing and that does NOT render it useless and of no value.  Many of these pianos are sill in use and very much enjoyed.  If you are considering a high quality and more expensive instrument a healthy amount of crown and downbearing is essential to be sure that the soundboard has plenty of life in it and will project the tone of the piano powerfully.

Pinblock Evaluation Process

The pinblock is another critical element of the piano. Located just above the piano’s keyboard, the pinblock is fitted and fastened to the permanently to the piano’s structure. This what is responsible for holding the string tension of the piano.  The tuning pins are hammered into the pinblock during the piano’s construction and then the strings are fastened to the tuning pins. 

Over time the holes drilled for the tuning pins may begin to enlarge and result in loose tuning pins. This means that during tuning the pin will not hold the tension required in the string and the tuning will not last as it should. Evaluating the pin block involves measuring the torque of the pin, which tells us how tight the tuning pins are. The torque is measured in inch pounds (in lb) and recording during the evaluation process.  

Steinway pianos will typically range between 40-100 in. lb.  If the numbers go much below 40 that is a sign that the pinblock will need to be replaced in order for the piano to be tuned and stay in tune.  Alternately some pianos can be restrung with the original pinblock, but using a larger sized tuning pin.

*Pianos with low pin torque numbers still have value, but our appraisals will reflect the fact that they do have less value than a comparable piano with adequate tuning pin torque.

Touch and tone scales

In an effort accurately as possible characterize the touch or tone of a piano we have created the scale you will see on the evaluation form.  Both scales are mostly self explanatory.  However it is important to understand how bright is bright, and how heavy is heavy, etc..

If a piano receives a tone rating of “bright”, indicated by a dot or circle around the bright end of the scale, that means that the piano has an extremely loud sound and hard attack.  On the other end, if the rating is all the way to the left over “mellow” that means that the piano is extremely quiet and the tone has a very soft attack.

The same goes for the touch scale.  “Light” and “heavy” represent the extremities of the piano action touch in terms of perceivable weight and measurable weight.