String (music)

Flatwound strings on fretless bass guitar

A string is the vibrating element that produces sound in string instruments, such as the guitar, harp, piano, and members of the violin family. Strings are lengths of a flexible material kept under tension so that they may vibrate freely, but controllably. Strings may be "plain" (consisting only of a single material, like steel, nylon, or gut). "Wound" strings, on the other hand, have a "core" of one material, with an overwinding of other materials. This is to make the string vibrate at the desired pitch, while maintaining a low profile and sufficient flexibility for purposes of playability.

String construction

Depending on the instrument they are designed for, strings have either a loop end or ball end (actually a short brass cylinder) that attaches the string at the end opposite the tuning mechanism. Strings for some instruments may be wrapped with silk at their ends to protect the string. The color and pattern of the silk can be used to identify the size and denomination of the string.

Winding

There are several varieties of wound strings.

Roundwound

The simplest strings are roundwound. They have either a round core or a hex core inside and round winding wire, wound in a tight spiral around it. Such strings are usually simple to manufacture and, thus, are usually the least expensive. There are several drawbacks, however:

• Roundwound strings have a "bumpy" surface profile (the "bumps" of the winding) that can produce friction when in contact with the player's fingertips. This causes "squeaking" sounds when the player's fingers slide over the strings. Some artists use this sound creatively on purpose.
• Non-flat, high-friction surface profile may hasten fingerboard and fret wear.
• When the core is round, the winding is not secured to the core and can rotate freely around it, especially if the winding is damaged after use.
  

  

Flatwound

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

On the other hand, players frequently cite that flatwound strings produce a less bright sound when compared to roundwounds. Flatwounds also usually cost slightly more than roundwounds.

Halfwound, ground wound, pressure wound

Halfwound strings, ground wound strings or pressure wound strings are a cross between roundwound and flatwound. Such strings are usually made by winding round wire around a round or hex core first, then polishing, grinding (thus the name, ground wound) or pressing the exterior part of the winding until it is practically flat. This results in the flat, comfortable playing feel of flatwounds, along with less squeaking, without sacrificing the tonal characteristics that come with roundwounds. The polishing process removes almost half of the winding wire's mass, thus, to compensate for it, manufacturers use winding wire of a heavier gauge.

Hexcore

Hexcore strings are composed of regular hexagonal core and a tight (usually round) winding. It prevents the winding from slipping around the core - a problem usually associated with round core strings. The hexagonal cross-section of the core provide pressure points that help secure the winding around the core better, to prevent unwanted slipping and subsequent rotation.

Gauge

A wound acoustic guitar string (phosphor bronze wound around steel) with a ball end, 0.044" gauge

Bowed instrument strings such as those for the violin or cello are usually not described by their gauge. These strings are usually described by their tension. The discussion here primarily concerns fretted instruments.

The tone of a string depends partly on its weight, and, therefore, on its diameter or so-called gauge. Traditionally, a string's diameter is measured in thousandths of an inch (0.001 in = 0.0254 mm). The larger the diameter, the heavier the string is. Heavier strings require more tension for the same pitch and are, as a consequence, harder to press down to the fingerboard. If a fretted instrument is restrung with different string gauges, it may be necessary to adjust string height above the frets, (the "action") to make the instrument easier to play or keep the strings from buzzing against the frets. The action height of fretless instruments is also adjusted to suit the string gauge or material, as well as the intended playing style.

Steel strings for 6-string guitar usually come in sets of matched strings. Sets are usually referenced either by the gauge of the first string (e.g., 9), or by pair of first and last (e.g., 9-42). Some manufacturers may have slightly different gauge sequences; the sample data below comes from D'Addario string charts for regular, round-wound, nickel-plated strings.

Electric Guitar

(Note: strings in dark gray boxes are wound. All others are plain.)

Name	1 (E)	2 (B)	3 (G)	4 (D)	5 (A)	6 (E)
Extra super light (8-38)	.008	.010	.015	.021	.030	.038
Extra super light plus (8.5-39)	.0085	.0105	.015	.022	.032	.039
Super light (9-42)	.009	.011	.016	.024	.032	.042
Super light plus (9.5-44)	.0095	.0115	.016	.024	.034	.044
Regular light (10-46)	.010	.013	.017	.026	.036	.046
Extra light w/heavy bass (9-46)	.009	.013	.021	.029	.036	.046
Medium (11-48)	.011	.014	.018	.028	.038	.048
Light Top / Heavy Bottom (10-52)	.010	.013	.017	.032	.042	.052
Medium w/wound G string (11-52)	.011	.013	.020	.030	.042	.052
Heavy (12-54)	.012	.016	.020	.032	.042	.054
Extra heavy (13-56)	.013	.017	.026	.036	.046	.056

Acoustic Guitar

(Note: strings in dark gray boxes are bronze wound. All others are plain.)

Name	1 (E)	2 (B)	3 (G)	4 (D)	5 (A)	6 (E)
Super light (10-46)	.010	.013	.020	.026	.036	.046
Extra light (11-50)	.011	.014	.022	.030	.038	.050
Light (12-54)	.012	.016	.024	.032	.042	.054
Medium (13-56)	.013	.017	.026	.036	.046	.056
Heavy(14-58)	.014	.018	.028	.038	.048	.058

Bass Guitar

Typical bass guitar strings come in the following gauges. Bass guitar strings are sometimes made for a particular scale length and come in short, medium, long and extra long (sometimes called super long) scale.

Name	1 (G)	2 (D)	3 (A)	4 (E)	5 (B)
Light or "soft" (40-100)	.040	.060	.080	.100	.125
Medium (45-105)	.045	.065	.085	.105	.130
Heavy (50-110)	.050	.075	.095	.110	.135

Note that some manufacturers of strings produce other sets of strings, too; the figure above merely lists the most commonly used combinations.

Strings for violin family instruments are often sold in 3 gauges simply labeled heavy, medium, and light, which do not have a standard size associated with them. (These gauges are sometimes called by their German names, stark, mittel, and weich.)

Tension

Bowed instrument (violin, viola, etc.) strings are differentiated by their tension rather than their gauge. The available tensions for orchestral strings are typically light, medium and heavy, with medium being the standard.

Materials

Core

Steel forms the core for almost all metal strings. Certain keyboard instruments (eg harpsichord) and the Gaelic harp use brass. Other natural materials such as silk or gut, or synthetics such as nylon and kevlar are also used for string cores. (Steel used for strings, called music wire, is hardened and tempered.) Some violin E strings are gold-plated to improve tone quality.

Sheep and bull gut (called catgut, even though cats were never used for this purpose) were the original materials used as cores for strings for violin family instruments. Gut strings are subject to changes in humidity, which cause them go out of tune, and they also break more easily than other core materials. However, even after the introduction of metal and synthetic core materials, gut strings remain in widespread use because their warmer tone is preferable to some players. Modern gut strings are usually wrapped in metal. Nylgut strings are a recently developed alternative to gut strings - made from a plastic material, they offer almost exactly the same acoustic properties as gut strings, but with none of the problems of tuning caused by climatic variations. Many players of early music now use them in preference to genuine gut.

Silk was extensively used in China for traditional Chinese musical instruments until they were replaced by metal-nylon strings in the 1950s. Only the silk strings used for the guqin are still produced; the quality in ancient times was very high to the extent that there was a brand praised as 'ice strings' because of their smoothness and translucent appearance.

At the present time, one of the most popular materials for the cores of violin, viola, cello, and double bass strings is stranded nylon, often sold under the trade name of Perlon.

Nylon guitar strings were first developed by Albert Augustine Strings in 1947.

Today, most jazz and folk string players prefer steel-core strings for their faster response, low cost, and tuning stability, whereas most classical string players prefer synthetic-core strings (Perlon etc.) for their richer overtones and "warmer" tone. Most baroque string players still prefer gut-core strings.

By far the most popular string combination for a modern concert violinist is synthetic-core G, D, and A strings, with a steel E string.

Winding

Aluminum, silver, and chrome steel are common windings for bowed instruments like violin and viola, whereas acoustic guitar and piano strings are usually wound with bronze. Classical guitar strings are typically nylon, with the basses being wound with either silver or bronze. Electric guitar strings are usually wound with nickel plated steel; pure nickel and stainless steel are also used. Bass guitar strings are most commonly wound with stainless steel or nickel. Copper, gold, silver, and tungsten are used for some instruments. Silver and gold are more expensive, and are used for their resistance to corrosion and hypoallergenicity.

Some "historically-informed" strings use an open metal winding with a "barber pole" appearance.

"Silk and steel" guitar strings are overwound steel strings with silk filaments running under the winding.

String vibration

Main article: Vibrating string

A string vibrates in a complex harmonic pattern. Every time a string is set into motion, a specific set of frequencies resonate based on the harmonic series. The fundamental frequency is the lowest (and loudest), and it is determined by the density, length and tension of the string. This is the frequency that we identify as the pitch of the string. Above that frequency, overtones (or harmonics) are heard, each one getting quieter the higher it is. For example, if the fundamental pitch is 440 Hz (A above middle C), the overtones for an ideal string tuned to that pitch are 880 Hz, 1320 Hz, 1760 Hz, 2200 Hz, etc. The note names for those pitches would be A, A, E, A, C#, etc. Due to the physical nature of the strings, however, the higher up the overtones go, the more out of tune (or "false") they are to the fundamental. This is an important consideration for piano tuners, who try to stretch the tuning across the piano to keep overtones more in tune as they go up the keyboard.

String corrosion

Metal strings offer a unique problem, as they are susceptible to oxidation and corrosion. Wound strings that use metals such as brass or bronze in their winding eventually corrode as moisture and salts from the player's fingers build up oxides on the string. As a result, the string loses its brilliance over time. To help solve this problem, some string manufacturers apply a metal plating or polymer coating to protect the string from corrosion, and some companies sell special lubricating oils which may slow down oxidation.

See also

• Violin construction and mechanics
• Electronic tuner
• Harmonic oscillator

External links

• Identify strings by their silk patterns
• The vibrations of strings with both ends fixed
• Guitar Strings From The Nineteenth Century To The Advent Of Nylon
• Historical types of string
• String Calculation; String Measurement; Mass Per Unit Length
• Custom String Gauge Design Terry Downs
• String Tension - technical information on string tension, with tension calculator