How the Piano Works
The piano's early design was determined by the design of other keyboard instruments of the time, such as the harpsichord. Apart from a few offshoots like the square piano, the modern piano has retained this basic appearance throughout the years. Today, the piano is seen in two basic forms, the upright and the grand. The difference between the two is simply the arrangement of the soundboard in relation to the keys, with the upright it is perpendicular and with the grand it is parallel. Otherwise, the acoustic principles and mechanics are the same.
Simply put, the piano's sound is produced by strings vibrating across a soundboard. The process works something like this:
The piano action
Grand Piano Action
Upright Piano Action
When a key is pressed down the opposite end rises and sets the piano action in motion. The action is a very complex arrangement of parts that allows the player to control the force and repetition of notes. After the action does its mechanical magic it sets a felt covered hammer in motion, which then strikes a string.
The strings and plate
The strings are stretched across the length of the soundboard under great tension. However, they don't actually rest against the soundboard because the tremendous amount of tension would warp and bend the wood. Instead an iron plate, which is secured to the piano's frame, rests between the soundboard and strings and withstands the string tension. One end of each string is connected to a tuning pin, which is drilled into a pinblock. The string then stretches down to a hitch pin, which is a hook at the other end of the plate. Finally, the string returns to the pinblock and is connected to another tuning pin.
The soundboard and bridges
The soundboard is usually made of some type of spruce, which has very tight grain patterns that transmit the sound very well. It is essentially a large membrane that receives the string vibrations and amplifies them, much like a speaker does. There are also two bridges, one for the bass strings and one for the treble strings, that are attached to the soundboard. It is against these bridges that the strings actually rest. So, the string vibrations travel through the bridges and then into the soundbaord.
Grand Diagram 1
Grand Diagram 2
Upright Diagram 1
Upright Diagram 2
The Piano's Range and Tuning
With 88 keys, the piano's range is impressive. However, with such a large range tuning becomes difficult. In order to keep the musical intervals even across the entire range of the instrument a tuning system called equal temperament was developed. With equal temperament, each octave is "stretched" slightly beyond their absolute pitch values. This is necessary because of the inherent inharmonicity that exists with all pianos. The effect is a piano that isn't tuned precisely according to theoretical pitch values, but one that can be played alongside other instruments and that sounds in tune across its entire range.
The Earliest Pianos - The 18th Century
All inventions have their antecedents and the piano is no exception. Numerous keyboard instruments had existed for quite some time before the piano entered the musical scene. The piano's creation was borne out of a desire to improve upon these instruments. The creative urge revolved around the need for an instrument that would combine the expressive qualities of the clavichord while maintaining the sonority and volume of the harpsichord. Many instrument makers had been working on this problem in the late 17th and early 18th centuries, but it was Bartolomeo Cristofori, an instrument maker and caretaker for the Medici court in Florence, who is credited with the first workable design. The exact date and initial number of Cristofori's "pianofortes" is unknown, but most cite the written record of Scipione Maffei in 1709, which referred to Cristofori's four "gravicembali col piano e forte" or harpsichord with soft and loud. Hence the name pianoforte, which was later shortened to piano.
So, the first pianoforte appeared at some time during the first decade of the 18th century. It resembled the harpsichord in design and function except for the action, which is what set the new instrument apart. Cristofori's pianoforte employed small hammers, covered in leather, to strike the string as opposed to the plectra of the harpsichord, which plucked the string. Additionally, the new action integrated an escapement device, which allowed the hammers to be released from contact with the back of the keys once set in motion and to rebound from the strings after striking them. This gave the player more expressive control over the volume and dynamic gradations, which was previously nonexistant in any single keyboard instrument. Cristofori also included a means to shift the entire action slightly to one side, which caused the hammers to strike only one of each note's two strings, thus lessening the volume. This was the forerunner of the una corda pedal that is incorporated into all modern pianos. However, his pianoforte had a very weak volume due to the thin strings and hard hammer material. Cristofori's new invention was generally regarded as a novelty instrument and did not make an impact upon composers or the music public. It remained for German keyboard makers to usher a lasting change.
Gottfried Silbermann, a German instrument maker who was most likely introduced to Cristofori's invention via a German translation of Maffei's account, produced his own pianoforte in the 1730's. It was reportedly presented to Johann Sebastian Bach for inspection, who gave it an adverse review due to its heavy action and a weakness in the treble register. Silbermann then made some improvements, to which the immortal composer gave his seal of approval in 1747. A number of these pianofortes where purchased by Frederick the Great, of which two survive. The actions of these two Silbermann models are identical to those of the three surviving Cristofori pianofortes. It seems that Silbermann recognized the genius of Cristofori's conception and chose to maintain rather than alter it. However, one feature was added by Silbermann: the use of stops to lift the dampers off of the strings, allowing them to vibrate freely. This gave the pianist another means of expressive conrol and was the precursor to the sustain pedal that was added to all later pianos. Further experimentation by german keyboard makers, including a few of Silbermann's apprentices, took place throughout Germany during the mid 18th century. However, most of these turned out to be evolutionary dead ends.
The English and Viennese Piano Schools
The next step in the development of the modern piano takes us to London, to which a small group of instrument makers had migrated from the German duchy of Saxony around 1760. This group has been dubbed the 'twelve apostles' in reference to their carrying of the pianoforte idea abroad and ushering in the beginning of its popular success. One of these men and a former apprentice of Silbermann was Johann Christoph Zumpe, who created and successfully marketed his 'square pianos'. These square pianos were oblong shaped instruments and became the popular alternative to the original wing-shaped piano design. Beginning in the 1770's the square pianos were improved upon by John Broadwood. It was around this time that the "grand" became a designation for the original piano design to differentiate it from the growing numbers of square pianos. Broadwood's innovations were also directed towards the grand pianos. He extended the piano's range on both the treble and bass ends, increased the string tensions throughout, and altered the speaking length of the strings. All of these improvements gave the instrument a heavy tone with greater sonority and volume. But, these improvements also necessitated alterations in the action, and his changes gave rise the heavy "English action". Concurrent developments in Germany and Austria gave rise to what was known as the Vienna school of piano making. These pianos owe much to the work of J.A. Stein, who developed pianos with a lighter build and a nimble and bright tone.
The Piano Comes into its Own - The 19th Century
Increased use of the piano by composers such as CPE Bach, Muzio Clementi, Mozart, and Beethoven gave it a respected place in the musical world. However, the innovations of these composers called for a stronger and more sonorous tone, which brought about further improvements for the piano. This typically resulted in heavy strings under greater tension, which in turn required more a robust construction and responsive action. The introduction of bichord and trichord stringing (whereby the hammers strike two or three strings together to produce a note) also improved the piano's tone and volume, but greatly increased the tension and tuning instuability. In order to stabilize the instrument's tuning stability and keep the wood from buckling under the tension an iron plate was incorporated into the design. It was sandwiched between the soundboard and plate and has remained an integral part of the piano ever since. Additionally, the soundboard was made thicker to give it a more powerful tone and to withstand the downbearing of the string tension.
Larger and softer hammers were introduced in the action, which gave a fuller and rounder tone to the piano. The action's escapement mechanism was also improved upon, allowing faster repetition of notes. A final innovation was added in the mid 19th century - overstringing. Previously, all strings ran parallel across the soundboard. However, to get a more powerful bass tone the bass strings need to be longer. This seemed to require and inordinately long piano. Overstringing solved this problem by stretching the strings over the treble strings, thereby increasing their length without inscreasing the size of the instrument. It was overstringing that allowed the upright to virtually replace the square piano and remain a viable alternative to the grand.
Although the square piano had enjoyed immense popularity as a home instrument, by the late 19th century it had become obselete and virtually dissappeared. It's main limitation was the limitation on it's string length and thus its sonority and tone. The upright served as it's replacement for a space-saving instrument. Upright designs had been around since the eighteenth century, but it wasn't until the mid nineteenth century that the upright became widely accepted. The upright action has always suffered from a drawback in that gravity does not give much assistance to returning the hammers to their resting point quickly. This of course affects repetition and nuanced control of the keyboard. However, numerous improvements made the upright action more responsive, though it will never be as responsive as well as the grand action.
So, by mid 19th century the piano had evolved into the basic design we see today. Although there existed two distinct schools of thought in the early years of piano development they slowly converged to produce the modern piano. Today, and for the past century, most piano manufacturers adhere to the same general design principles that grew out of the nineteenth century. Innovations and unique developments are often confined to altering minor parts, choice of materials and wood, and changing the ever-adaptable stringing scale arrangement.
20th Century Piano Trends
Although pianos remain popular and familiar with audiences and players, their prominence has waned a great deal since WWII. In the 19th and early 20th centuries owning a piano was seen as a mark of respectability and something that many families strived for. Furthermore, actual instruments were typically the only means of musical entertainment available prior to the 20th century. With the advent of audio recording technology the piano's preeminence naturally declined. Although the association of pianos and respectability still holds true today, it is not nearly as prominent. This is in part due to the fact that there are so many other high-ticket items and objects that people can fill their homes with. Electronic and digital variations of pianos are typically much cheaper and take up less space than an acoustic piano. However, even with these changes the piano still retains its unique characteristics and will most likely remain with us for some time.
Piano
Grand Piano Action
Upright Piano Action
Grand Diagram 1
Grand Diagram 2
Upright Diagram 1
Upright Diagram 2
