Bridge (instrument)
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A bridge is a device that supports the strings on a
stringed musical instrument In musical instrument classification, string instruments, or chordophones, are musical instruments that produce sound from vibrating strings when a performer strums, plucks, strikes or sounds the strings in varying manners. Musicians play so ...
and transmits the
vibration Vibration () is a mechanical phenomenon whereby oscillations occur about an equilibrium point. Vibration may be deterministic if the oscillations can be characterised precisely (e.g. the periodic motion of a pendulum), or random if the os ...
of those strings to another structural component of the instrument—typically a soundboard, such as the top of a guitar or violin—which transfers the
sound In physics, sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the br ...
to the surrounding air. Depending on the instrument, the bridge may be made of carved wood ( violin family instruments,
acoustic guitar An acoustic guitar is a musical instrument in the string family. When a string is plucked, its vibration is transmitted from the bridge, resonating throughout the top of the guitar. It is also transmitted to the side and back of the instrument, ...
s and some
jazz guitar Jazz guitar may refer to either a type of electric guitar or a guitar playing style in jazz, using Guitar amplifier, electric amplification to increase the volume of acoustic guitars. In the early 1930s, jazz musicians sought to amplify their ...
s), metal (
electric guitar An electric guitar is a guitar that requires external electric Guitar amplifier, sound amplification in order to be heard at typical performance volumes, unlike a standard acoustic guitar. It uses one or more pickup (music technology), pickups ...
s such as the
Fender Telecaster The Fender Telecaster, colloquially known as the Tele (), is an electric guitar produced by Fender (company), Fender. Together with its sister model the Fender Esquire, Esquire, it was the world's first mass-produced, commercially successfulLes ...
) or other materials. The bridge supports the strings and holds them over the body of the instrument under tension.


Explanation

Most stringed instruments produce sound through the application of
energy Energy () is the physical quantity, quantitative physical property, property that is transferred to a physical body, body or to a physical system, recognizable in the performance of Work (thermodynamics), work and in the form of heat and l ...
to the strings, which sets them into vibratory motion, creating musical sounds. The strings alone, however, produce only a faint sound because they displace only a small volume of air as they vibrate. Consequently, the sound of the strings alone requires
impedance matching In electrical engineering, impedance matching is the practice of designing or adjusting the input impedance or output impedance of an electrical device for a desired value. Often, the desired value is selected to maximize power transfer or ...
to the surrounding air by transmitting their vibrations to a larger surface area that displaces a larger volume of air (and thus produces louder sounds). This calls for an arrangement that lets the strings vibrate freely, but also conducts those vibrations efficiently to the larger surface. A bridge is the customary means for accomplishing this. The bridge conducts the vibrations of the strings to a hollowed out chamber in a number of instruments (e.g., violin family,
acoustic guitar An acoustic guitar is a musical instrument in the string family. When a string is plucked, its vibration is transmitted from the bridge, resonating throughout the top of the guitar. It is also transmitted to the side and back of the instrument, ...
,
balalaika The balalaika (, ) is a Russian string instrument, stringed musical instrument with a characteristic triangular wooden, hollow body, fretted neck, and three strings. Two strings are usually tuned to the same note and the third string is a perf ...
). On
electric guitar An electric guitar is a guitar that requires external electric Guitar amplifier, sound amplification in order to be heard at typical performance volumes, unlike a standard acoustic guitar. It uses one or more pickup (music technology), pickups ...
s and electric basses, the bridge conducts the vibrations to the body, but the vibrations of the strings are typically sensed by a
magnetic pickup A pickup is an electronic device that converts energy from one form to another that captures or senses mechanical vibrations produced by musical instruments, particularly stringed instruments such as the electric guitar, and converts these t ...
, so that an electric signal is created, which is then connected to a
guitar amplifier A guitar amplifier (or amp) is an electronic amplifier, electronic device or system that strengthens the electrical signal from a Pickup (music technology), pickup on an electric guitar, bass guitar, or acoustic guitar so that it can produce so ...
and a
speaker enclosure A loudspeaker enclosure or loudspeaker cabinet is an enclosure (often rectangular box-shaped) in which speaker drivers (e.g., woofers and tweeters) and associated electronic hardware, such as Audio crossover, crossover circuits and, in some ca ...
to produce the sound the performer and audience hears. On
electric piano An electric piano is a musical instrument that has a piano-style musical keyboard, where sound is produced by means of mechanical hammers striking metal strings or reeds or wire tines, which leads to vibrations which are then converted into ele ...
s, the player presses or strikes keys, which cause hammers to strike metal tines. A magnetic pickup senses these vibrations, using the same approach as with an electric guitar (amplifier and speaker).


Positioning

Typically, the bridge is perpendicular to the strings and larger surface (which are roughly parallel to one another) with the tension 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 The guitar is a stringed musical instrument that is usually fretted (with Fretless guitar, some exceptions) and typically has six or Twelve-string guitar, twelve strings. It is usually held flat against the player's body and played by strumming ...
or
violin The violin, sometimes referred to as a fiddle, is a wooden chordophone, and is the smallest, and thus highest-pitched instrument (soprano) in regular use in the violin family. Smaller violin-type instruments exist, including the violino picc ...
—that provides resonance that helps amplify the sound. Depending on the type of stringed instrument, the resonant surface the bridge rests on may be made of: * Wood, as the top "plate" piece of wood of a
guitar The guitar is a stringed musical instrument that is usually fretted (with Fretless guitar, some exceptions) and typically has six or Twelve-string guitar, twelve strings. It is usually held flat against the player's body and played by strumming ...
or
violin The violin, sometimes referred to as a fiddle, is a wooden chordophone, and is the smallest, and thus highest-pitched instrument (soprano) in regular use in the violin family. Smaller violin-type instruments exist, including the violino picc ...
* Calfskin or plastic under tension, as with a
drum The drum is a member of the percussion group of musical instruments. In the Hornbostel–Sachs classification system, it is a membranophone. Drums consist of at least one membrane, called a drumhead or drum skin, that is stretched over a ...
, as on the head of a
banjo The banjo is a stringed instrument with a thin membrane stretched over a frame or cavity to form a resonator. The membrane is typically circular, and in modern forms is usually made of plastic, where early membranes were made of animal skin. ...
* Metal, as on certain types of resophonic fretted instruments * Virtually any material that can vibrate sympathetically with the strings. Some
upright bass The double bass (), also known as the upright bass, the acoustic bass, the bull fiddle, or simply the bass, is the largest and lowest-pitched string instrument, chordophone in the modern orchestra, symphony orchestra (excluding rare additions ...
es are made of aluminium. Some violin family instruments are made of carbon fibre.


Construction

Bridges may consist of a single piece of material, most commonly wood for violins and acoustic guitars, that fits between the strings and the resonant surface. Alternatively, a bridge may consist of multiple parts. One common form is a bridge with a separate bearing surface, called a ''saddle'', that supports the strings. This is often of a material harder than the bridge itself, such as bone, ivory, high-density plastic, or metal. Some acoustic guitar bridges have multiple materials, such as a bridge support and "feet" made of wood and a plastic or bone "ridge" where the strings are positioned against. A classical guitar saddle sits loosely in the hardwood bridge, held in place by string tension. Strings pass through shallow grooves in the saddle, at least for the treble strings, which prevents them moving around during hard playing. Yet another type of multi-part bridge is common on instruments with a curved sound plate, such as an arch-top
guitar The guitar is a stringed musical instrument that is usually fretted (with Fretless guitar, some exceptions) and typically has six or Twelve-string guitar, twelve strings. It is usually held flat against the player's body and played by strumming ...
or
mandolin A mandolin (, ; literally "small mandola") is a Chordophone, stringed musical instrument in the lute family and is generally Plucked string instrument, plucked with a plectrum, pick. It most commonly has four Course (music), courses of doubled St ...
. Such instruments often have a bridge with a base and separate saddle that can be adjusted for height. On classical and flat-top guitars the bridge is glued to the top. A bridge held on to the top by string tension, as in banjos and archtop
jazz guitar Jazz guitar may refer to either a type of electric guitar or a guitar playing style in jazz, using Guitar amplifier, electric amplification to increase the volume of acoustic guitars. In the early 1930s, jazz musicians sought to amplify their ...
s, is called a ''floating bridge'', and requires a separate tailpiece to anchor the strings.
Electric guitar An electric guitar is a guitar that requires external electric Guitar amplifier, sound amplification in order to be heard at typical performance volumes, unlike a standard acoustic guitar. It uses one or more pickup (music technology), pickups ...
s typically have a metal bridge, often with adjustable intonation screws.


Bridge pin

Bridge pins or string pegs are used on some musical instruments to locate the
string String or strings may refer to: *String (structure), a long flexible structure made from threads twisted together, which is used to tie, bind, or hang other objects Arts, entertainment, and media Films * ''Strings'' (1991 film), a Canadian anim ...
precisely in the horizontal plane, and in the case of harpsichords to affect the sustain of the strings. They are usually made of steel in modern
piano A piano is a keyboard instrument that produces sound when its keys are depressed, activating an Action (music), action mechanism where hammers strike String (music), strings. Modern pianos have a row of 88 black and white keys, tuned to a c ...
s, of brass in
harpsichord A harpsichord is a musical instrument played by means of a musical keyboard, keyboard. Depressing a key raises its back end within the instrument, which in turn raises a mechanism with a small plectrum made from quill or plastic that plucks one ...
s, and bone or synthetics on acoustic
guitars The guitar is a stringed musical instrument that is usually fretted (with Fretless guitar, some exceptions) and typically has six or Twelve-string guitar, twelve strings. It is usually held flat against the player's body and played by strumming ...
. Electric guitars do not usually have bridge pins as with acoustic guitars; they are used to transfer the sound from the strings into the hollow body of the instrument as well as holding the strings in place. In pianos the pins are set precisely in line with the edges of the notches of the bridge. The precise and firm setting of the pins is a critical element of the piano's quality. Loose or inaccurate pinning commonly produces false beats and tonal irregularities. In harpsichords there tends to be a significant distance instead. This enables control of sustain and tone in harpsichord design (as per external link).


Tie block

The bridge of the classical guitar does not use bridge pins. In this instrument the strings are tied to the part of the bridge called the tie block. Strings run over the bridge saddle, through drilled holes in the base of the tie block, loop over the top of the tie block, loop under the strings and are tied on. A variation called the 18 hole bridge uses three holes per string and eliminates the need to tie the string down.


Operation

The bridge must transfer vibration of the strings to the sound board or other amplifying surface. As the strings are set in motion (whether by picking or strumming, as with guitars, by bowing, with violin family instruments, or by striking them, as with pianos), the bridge bends 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. Instruments typically use a hollow, resonant chamber (violin bodies, guitar bodies) or a pickup and an amplifier/speaker to make this sound loud enough for the performers and audience to hear. Bridges are designed to hold the strings at a suitable height above the
fingerboard The fingerboard (also known as a fretboard on fretted instruments) is an important component 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. The stri ...
of the instrument. The ideal bridge height 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. Most violin-family bridges are carved by a
luthier A luthier ( ; ) is a craftsperson who builds or repairs string instruments. Etymology The word ' is originally French and comes from ''luth'', the French word for "lute". The term was originally used for makers of lutes, but it came to be ...
; as such, the height can be changed, but only by taking the violin into the repair shop. Many acoustic guitars have fixed bridges that a regular player cannot adjust. Some archtop
jazz guitar Jazz guitar may refer to either a type of electric guitar or a guitar playing style in jazz, using Guitar amplifier, electric amplification to increase the volume of acoustic guitars. In the early 1930s, jazz musicians sought to amplify their ...
s have a "floating bridge" similar to violin family instruments. In addition to supporting the strings and transmitting their vibrations, the bridge also controls the spacing between strings with shallow grooves cut in the bridge or its saddle. The strings sit in those grooves, thus are held in their proper lateral position. The ''nut'', 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. As well, like the bridge, the nut's height determines how high the strings are from the fingerboard.


Electric guitar bridges

Bridges for electric guitars can be divided into two main groups, "
vibrato Vibrato (Italian language, Italian, from past participle of "wikt:vibrare, vibrare", to vibrate) is a musical effect consisting of a regular, pulsating change of pitch (music), pitch. It is used to add expression to vocal and instrumental music. ...
" and "non-vibrato" (also called "hard-tail"). Vibrato bridges have an arm or lever (called the vibrato arm, tremolo arm, or "whammy bar") that extends from below the string anchoring point. It acts as a
lever A lever is a simple machine consisting of a beam (structure), beam or rigid rod pivoted at a fixed hinge, or '':wikt:fulcrum, fulcrum''. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, l ...
that the player can push or pull to change the strings' tension and, as a result, "bend" the pitch down or up. This means that this type of bridge produces
vibrato Vibrato (Italian language, Italian, from past participle of "wikt:vibrare, vibrare", to vibrate) is a musical effect consisting of a regular, pulsating change of pitch (music), pitch. It is used to add expression to vocal and instrumental music. ...
(a pitch change) rather than actual
tremolo In music, ''tremolo'' (), or ''tremolando'' (), is a trembling effect. There are multiple types of tremolo: a rapid repetition of a note, an alternation between two different notes, or a variation in volume. Tremolos may be either ''measured'' ...
, but the term "tremolo" is deeply entrenched in popular usage via some manufacturers (starting with
Fender Stratocaster The Fender Stratocaster, colloquially known as the Strat, is a model of double- cutaway electric guitar designed between 1952 and 1954 by Leo Fender, Bill Carson, George Fullerton, and Freddie Tavares. The Fender Musical Instruments Corpora ...
in 1954) naming their vibrato systems as "tremolo". Non-vibrato bridges supply an anchoring point for the strings but provide no active control over string tension or pitch. That is, there is no "whammy bar" or lever. A small group of vibrato bridges have an extended tail (also called "longtail"). These guitars have more reverb and sustain in their sound, because of the string resonance behind the bridge. The Fender Jaguar is an example of such a guitar. All bridges have advantages, and disadvantages, depending on the playing style, but, in general, a non-vibrato bridge is thought to provide better tuning stability and a solid contact between the guitar body and the strings. A whammy bar bridge is important in some
heavy metal music Heavy metal (or simply metal) is a Music genre, genre of rock music that developed in the late 1960s and early 1970s, largely in the United Kingdom and United States. With roots in blues rock, psychedelic rock and acid rock, heavy metal band ...
styles, such as shred guitar.


Vibrato bridges

Generally, the more contact the bridge has with the body (i.e., the lower the position), the better the sound transfer is into the body. A "warmer" sound with increased sustain is the result. Vibrato bridges usually must be suspended in some way, which reduces contact. Most vibrato system designs use a group of springs in the guitar body, which oppose the tension of the strings. Some players feel that the vibration of the springs affects
resonance Resonance is a phenomenon that occurs when an object or system is subjected to an external force or vibration whose frequency matches a resonant frequency (or resonance frequency) of the system, defined as a frequency that generates a maximu ...
in a way that makes the guitar sound better, but others disagree. Many electric guitar playing styles require a vibrato system, either "locking" or "non-locking".


Non-locking tremolo/vibrato systems

Non-locking (or vintage) tremolos are the bridges found on guitars manufactured prior to the advent of the Floyd Rose 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 lever used on vintage instruments. However, the "Synchronized Tremolo" type found on the Fender Stratocaster is balanced against a set of screws in much the same manner as a locking tremolo. 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 The Bigsby vibrato tailpiece (or Bigsby for short) is a type of vibrato systems for guitar, mechanical vibrato device for electric guitar designed by Paul Bigsby and produced by the Bigsby Electric Guitar Company (currently an independently oper ...
is another option.


Locking tremolo/vibrato systems

A locking tremolo uses a bridge that has a small clamp in each saddle to hold the strings in place (usually adjusted with an Allen key). The nut at the end fingerboard also clamps the strings to hold them in place. This arrangement is especially useful for playing that requires tapping or heavy "bending" playing styles, such as shred guitar "dive bombing" effects. Locking tremolos provide excellent stability, but their fulcrum points provide minute contact with the body, which might disturb sound transfer.


Non-Tremolo/vibrato 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 bolt directly to the guitar body. Assuming the bridge is of good quality, it limits longitudinal string movement, providing tuning stability. 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 removed. There are no springs in the body or a cavity to accommodate them, which also affects resonance.


See also

*
Fingerboard The fingerboard (also known as a fretboard on fretted instruments) is an important component 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. The stri ...
* Electronic tuner Some tuners attach to the bridge of an instrument. *
Nut (string instrument) A nut, on a stringed musical instrument, is a small piece of hard material that supports the strings at the end closest to the headstock or scroll. The nut marks one end of the vibrating length of each open string, sets the spacing of the strin ...


References

*A.B.Wood (Admiralty Research Laboratory), A Textbook of Sound, Publ Bell, 3rd ed. 1955. No ISBN found.


External links


violinbridges.co.uk Online bridge archive


{{Authority control String instrument construction