String (music)

In music, strings are long flexible structures on string instruments that produce sound through vibration. Strings are held under tension so that they can vibrate freely. The pitch (frequency) at which a string will vibrate is primarily related to its vibrating length (also called speaking length), its tension, and its mass per unit of length. A vibrating string produces very little sound by itself. Therefore, most string instruments have a soundboard to amplify the sound.

There are two main kinds of strings; plain and wound. "Plain" strings are simply one piece of long cylindrical material, commonly consisted of nylon or gut. "Wound" strings have a central core, with other material being tightly wound around the string .

Prior to World War II, strings of many instruments (including violins, lutes, and guitars) were made of a material known as catgut, a type of cord made from refined natural fibers of animal intestines. During the mid-twentieth century, steel and nylon strings became more favored in string making, although catgut is still prized for its unique sound. The invention of wound strings (particularly steel) was a crucial step in string instrument technology, because a metal-wound string can produce a lower pitch than a plain gut string of similar thickness. This enabled stringed instruments to be made with thinner bass strings.

On string instruments that the player plucks or bows directly (e.g., double bass), this enabled instrument makers to use thinner strings for the lowest-pitched strings, which made the lower-pitch strings easier to play. On stringed instruments in which the player presses a keyboard, causing a mechanism to strike the strings, such as a piano, this enabled piano builders to use shorter, thicker strings to produce the lowest-pitched bass notes, enabling the building of smaller upright pianos designed for small rooms and practice rooms.

The end of the string that mounts to the instrument's tuning mechanism (the part of the instrument that turns to tighten or loosen string tension) is usually plain. Depending on the instrument, the string's other, fixed end may have either a plain, loop, or ball end (a short brass cylinder) that attaches the string at the end opposite the tuning mechanism. When a ball or loop is used with a guitar, this ensures that the string stays fixed in the bridge of the guitar. When a ball or loop is used with a violin-family instrument, this keeps the string end fixed in the tailpiece. Fender Bullet strings have a larger cylinder for more stable tuning on guitars equipped with synchronized tremolo systems. Strings for some instruments may be wrapped with silk at the ends to protect the string. The color and pattern of the silk often identify attributes of the string, such as manufacturer, size, intended pitch, etc.

Roundwound strings are the simplest and most basic wound strings, they have round wire wrapped in a tight spiral around either a round or hexagonal core. Such strings are usually simple to manufacture, are the least expensive, and are convenient. Despite these advantages, they have several drawbacks, however:

Flatwound strings are strings that have either a round or hex core, and have winding wire that has a rounded square cross-section that has a shallower profile (in cross-section) when tightly wound. This makes for more comfortable playing, and decreased wear for frets and fretboards (this makes them a popular choice for fretless instruments). Squeaking sounds due to fingers sliding along the strings are also decreased significantly. Flatwound strings also have a longer playable life because of smaller grooves for dirt and oil to build up in.

On the other hand, flatwound strings sound less bright than roundwounds and tend to be harder to bend, thus produce vibrato. Flatwounds also are more expensive than roundwounds because of less demand, less production, and higher overhead costs. Manufacturing is also more difficult, as precise alignment of the flat sides of the winding must be maintained (some rotation of the winding on roundwound strings is acceptable).