A bridge is a device for supporting the strings

Strings (music)

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"...

 on a stringed instrument and transmitting the vibration

Vibration

Vibration refers to mechanical oscillations about an equilibrium point. The oscillations may be periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road.Vibration is occasionally "desirable"...

 of those strings to some other structural component of the instrument in order to transfer the sound

Sound

Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...

 to the surrounding air.

Explanation

Most stringed instruments produce their sound through the application of energy

Energy

In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...

 to the strings, which sets them into vibratory motion. The strings alone, however, produce only a faint sound because they displace

Particle displacement

Particle displacement or particle amplitude is a measurement of distance of the movement of a particle from its equilibrium position in a medium as it transmits a wave....

 only a small volume of air as they vibrate. Consequently, the sound of the strings alone requires impedance matching

Impedance matching

In electronics, impedance matching is the practice of designing the input impedance of an electrical load to maximize the power transfer and/or minimize reflections from the load....

 to the surrounding air by transmitting their vibrations to a larger surface area capable of displacing larger volumes of air (and thus producing louder sounds). This calls for an arrangement that allows for the strings to vibrate freely, but also conducts those vibrations efficiently to the larger surface. A bridge is the customary means by which this is accomplished.

Positioning

Typically, the bridge is placed perpendicular to the strings and larger surface (which are roughly parallel to one another) with the tension

Tension (mechanics)

In physics, tension is the magnitude of the pulling force exerted by a string, cable, chain, or similar object on another object. It is the opposite of compression. As tension is the magnitude of a force, it is measured in newtons and is always measured parallel to the string on which it applies...

 of the strings pressing down on the bridge and thus on the larger surface beneath it. That larger, more acoustically responsive surface may be coupled to a sound chamber — an enclosure such as the body of a guitar

Guitar

The guitar is a plucked string instrument, usually played with fingers or a pick. The guitar consists of a body with a rigid neck to which the strings, generally six in number, are attached. Guitars are traditionally constructed of various woods and strung with animal gut or, more recently, with...

 or violin

Violin

The violin is a string instrument, usually with four strings tuned in perfect fifths. It is the smallest, highest-pitched member of the violin family of string instruments, which includes the viola and cello....

 — that assists in sound amplification. Depending on the type of stringed instrument, the resonant

Resonance

In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...

 surface the bridge rests on may be made of wood, as the top plate of a guitar

Guitar

The guitar is a plucked string instrument, usually played with fingers or a pick. The guitar consists of a body with a rigid neck to which the strings, generally six in number, are attached. Guitars are traditionally constructed of various woods and strung with animal gut or, more recently, with...

 or violin

Violin

The violin is a string instrument, usually with four strings tuned in perfect fifths. It is the smallest, highest-pitched member of the violin family of string instruments, which includes the viola and cello....

; of calfskin or plastic, as the head of a banjo

Banjo

In the 1830s Sweeney became the first white man to play the banjo on stage. His version of the instrument replaced the gourd with a drum-like sound box and included four full-length strings alongside a short fifth-string. There is no proof, however, that Sweeney invented either innovation. This new...

; of metal, as on certain types of resophonic fretted instruments; or of virtually any material that vibrates sympathetically with the strings.

Construction

Bridges may consist of a single piece of material, most commonly wood, that fits between the strings and the resonant surface. Alternatively, a bridge may consist of multiple parts. One common form is a bridge that incorporates a separate bearing surface on which the strings rest, termed a saddle. This is often of a material harder than the bridge itself, such as bone, ivory, high-density plastic, or metal. A classical guitar uses a saddle which sits loosely in the hardwood bridge and is kept there by string tension. The saddle has shallow grooves in it, at least for the treble strings, to prevent them moving around during hard playing.

Yet another type of multipart bridge is common on instruments whose sound plate is curved rather than flat. Instruments of this type, such as arch-top guitar

Guitar

The guitar is a plucked string instrument, usually played with fingers or a pick. The guitar consists of a body with a rigid neck to which the strings, generally six in number, are attached. Guitars are traditionally constructed of various woods and strung with animal gut or, more recently, with...

s and mandolin

Mandolin

A mandolin is a musical instrument in the lute family . It descends from the mandore, a soprano member of the lute family. The mandolin soundboard comes in many shapes—but generally round or teardrop-shaped, sometimes with scrolls or other projections. A mandolin may have f-holes, or a single...

s, often have a bridge comprising a base and a separate saddle that can be adjusted for height. On classical and flat-top guitars the bridge is glued
to the top. Where it held on to the top by string tension, as in archtop guitars, it is known as a floating bridge, and requires a separate tailpiece.

Operation

The bridge must transfer vibration to the sound board

Sounding board

A sound board, or soundboard, is the surface of a string instrument that the strings vibrate against, usually via some sort of bridge. The resonant properties of the sound board and the interior of the instrument greatly increase loudness over the string alone.The sound board operates by the...

 or other amplifying surface. As the strings are set in motion, it does this by bending to and fro along the string direction at twice the rate of the string vibration. This causes the sounding board to vibrate at the same frequency as the string producing a wave-like motion and an audible sound.

Bridges are designed to hold the strings at a suitable height above the fingerboard

Fingerboard

The fingerboard is a part of most stringed instruments. It is a thin, long strip of material, usually wood, that is laminated to the front of the neck of an instrument and above which the strings run...

 of the instrument. The ideal bridge height is one that creates sufficient angularity in the string to create enough down force to drive the top but places the strings sufficiently close to the fingerboard to make noting the strings easy. Bridge height may be fixed or alterable.

In addition to supporting the strings and transmitting their vibrations, the bridge also controls the spacing of the strings from one another. This is accomplished by shallow grooves cut in the bridge or its saddle. The strings sit in those grooves and thus are held in their proper lateral position. The nut, situated at the opposite end of the instrument from the bridge or tailpiece (typically where the head holding the tuning pegs joins the fingerboard), serves a similar string-spacing function at the strings' other end.

Electric guitar bridges

Bridges for electric guitars can be divided into two main groups, "tremolo

Tremolo arm

A whammy bar, tremolo arm/bar, or vibrato arm/bar is a component of a guitar, used to add vibrato to the sound by changing the tension of the strings, typically at the bridge or tailpiece...

" and "non-tremolo" (also called hard-tail). Tremolo bridges have an arm (called the tremolo or whammy bar) that extends from below the string anchoring point. It acts as a lever

Lever

In physics, a lever is a rigid object that is used with an appropriate fulcrum or pivot point to either multiply the mechanical force that can be applied to another object or resistance force , or multiply the distance and speed at which the opposite end of the rigid object travels.This leverage...

 that the player can push or pull to change the strings tension

Tension (mechanics)

In physics, tension is the magnitude of the pulling force exerted by a string, cable, chain, or similar object on another object. It is the opposite of compression. As tension is the magnitude of a force, it is measured in newtons and is always measured parallel to the string on which it applies...

 and, as a result, the pitch

Pitch (music)

Pitch is an auditory perceptual property that allows the ordering of sounds on a frequency-related scale.Pitches are compared as "higher" and "lower" in the sense associated with musical melodies,...

. This means that this type of bridge produces a vibrato

Vibrato

Vibrato is a musical effect consisting of a regular, pulsating change of pitch. It is used to add expression to vocal and instrumental music. Vibrato is typically characterised in terms of two factors: the amount of pitch variation and the speed with which the pitch is varied .-Vibrato and...

 rather than tremolo, but the term is deeply entrenched in popular usage. Non-tremolo bridges supply an anchoring point for the strings but provide no active control over string tension or pitch. A small group of tremolo bridges has an extended tail (also called longtail). These guitars have more reverb in their sound, because of the string resonance behind the bridge. The Fender Jaguar

Fender Jaguar

The Fender Jaguar is an electric guitar introduced in 1962. A descendant of the Jazzmaster, the Jaguar quickly caught on in the emerging Surf music scene...

 is a famous example of such a guitar.

All bridges have advantages, depending on the playing style, but, in general, a non-tremolo bridge is thought to provide better tuning stability and a solid contact between the guitar body and the strings.

Tremolo bridges

Generally, the more contact the bridge has with the body (i.e. the lower the position), the better the sound transfer will be into the body. A warmer sound with increased sustain is the result.

Tremolo bridges usually need to be suspended in some way, which reduces contact. Most tremolo designs today use a group of springs

Spring (device)

A spring is an elastic object used to store mechanical energy. Springs are usually made out of spring steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel and hardened after fabrication...

 in the guitar body, which oppose the tension of the strings. Some players feel that the vibration of the springs affects resonance

Resonance

In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...

 in a way that makes the guitar sound better; others disagree. Naturally, it all depends on personal preference and the musical style of the individual player.

Since many playing styles make use of a tremolo obligatory, most solid-body guitars today are manufactured with one of two kinds of tremolos:

Non-Locking Tremolo

Non-locking (or vintage) tremolos are the bridges found on all guitars manufactured prior to the advent of the Floyd Rose

Floyd Rose

The Floyd Rose Locking Tremolo, or simply Floyd Rose, is a type of locking vibrato arm for a guitar. The first of its kind, Floyd D. Rose invented the locking vibrato in 1977, and it is now manufactured by a company of the same name...

 locking tremolo in the late 1970s and many (typically cheaper) guitars manufactured thereafter. For many playing styles, vintage tremolos are a good choice because they are easy to use and maintain and have very few parts. Some people feel that they can also provide a better degree of sound transfer, especially with tailpiece type tremolos such as the Bigsby. However, "Synchronized Tremolo" type found on the Fender Stratocaster is balanced against a set of screws in much the same manner as a locking tremolo and offers little improvement in the way of sounds transfer. Given that this type of tremolo is installed on solid body guitars the degree to which sound transfer affects the sound that the instrument produces is minimal. Also, keeping a guitar with a non-locking tremolo in tune can be difficult. The most common types of non-locking tremolos are the "Synchronized Tremolo" type and an almost endless stream of copies. The Bigsby vibrato tailpiece is another option, although that type has largely fallen out of favour.

Locking Tremolo

Another type of tremolo is the locking tremolo. These bridges have a sort of vise in each saddle which clamps the string into place (usually with an Allen key). The end of the string has a clamp, which holds the string in place, stopping it from slipping. This is especially useful for songs that require tapping or heavy/hard playing styles. Once set up for tuning stability, locking tremolos are very good. However, their fulcrum points offer extremely minute contact with the body, which may disturb sound transfer.

Non-Tremolo bridges

]
It is generally thought that non-tremolo bridges offer better transfer of string vibration into the body. This is due to direct contact of the bridge to the guitar's body.

These bridges are bolted directly to the guitar body and, assuming good quality, limit longitudinal string movement completely. Therefore tuning stability is assured.

The improved transfer of string vibration into the body has an effect on the sound, so guitars with this type of bridge have different characteristics than those with tremolos even when it is removed. There are no springs in the body or a cavity to accommodate them, which also affects resonance.

See also

• Fingerboard
  Fingerboard
  The fingerboard is a part of most stringed instruments. It is a thin, long strip of material, usually wood, that is laminated to the front of the neck of an instrument and above which the strings run...
  
  
• Electronic tuner
  Electronic tuner
  The term electronic tuner can refer to a number of different things, depending which discipline you wish to study.In the Discipline of radio frequency electronics an electronic tuner is a device which tunes across a part of the radio frequency spectrum by the application of a voltage or appropriate...
  
  Some tuners attach to the bridge of an instrument.

External links

• violinbridges.co.uk -- Online bridge archive