Piano - Keyboard strings

Single escapement action

Allows jack to disengage before the hammer head reaches the string. The hammer falls back almost to its original position and is held by the back check until the key is released.

Double escapement action

Contains an extra repetition lever which holds the rebounding hammer close to the string. This allows quick repetition of a note, without completely releasing the key.

Overstrung piano

The bass strings run above the shorter treble strings, and are attached to the bass bridge. The treble strings are attached to the treble bridge.

Amount of strings struck

Most of the keys on a piano strike three strings simultaneously. These strings are tuned to slightly different frequencies. Initially they vibrate in phase but due to the slight mistuning they get out of phase overtime (slower transfer of energy to the soundboard and longer sound).

Stiffness of strings

Due to the stiffness of strings (thicker ones) it introduces a restoring force. This means mode frequencies of the strings are no longer exactly harmonic.

Pedals

Una corda - Shifting of the action and only two strings are struck

Sustain - Lifts the dampers of the pedals

Sostenuto pedal - Only keeps up the dampers of strings where the key was pressed.

Soundboard

Vibrations of the strings are transmitted to the soundboard via the bridge. The soundboard is the main resonator in a piano.

Resonance modes

The soundbaord has many resonant modes, which overlap to give an approximately uniform frequency response over the playing range of the instrument.

Timbre of the piano

Spectrum depends on range

• Higher notes have less harmonics

• Softer notes have less harmonics

• Attack transient (the way the sound starts)