Guitar bracing
Encyclopedia
Guitar bracing refers to the system of wooden struts which support and reinforce the soundboard and back of the instrument.
Soundboard or top bracing transmits the forces exerted by the strings from the bridge to the rim. The luthier faces the challenge of bracing the instrument to withstand the stress applied by the strings with minimal distortion, while permitting the top to respond as fully as possible to the tones generated by the strings. Brace design contributes significantly to the type of sound a guitar will produce. According to luthiers W. Cumpiano and J. Natelson, "By varying brace design, each builder has sought to produce a sound that conformed to his concept of the ideal."
The back of the instrument is braced to help distribute the force exerted by the neck on the body, and to maintain the tonal responsiveness and structural integrity of the sound box.
, dating to the work of Antonio Torres Jurado
in the 19th century.
radically overhauled every aspect of guitar design to incorporate principles such as mechanical impedance matching.
introduced guitars with an extremely thin soundboard, which is supported by bracing in the shape of a lattice. Smallman combines this with heavier, laminated back and sides with a frame. Smallman's guitars are used by John Williams
.
between 1840 and 1845 for use in gut string guitars.
The system consists of two braces forming an X shape across the soundboard below the top of the sound hole. The lower arms of the X straddle and support the ends of the bridge. Under the bridge is a hardwood bridge plate which prevents the ball end of the strings from damaging the underside of the soundboard. Below the bridge patch are one or more tone bars which support the bottom of the soundboard. These abut one of the X braces and usually slant down towards the bottom edge of the soundboard. The top tone bar butts against a portion of the bridge patch in most instruments. Above the sound hole a large transverse brace spans the width of the upper bout of the soundboard. Around the lower bout, small finger braces support the area between the X-braces and the edge of the soundboard.
s.
strut between the fingerboard
and soundhole is replaced by two diagonal braces which splay outward going toward the sound hole.
with smooth mids and crisp highs. Parabolic braces will yield a quick response with a more pronounced mid range and a more focused bottom end."
to the direction of the strings, is employed on most guitar backs. It was also once used
on guitar tops, a practice which survives in the Maccaferri guitar. It is considered more suitable for archtops and lightly strung instruments.
s originally had two near-horizontal braces or "tone bars" on either side from bridge to neck, a system known as parallel bracing. The braces roughly run under the feet of the archtop guitar's bridge. X-bracing, similar to that of flat-top guitars was later introduced. Their tops are inherently stronger than flat tops, so less bracing may be required. "Trestle" bracing was a system used on some Gretsch
archtops
Soundboard or top bracing transmits the forces exerted by the strings from the bridge to the rim. The luthier faces the challenge of bracing the instrument to withstand the stress applied by the strings with minimal distortion, while permitting the top to respond as fully as possible to the tones generated by the strings. Brace design contributes significantly to the type of sound a guitar will produce. According to luthiers W. Cumpiano and J. Natelson, "By varying brace design, each builder has sought to produce a sound that conformed to his concept of the ideal."
The back of the instrument is braced to help distribute the force exerted by the neck on the body, and to maintain the tonal responsiveness and structural integrity of the sound box.
Materials
Braces may be made from top woods (spruce or cedar), balsa wood or, in high-end instruments, carbon fibre composites.Fan bracing
This is the standard bracing pattern on the classical guitarClassical guitar
The classical guitar is a 6-stringed plucked string instrument from the family of instruments called chordophones...
, dating to the work of Antonio Torres Jurado
Antonio Torres Jurado
Antonio de Torres Jurado was a Spanish guitarist and luthier, and "the most important Spanish guitar maker of the 19th century."...
in the 19th century.
Kasha Bracing
In the 1970s, scientist Michael KashaMichael Kasha
Michael Kasha is an American physical chemist and molecular spectroscopist who is one of the original founders of the Institute of Molecular Biophysics at Florida State University . Born in Elizabeth, NJ to a family of Ukrainian immigrants, he earned his Ph.D...
radically overhauled every aspect of guitar design to incorporate principles such as mechanical impedance matching.
Lattice bracing
The Australian guitarmaker Greg SmallmanGreg Smallman
Greg Smallman is an Australian luthier known worldwide for his innovative guitar designs. Although his guitars are in outward appearance similar to a traditional Spanish classical guitar, there are numerous innovative differences. Among them is the use of a high, arched and carved back for the...
introduced guitars with an extremely thin soundboard, which is supported by bracing in the shape of a lattice. Smallman combines this with heavier, laminated back and sides with a frame. Smallman's guitars are used by John Williams
John Williams (guitarist)
John Christopher Williams is an Australian classical guitarist, and a long-term resident of the United Kingdom. In 1973, he shared a Grammy Award win in the 'Best Chamber Music Performance' category with Julian Bream for Julian and John .-Biography:John Williams was born on 24 April 1941 in...
.
Steel string flat-top guitar bracing
In all steel-string instruments the ends of the top braces taper at the edge of the soundboard. In most factory built guitars the brace tops are given a round profile, but are otherwise left unshaped. This produces a stronger top and may reduce the number of warranty claims arising from damage, however, over-build tops are less responsive. Braces are usually made from Sitka Spruce (Picea sitchensis). Some luthiers use Adirondac Spruce, also known as Red Spruce (Picea rubens), in high end instruments.X-Bracing
The tops of most steel string acoustic guitars are braced using the X-brace system, or a variation of the X-brace system, generally attributed to Christian Frederick MartinChristian Frederick Martin
Christian Frederick Martin, Sr. was a luthier who specialized in guitars.Born in Markneukirchen, Germany to a family of cabinet makers, Martin became an apprentice of the guitar maker Johann Georg Stauffer of Vienna, Austria....
between 1840 and 1845 for use in gut string guitars.
The system consists of two braces forming an X shape across the soundboard below the top of the sound hole. The lower arms of the X straddle and support the ends of the bridge. Under the bridge is a hardwood bridge plate which prevents the ball end of the strings from damaging the underside of the soundboard. Below the bridge patch are one or more tone bars which support the bottom of the soundboard. These abut one of the X braces and usually slant down towards the bottom edge of the soundboard. The top tone bar butts against a portion of the bridge patch in most instruments. Above the sound hole a large transverse brace spans the width of the upper bout of the soundboard. Around the lower bout, small finger braces support the area between the X-braces and the edge of the soundboard.
Double X-bracing
In this system, two overlapping X shapes form a diamond surrounding the underside of the bridge plate. Some luthiers prefer it where additional strength is required, for instance for twelve string guitarTwelve string guitar
The twelve-string guitar is an acoustic or electric guitar with 12 strings in 6 courses, which produces a richer, more ringing tone than a standard six-string guitar...
s.
A-bracing
This is a variation on X-bracing. The X-shaped structure under the bridge is retained, but the transversestrut between 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...
and soundhole is replaced by two diagonal braces which splay outward going toward the sound hole.
Brace shape and 'voicing' or 'tap tuning'
Luthiers building higher quality instruments adjust the stiffness of the top and shape the braces to maximize the response of the top while maintaining structural integrity. Tone bars and bottom halves of the X-braces may be either scolloped or parabolic in shape. Above the X-brace joint, braces usually have a parabolic shape. Experienced luthiers 'voice' or 'tap-tune' the tops and backs of high end guitars to produce optimum tone and responsiveness in the hands of the player.Scalloped vs parabolic bracing
Bracing style and shape will affect the tone of the instrument. According to luthiers Bob Connor and David Mainwaring, "scalloped braces will produce a warmer sounding bass response in the guitarwith smooth mids and crisp highs. Parabolic braces will yield a quick response with a more pronounced mid range and a more focused bottom end."
Ladder bracing
This simple system, where braces are arranged parallel to each other and perpendicularto the direction of the strings, is employed on most guitar backs. It was also once used
on guitar tops, a practice which survives in the Maccaferri guitar. It is considered more suitable for archtops and lightly strung instruments.
Archtop bracing
Archtop guitarArchtop guitar
An archtop guitar is a steel-stringed acoustic or semi-acoustic guitar with a full body and a distinctive arched top, whose sound is particularly popular with blues and jazz players.Typically, an archtop guitar has:* 6 strings...
s originally had two near-horizontal braces or "tone bars" on either side from bridge to neck, a system known as parallel bracing. The braces roughly run under the feet of the archtop guitar's bridge. X-bracing, similar to that of flat-top guitars was later introduced. Their tops are inherently stronger than flat tops, so less bracing may be required. "Trestle" bracing was a system used on some Gretsch
Gretsch
The Gretsch Company was founded in 1883 by Friedrich Gretsch, a twenty-seven year old German immigrant recently arrived in the US. Friedrich Gretsch manufactured banjos, tambourines, and drums, until his death in 1895. His son, Fred, moved operations to Brooklyn, New York in 1916...
archtops