NBC Learn: The Science of a Steinway Piano

June 1, 2017

NEW YORK (NBC LEARN K-12) - At the Steinway & Sons factory, in Queens, NY, artisans build some of the finest pianos in the world. Every piece of a piano, from its case, to its cast iron brace, to its soundboard and strings, plays an important role in creating a piano's octaves of sound. This story is produced by NBC Learn in partnership with Pearson.



BOB BERGER, Director of Customer Satisfaction, Steinway & Sons: One thing that many people don't realize is the hand-crafted acoustic piano that we make is really a very highly engineered product. The piano has up to 236 strings on it. And the cumulative force of the strings on the case is tremendous. It can reach up to above 30,000 pounds of force.

My name is Bob Berger. I'm director of customer satisfaction here at Steinway & Sons in New York City.

The cast iron plate, which is the gold harp, if you will, that's inside every grand piano, is fastened into the case, and that cast iron plate, in combination with a hard rock maple laminated rim, is able to control that great amount of force and remain stable.

The stringing of the piano occurs once the case has been constructed, and, most importantly, the sound board and the bridge have been installed. At that point the piano and the sound board are ready to accept a downward force from the strings.

At the stringing operation, note by note is strung with steel wire. It begins on one end and goes across, primarily the treble wire. That's all the steel wire that you see. And then in the bass section the wire looks different. It's thicker, and it looks copper colored. The bass section is above the steel strings. That's called cross-stringing. This allows us to have longer bass strings in a shorter case.

When you play a middle C, a hammer is striking a string of a defined length, of a defined diameter, of a defined tension, and of a defined density.  From a theoretical standpoint, if you were to cut that string length in half, and you kept the tension the same, that would no longer be the same pitch. It would be an octave above the note you just played. Conversely, if you take that string length and you were to double it and keep the tension the same, the pitch would be a perfect octave lower, and so on, as you go up and down the scale.

Now, practically speaking, this is not possible, because if we had one wire size, we would need a piano that would be - when it gets down to the bass end, probably 20 or 25 feet long.  So that's compensated for by Steinway by increasing the diameter and the mass of the string. That allows us to keep the wire short enough to fit within the case of the piano.

Once the piano is strung it has to go through a number of more operations before it's complete. The next, significant stage would be the installation of the keyboard and the action, and how that is regulated or adjusted. Also what follows is the installation of the damper system.  Once that is put in place and that has been built out, the pianos now begin a tuning process and a voicing process.

BRUCE CAMPBELL, Tone Department: The notes that I marked with the chalk are a little bit louder than I’d like. And what I’m going to have to do is even it out a little bit. And what I do is I actually take the needles and my voicing tool and soften up the felt of the hammer, a little at a time. And I can create even tone throughout the instrument.

BERGER: Specifically the sound board and the felt in the hammers itself have physical properties that are natural.  This is wood and felt.  And they have some of their own nuances that are beyond our control that contribute to the personalities of individual Steinway pianos that people will often talk about.

There's a great deal of mathematical theory that goes into the scale design, and takes a long period of time to work out.  But also, there are some more difficult things to get our arms around that are contributions from the different materials that are used in the piano. 

CAMPBELL: I grew up with a piano in my house. And I taught myself how to play. So I love the piano, the most beautiful instrument ever created. 

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