The Origins & Construction of the Piano

In this lesson, we will discuss the origins of the piano and how the instrument works. 

Piano Construction

Pianos are made up of a few main parts: the keyboard, action, strings, soundboard, and frame. 

• The Keyboard: Home to all 88 keys of the piano. It's main function is to initiate the action (drop a hammer onto the strings) when a force (by your fingers) is applied. 

• The Action: This refers to the sequence of events that occur when you press down on a piano key. Essentially, when the keys are pressed, a hammer inside the piano falls onto strings. However, this alone does NOT cause the piano sound you are used to hearing. It's only a part of the process that creates that sound. The action is the most complicated part of a piano and is discussed more in the next section. 

• The Strings: Many believe this is the main source of sound in a piano, but that is not necessarily true. Pianos can have anywhere from 226 - 243 strings depending on the size of the instrument. The strings (made of steel) can be as long as 2 meters for the lower (bass) notes and as short as 5 centimeters for the higher notes. 

  • • Fun fact: The tension needed in piano strings can be as high as 220lbs for concert grands. This is so that pianos can be played at high volume levels. 

• The Soundboard: This is the true source of radiated sound from a piano. It merely amplifies the sound that comes from the hammers hitting the strings when a key is struck. This happens similar to a Domino Effect or you can envision a Rube Goldberg Machine. The soundboard vibrates once the string(s) are struck causing the sound of a piano people enjoy. 

• The Frame: This is the wooden casing (often spruce wood). It serves to protect the inner workings of a piano from contaminants (i.e. dust, excess moisture, bugs, etc.). It also serves to project the sound waves from a piano outwards. 

The diagram below provides a labeled visual of what these parts look like and where they are located. Notice that the keys on this piano have been pulled out to expose the hammers and the action. 

Piano Keys Construction & Action

So, we have established previously the basics of what happens when a key is pressed down. A hammer falls and the soundboard vibrates to create sound, but you can see the image below and tell that there's much more to the story. This is called the action. Below are the steps to the action of every piano. Look at the diagram as you are reading the steps. This happens every time you press a key on a piano. 

1. The key is pressed

2. The capstan will rotate the whippen

3. The whippen will force the jack against the hammer

4. The hammer then starts to make its way towards the string

5. Just before the hammer hits the string, the lower end of the jack hits the regulator 

6. The jack rotates away from the knuckle

7. The hammer (still in motion from step 4) hits the string

8. The back check stops the hammer from continuously hitting the string due to rebound force

9. Once the key is released, all parts return to their original position so the note can be repeated

Watch the video below to see the action (no pun intended :) .

The Three Pedals

Pianos have a series of 3 pedals that are used to manipulate the sounds that come out of the soundboard. These 3 pedals can be considered as part of the action. The pedals on pianos were not implemented until the 19th century, but the earlier models still had a form of a pedal. Instead of using their foot to press a pedal, pianist used their knees to press a lever. This was called a knee lever. Below are the names of all three of the piano pedals and their purpose. Refer to the image below as you read. 

• Sustain Pedal: This is the most commonly used pedal. For electronic instruments, this is usually the only pedal that is used. It is also called the damper pedal. This pedal raises the dampers in the action of the keys to allow the strings to continue vibrating after being struck by the hammer. The sustain pedal allows any music played on the piano to have what musicians call flow or legato (smooth) sound. 

• Sostenuto Pedal: This pedal is also called the practice pedal and it is used just for that purpose. When pressed, it lowers a piece of felt from the hammers onto the strings to muffle the sound making it quieter. 

• Una Corda Pedal: This pedal moves the hammers closer to the strings often shifting all the keys to the right. On grand pianos, it causes the hammers to hit fewer strings (there are often multiple strings tied to one note) to lighten the sound. On upright pianos, the pedal causes the hammers to fall slightly downward to decrease the distance it has to fall on the strings. This in turn lightens the sound. 

Tuning Pianos

If you look back up at the Grand Piano image, you may notice something called a pin. A pin (aka tuning pin) is used to tighten and loosen the strings. Much like playing a rubber band guitar, a tighter string will result in a higher pitch and a loose string will result in a lower pitch. Pianos are typically tuned to what is called the Railsback Curve as seen below. The graph shows the Railsback tuning (what we might call a perfectly in tune note) compared to the piano tuning of an expert tuner. The expert tuner looks to be off by quite a large margin, but the deviations actually are not that noticeable. 

The graph shows the Railsback tuning (what we might call a perfectly in tune note) compared to the piano tuning of an expert tuner. The expert tuner looks to be off by quite a large margin, but the deviations actually are not that noticeable. Based upon the graph, piano technicians have found that pianos sound best tuned to a note A440. This means that the note A above middle C is tuned to 440Hz. Tuners then use other methods to tune all the other notes around A440. 

To define some vocabulary: 

• An octave is an interval between one pitch and another with exactly double the frequency. For example, the note A above has a fundamental frequency of 440Hz. An octave above this A would have a frequency of 880Hz. 

• A cent is a unit used by piano technicians (or tuners) to measure pitch/frequency levels to properly tune pianos. Most commonly, frequencies are measured in Hertz (Hz), but cents are sometimes used instead. One Hertz is equal to about 4 cents. Cents have more of a musical significance when it comes to tuning and can be related back to music theory. There is quite a bit of math behind tuning pianos, but we will not get into that. 

Much of the tuning done on pianos today is done electronically, but these electronic programs are based upon these principles and data obtained from acoustical physics methods. 

Tuning pianos is no easy task and should be done by a professional at least once every 6 months.

Piano Maintenance

If you own any piano or keyboard, you should know how to properly maintain it and care for it. Below are a few tips I have found (from Steinway & Sons) and recommend to you to care for your instrument. Repairs on a piano can cost as much if not more than car repairs, but pianos are much easier to care for than a car. 

 Grand/Upright Pianos

• Keep your piano in a room that is kept at around 68 degrees Fahrenheit and at a humidity of 45-70%. Humidifiers should be kept in the piano space to avoid huge jumps in humidity. This can damage the wood. 

• Pianos should not be placed close to a window or anywhere else it can be exposed to high levels of heat. 

• If you have a newer piano (less than 1 year old), it is recommended that you tune it more frequently (more than twice) as the parts inside are still settling. Afterwards, tune twice per year (or every 6 months is ideal). 

• Service your piano every 3-5 years. If used for gigging purposes, a service should be done every year. 

• Only clean the surface of your piano with a soft dry piece of cloth. DO NOT use any type of furniture polish. The keys can also be cleaned with a piece of dry cloth. 

• Use casters to allow for easy moving of your piano. 

• Do not smash down or lean on the keys. Heavy forces on the keys will cause damage. 

Keyboard Pianos

• Keyboards are much easier to care for than grands or uprights. Keyboards do not require servicing unless something is damaged. A good rule of thumb to follow is to just keep the frame and keys clean and avoid doing anything that could damage the inner components of the instrument (i.e. playing too hard, heat exposure, dropping the keyboard, etc.). 

• Keyboards do not necessarily need to be kept in a room with a certain temperature or humidity as they are mostly made of high quality plastics. 

References

• Thomas Rossing, Paul Wheeler, and Richard Moore, The Science of Sound, 3rd ed. (Pearson, 2014). 

  • Information and other images from this lesson were pulled from Chapter 14: Keyboard Instruments, sections 14.1 - 14.6. 

• “Service & Maintenance.” Steinway & Sons. Accessed February 23, 2023. https://www.steinway.com/news/features/utilty/service-and-maintenance#15716997-6952-47a9-a4e4-63f7a8732b8f.