GUITAR STRINGS

A string is the vibrating element which is the source of vibration in string instruments, such as the guitar, harp, piano, and members of the violin family. They are lengths of a flexible material kept under tension so that they may freely vibrate. Strings may be "plain" (consisting only of a single material, like steel, nylon, or gut) or they may have a core of one material with an overwinding of other materials to add mass so the string sounds the desired pitch, while keeping the string thin and flexible enough to play. Such strings are called "wound strings."

String construction

Depending on the construction of the instrument they are used on, strings will usually have either a ball or loop at one end to attach the string to the instrument. 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 string.

Winding

There are several varieties of wound strings.

Roundwound

The simplest ones are the roundwound strings. They have a round 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, though:

• Roundwound strings have a surface profile (the "bumps" of the winding) that causes "squeaking" sounds when the player's fingers slide over the strings. While some artists use this sound creatively on purpose, this sound is generally unwanted.
• Non-flat surface profile also hastens fingerboard and fret wire wear.
• The winding is not secured to the core and can rotate freely around it, especially if the winding is damaged after use. It makes it harder to push down and hold the strings with the fingers, and thus impairs the general playing experience.
  
  

Flatwound

Flatwound strings also have a round core, but the winding wire has a rounded square cross-section. When tightly wound, such strings have a much shallow profile (in cross-section), thus making them more comfortable to play, less damaging for frets / fretboard and producing quieter squeak sounds from fingers sliding along the string. However, players frequently cite that the sound of flatwound strings differs considerably from the sound of roundwound, with less brightness.

Halfwound, ground wound, pressure wound

Halfwound strings, ground wound strings or pressure wound strings are a cross between roundwound and flatwound, providing both the tonal characteristics of roundwound and the lack of squeaking and the playing feel of flatwound. Such strings are usually made by winding round wire around a round core first, then polishing, grinding (thus the name, ground wound) or pressing the exterior part of the winding until it is practically flat.

Note that polishing process removes almost half of winding wire mass, thus, to compensate for it, manufacturers have to use heavier gauge winding wire. In its turn, thicker winding wire lowers frequency of slide squeaking. Depending on sound processing, it can be a good thing (as squeaking becomes less accented and it will be masked out by performed music) or a bad thing (high-pitched squeaks are much easier to detect and filter out when recording).

Hexwound

Hexwound strings are composed of regular hexagonal core and a tight (usually round) winding that closely fits a hexagonal shape. It solves the second problem: it secures the winding around the core, so it can't rotate and slip under the fingers. Sometimes it's cited that hexagonal core improves tones due to closer bond between the core and the winding The drawback is that relatively sharp hexagonal corners are less comfortable for fingers and wear down the fingerboard and fret wire even faster than roundwound strings. Hexwound strings are more commonly used on bass instruments (such as bass guitars).

Gauge

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

Steel strings for 6-string guitar usually come in the 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.

(Note: strings in 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
Super light (9-42)	.009	.011	.016	.024	.032	.042
Regular light (10-46)	.010	.013	.017	.026	.036	.046
Extra light w/heavy bass (9-46)	.009	.013	.021	.029	.036	.046
Medium (11-49)	.011	.014	.018	.028	.038	.049
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

Typical bass guitar strings come in the following gauges. Note that additional strings (5th and 6th) are usually sold separately. Bass guitar strings are sometimes made for a particular scale length and come in short, medium and long scale.

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

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".)

info : Wikipedia