Action (piano)

[need quotation to verify] "A professional pianist is likely to care most about the piano's action, because that is what controls its responsiveness and relative lightness--or heaviness--of touch.

Roughly speaking, a piano's action is light when its keys fall easily under the fingers, and heavy when a noticeable downward thrust is required.

[5] Although similar hammer actions were devised at about the same time by Marius (1716) and Christoph Gottlieb Schröter (1717),[6]: 42  Cristofori was the only one of these three to actually construct an instrument.

[7]: 100  Alfred Dolge notes the first pianos were quite similar in construction to contemporary harpsichords, while incorporating key features of the clavichord, including the soundboard, metal strings, and percussive-string method of creating sounds.

Because of the stepped projection, the hopper slips off the key just before the hammer strikes the string, providing the escapement action.

Other modern features are apparent in his diagram, including the presence of a back check to facilitate repetition, and using the rising tip of the key-lever to lift the damper.

[7]: 101 Cristofori died in 1731 and left no significant pupils; the instruments that were in process were finished by Giovanni Ferrini, who also is credited with building a pianoforte dated to 1730.

[7]: 108  This "Viennese" action continued to be developed by Stein's daughter, Nannette Streicher, and was widely used by other makers in Vienna, and was the action of pianos played by Haydn, Mozart, and Beethoven, as it was characterized by a "pleasant light elastic touch and [a] charming musical quality of tone".

In the 19th century, the English action was further modified by French builders, notably in the invention of the repetition lever, which facilitated rapidly repeating notes.

Throughout the history of the action, piano makers tended to make it heavier and sturdier, in response to the increasing size, weight, and robustness of the instrument, which was itself part of a general demand for a more powerful sound.

Christian Ernst Friederici invented the first upright piano action in 1745, but it was not well-regarded;[6]: 91  Hipkins likened it to a Nuremburg clock.

[9] Keyboards that use moving weights similar to the motion of hammers without relying on springs are called hammer-action.

In addition, as long as the key is depressed, the action also lifts a felt damper off the appropriate string(s), sustaining the vibration.

[12] Traditionally, the individual parts of the action of an acoustic piano are made of wood with metal pins and pivots; some manufacturers have switched to using plastic and composite materials for certain items to add strength and environmental stability.

[13] Simultaneously, the rising end of the key also lifts the spoon (14), which is connected to a felt block called the damper (15), which normally rests on the string(s), preventing vibrations.

If the key remains depressed, the hammer is held above its initial resting position by the catcher (19), which rests on the back check (18), which is on the same (rising) side of the wippen as the jack; this facilitates rapid repetition of notes, although with a different feel than in a grand piano action.

[14] The Zumpe action, as fitted to his square pianos from c. 1765, is fairly straightforward: as the key (1) is depressed, the rising end of the lever raises the leather-covered jack (2), also known as the "old man's head".

This letoff button is attached to the hopper, which is hinged and held in place normally by the spring slide wire (15).

If the key remains depressed, the hammer is held above its initial resting position by the back check (2); this facilitates rapid repetition of notes.

These appurtenances include a see-saw like leverage-system, the escapement, a supplementary device for repetition, and a check for hammer rebound.

c, found in multiple places, represents a cushion of felt or soft leather upon which the different parts of the action rest or come in contact with each other.

Bnc R, shows the end of the balance rail, underneath the keys and extending the entire length of the keyboard.

In some cases the lead is inserted in the extreme back end of the key; in others it is put near the balance rail according to the requirement.

In this action, the extension is made round at the lower end and fits snugly into a hole in the bottom upon a felt disc.

The brackets rest on supports in and at the sides of the keybed, and are secured at the top by large bolts (BB).

At the top of each bracket is an opening to receive this bolt and a thumbscrew (not shown in the cut, being behind the hammer) which fastens the action securely in position.

It is made fast to the main rail by a screw, and upon it the wippen is hinged by means of a "center-pin" at the lower end.

Its purpose is to assist the hammer to return quickly by hanging to it with the weight of the wippen, extension, jack, etc., when the key is released.

The soft pedal communicates with this rail by a rod which moves it forward and thereby shortens the stroke of the hammers and produces a softer tone.

To make the keybed more compact, many digital keyboards use a pivot point in the rear and hammers underneath the keys, as illustrated.