Apple Valley Guitar and Piano Academy
The Inside Story of the Piano
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The soul of the piano is its soundboard, a large, thin piece of wood (usually spruce). The bridge, a long curved strip of wood about 1 inch high capped with a thin metal strip, is glued to the far end of the soundboard.
The strings (metal wires) are in forcible contact with, and pass over, the bridge. Beyond the bridge, the strings are attached to a cast-iron plate by short, angled metal hitch pins. The plate withstands the 1000s of pounds of pressure of the tightened strings for all the piano's notes.
Near the front of a grand piano, the strings are attached to screw-like metal tuning pins. They are about 2-1/2 inches long, about the same diameter as a pencil, and emerge through holes in the end of the plate nearest the keyboard. On a grand piano, you can see the pins if you move the music desk backwards and away from the keyboard.
The pins are driven into a densely layered, cross-grained piece of wood called the pin block. The pin block must be of high quality to ensure that when a piano tuner moves the pins right or left to adjust the pitch, they stay put for a reasonable length of time. Otherwise, the piano will go out of tune quickly.
When a white or black key is pressed, felt-covered hammers strike the strings for that key, and the bridge transmits the string vibrations to the soundboard.
In order to get an excellent tone from a piano, the soundboard must be made from solid wood. In less-expensive types of pianos, such as entry-level uprights or grands, the soundboard may be laminated by gluing together several layers of wood. This makes the soundboard less responsive to the vibrations of the strings. The result is poor tone and a narrow range of volume compared to a solid-wood soundboard.
There are three classes of strings per note/key in a grand piano: 1 string for the lowest bass notes, 2 strings for higher bass or tenor notes, and 3 strings for midrange and treble notes. Groups of 2-3 strings for a particular key are called unisons, because they must both be tuned to the same pitch.
The action is a complex assemblage of wood, metal, plastic and leather parts that make the hammer strike the strings when a key is pressed.
Click here for an animated diagram of a grand piano action
Click here for diagram A of a grand piano action
Click here for a diagram B of a grand piano action
Beyond merely sounding notes, the action allows the pianist to control the volume and tone of notes. Thus, it must be well constructed if a pianist wants to play accurately, musically and expressively.
Grand pianos have a special "double escapement" feature that makes more rapid repetition of a single key possible.
The dampers are sections of wood with felt-covered bottoms that fall onto the strings when a key is released. As a result, the sound of the note is silenced.
The damper or "loud" pedal prevents the felt dampers from falling onto any of the strings, so the strings are free to vibrate. Therefore, with this pedal engaged, and a key is pressed and released, you can still hear the note. Also, other un-played, un-dampered strings in the piano resonate along with the note to produce a rich, colorful sound with much greater sustain. The sound is also airy and reverberant.
The una corda ("one string") or "soft pedal" causes the entire keyboard of a grand piano to shift slightly to the right. As a result, hammers that normally strike three strings strike only two; hammers that strike two strings strike only one, and hammers that strike one thick bass string hit the string off-center. The main goal is to change the tone of a grand piano, primarily due to the fact that fresher, less compacted felt is striking the strings. The fact that fewer strings are struck also reduces volume, hence the name "soft pedal".
The middle pedal on three-pedal pianos is called "sostenuto". If one or more keys are played and this pedal is immediately depressed, when the fingers release these keys, the notes continue to sustain as long as the pedal stays down. Other keys played later, however, are not sustained, and are dampered/muted as soon as their keys are released.
Click here to read our head teacher's article "How to Use the Piano Pedals".
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