Violin Mechanics

Construction and Mechanics of a Violin

A violin typically consists of a spruce top (the soundboard, also known as the top plate, table, or belly), maple ribs and back, two endblocks, a neck, a bridge, a soundpost, four strings, and various fittings, optionally including a chinrest, which may attach directly over, or to the left of, the tailpiece. A distinctive feature of a violin body is its hourglass-like shape and the arching of its top and back. The hourglass shape comprises two upper bouts, two lower bouts, and two concave C-bouts at the waist, providing clearance for the bow.

The voice of a violin depends on its shape, the wood it is made from, the graduation (the thickness profile) of both the top and back, and the varnish that coats its outside surface. The varnish and especially the wood continue to improve with age, making the fixed supply of old violins much sought-after.

The very great majority of glued joints in the instrument use animal hide glue for a number of reasons: it is capable of making a thinner joint than most other glues, it is reversible (brittle enough to crack with carefully applied force, and removable with warm water) when disassembly is needed, and since fresh hide glue sticks to old hide glue, more original wood can be preserved when repairing a joint. (More modern glues must be cleaned off entirely for the new joint to be sound, which generally involves scraping off some wood along with the old glue.) Weaker, diluted glue is usually used to fasten the top to the ribs, and the nut to the fingerboard, since common repairs involve removing these parts.

The purfling running around the edge of the spruce top provides some protection against cracks originating at the edge. It also allows the top to flex more independently of the rib structure. Painted-on faux purfling on the top is usually a sign of an inferior instrument. The back and ribs are typically made of maple, most often with a matching striped figure, referred to as flame, fiddleback, or tiger stripe.

The neck is usually maple with a flamed figure compatible with that of the ribs and back. It carries the fingerboard, typically made of ebony, but often some other wood stained or painted black. Ebony is the preferred material because of its hardness, beauty, and superior resistance to wear. Fingerboards are dressed to a particular transverse curve, and have a small lengthwise "scoop," or concavity, slightly more pronounced on the lower strings, especially when meant for gut or synthetic strings.

Some old violins (and some made to appear old) have a grafted scroll, evidenced by a glue joint between the pegbox and neck. Many authentic old instruments have had their necks reset to a slightly increased angle, and lengthened by about a centimeter. The neck graft allows the original scroll to be kept with a Baroque violin when bringing its neck into conformance with modern standards.

The bridge is a precisely cut piece of maple that forms the lower anchor point of the vibrating length of the strings and transmits the vibration of the strings to the body of the instrument. Its top curve holds the strings at the proper height from the fingerboard in an arc, allowing each to be sounded separately by the bow. The sound post, or soul post, fits precisely inside the instrument between the back and top, below the treble foot of the bridge, which it helps support. It also transmits vibrations between the top and the back of the instrument.

The tailpiece anchors the strings to the lower bout of the violin by means of the tailgut, which loops around an ebony button called the tailpin (sometimes confusingly called the endpin, like the cello's spike), which fits into a tapered hole in the bottom block. Very often the E string will have a fine tuning lever worked by a small screw turned by the fingers. Fine tuners may also be applied to the other strings, especially on a student instrument, and are sometimes built into the tailpiece.



At the scroll end, the strings wind around the tuning pegs in the pegbox. Strings usually have a colored silk wrapping at both ends, for identification and to provide friction against the pegs. The tapered pegs allow friction to be increased or decreased by the player applying appropriate pressure along the axis of the peg while turning it.

Strings
Strings were first made of sheep gut (commonly known as catgut), or simply gut, which was stretched, dried, and twisted. Modern strings may be gut, solid steel, stranded steel, or various synthetic materials, wound with various metals, and sometimes plated with silver. Most E strings are unwound, either plain or gold-plated steel.
Strings have a limited lifetime. Apart from obvious things, such as the winding of a string coming undone from wear, players generally change a string when it no longer plays true, losing the desired tone. String longevity depends on string quality and playing intensity.
Pitch range
The compass of the violin is from G3 (G below middle C) to C8 (the highest note of the modern piano.) The top notes, however, are often produced by natural or artificial harmonics. Thus the E two octaves above the open E-string may be considered a practical limit for orchestral violin parts.

Tuning
Violins are tuned by turning the pegs in the pegbox under the scroll, or by adjusting the fine tuner screws at the tailpiece. All violins have pegs; fine tuners (also called fine adjusters) are optional. Most fine tuners consist of a metal screw that moves a lever attached to the string end. They permit very small pitch adjustments much more easily than the pegs. By turning one clockwise, the pitch becomes sharper and turning one counterclockwise, the pitch becomes flatter.

Fine tuners on all four of the strings are a practical necessity for playing steel-core strings, and some players use them with synthetic strings as well. Since modern E strings are steel, a fine tuner is typically fitted for that string. Fine tuners are not used with gut strings, which are more elastic than steel or synthetic-core strings and do not respond adequately to the very small movements of fine tuners.

To tune a violin, the A string is first tuned to a standard pitch (usually 440 Hz), using either a tuning device or another instrument. (When accompanying a fixed-pitch instrument such as a piano or accordion, the violin tunes to it.) The other strings are then tuned against each other in intervals of perfect fifths by bowing them in pairs. A minutely higher tuning is sometimes employed for solo playing to give the instrument a brighter sound; conversely, Baroque music is sometimes played using lower tunings to make the violin's sound more gentle. After tuning, the instrument's bridge may be examined to ensure that it is standing straight and centered between the inner nicks of the f-holes; a crooked bridge may significantly affect the sound of an otherwise well-made violin.

The tuning G-D-A-E is used for most violin music. Other tunings are occasionally employed; the G string, for example, can be tuned up to A. The use of nonstandard tunings in classical music is known as scordatura; in some folk styles, it is called cross-tuning. One famous example of scordatura in classical music is Saint-Saëns' Danse Macabre, where the solo violin's E string is tuned down to E flat to impart an eerie dissonance to the composition. Another example is in the third movement of Contrasts, by Béla Bartók, where the E string is tuned down to E flat and the G tuned to a G sharp, or the set of pieces called the Mystery Sonatas by Biber.
In Indian classical music and Indian light music, the violin is likely to be tuned to D♯-A♯-D♯-A♯ in the South Indian style. As there is no concept of absolute pitch in Indian classical music, any convenient tuning maintaining these relative pitch intervals between the strings can be used. Another prevalent tuning with these intervals is F-B♭-F-B♭, which corresponds to Sa-Pa-Sa-Pa in the Indian carnatic classical music style. In the North Indian Hindustani style, the tuning is usually Pa-Sa-Pa-Sa instead of Sa-Pa-Sa-Pa. This could correspond to B♭-F-B♭-F, for instance.

While most violins have four strings, there are violins with as many as seven strings. The extra strings on such violins typically are lower in pitch than the G-string; these strings are usually tuned to C, F, and B flat. If the instrument's playing length, or string length from nut to bridge, is equal to that of an ordinary full-scale violin; i.e., a bit less than 13 inches (330 mm), then it may be properly termed a violin. Some such instruments are somewhat longer and should be regarded as violas. Violins with five strings or more are often used in jazz or folk music.

Bows
A violin is usually played using a bow consisting of a stick with a ribbon of horsehair strung between the tip and frog (or nut, or heel) at opposite ends. A typical violin bow may be 75 cm (29 inches) overall, and weigh about 60 g (2.1 oz). Viola bows may be about 5 mm (0.20 in) shorter and 10 g (0.35 oz) heavier.
At the frog end, a screw adjuster tightens or loosens the hair. Just forward of the frog, a leather thumb cushion and winding protect the stick and provide a strong grip for the player's hand. The winding may be wire (often silver or plated silver), silk, or whalebone (now imitated by alternating strips of tan and black plastic.) Some student bows (particularly the ones made of solid fiberglass) substitute a plastic sleeve for grip and winding.

The hair of the bow traditionally comes from the tail of a grey male horse (which has predominantly white hair), though some cheaper bows use synthetic fiber. Occasional rubbing with rosin makes the hair grip the strings intermittently, causing them to vibrate. The stick is traditionally made of brazilwood, although a stick made from a more select quality (and more expensive) brazilwood is called pernambuco. Both types come from the same tree species. Some student bows are made of fiberglass or various inexpensive woods. Some recent bow design innovations use carbon fiber for the stick, at all levels of craftsmanship.