Guitar bracing refers to the system of wooden struts which internally support and reinforce the
soundboard and back of
acoustic guitars
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, ...
.
Soundboard or top bracing transmits the forces exerted by the strings from the
bridge
A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...
to the rim. The
luthier
A luthier ( ; AmE also ) is a craftsperson who builds or repairs string instruments that have a neck and a sound box. The word "luthier" is originally French and comes from the French word for lute. The term was originally used for makers o ...
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
A sound box or sounding box (sometimes written soundbox) is an open chamber in the body of a musical instrument which modifies the sound of the instrument, and helps transfer that sound to the surrounding air. Objects respond more strongly to vibr ...
.
Materials
Braces may be made from top woods (spruce or cedar), balsa wood or, in high-end instruments,
carbon fiber
Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers (Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon compo ...
composites.
Nylon string guitar bracing
Fan bracing
This is the standard bracing pattern on the
classical guitar
The classical guitar (also known as the nylon-string guitar or Spanish guitar) is a member of the guitar family used in classical music and other styles. An acoustic wooden string instrument with strings made of gut or nylon, it is a precursor o ...
, dating to the work of
Antonio Torres Jurado
Antonio de Torres Jurado (13 June 1817 – 19 November 1892) was a Spanish guitarist and luthier, and "the most important Spanish guitar maker of the 19th century."
It is with his designs that the first recognisably modern classical guitars a ...
in the 19th century. Although the originator of this bracing style has not been reliably established, the earliest known use is by Spanish luthier Francisco Sanguino in the mid to late 18th century.
Kasha Bracing
In the 1970s, scientist
Michael Kasha
Michael Kasha (December 6, 1920 – June 12, 2013) was an American physical chemist and molecular spectroscopist who was one of the original founders of the Institute of Molecular Biophysics at Florida State University .
Education and early wo ...
radically overhauled every aspect of guitar design to incorporate principles such as
mechanical impedance matching.
Lattice bracing
The Australian guitarmaker
Greg Smallman
Greg Smallman (born 19 June 1947 in Cronulla, Australia) is the first internationally successful non-traditional Australian guitar-maker. He is known worldwide for his innovative guitar designs[John Williams
John Towner Williams (born February 8, 1932)Nylund, Rob (15 November 2022)Classic Connection review ''WBOI'' ("For the second time this year, the Fort Wayne Philharmonic honored American composer, conductor, and arranger John Williams, who wa ...]
.
Smallman's design was inspired by research by Torres who made a guitar with a
papier mâché
Papier may refer to :
*paper in French, Dutch, Afrikaans, Polish or German, word that can be found in the following expressions:
**Papier-mâché, a construction material made of pieces of paper stuck together using a wet paste
**Papier collé, a p ...
back and sides to show that the soundboard was the most important factor in guitar sound projection. Smallman also uses two 45 degree pole supports in the frame running from the bottom of the guitar to the waist to prevent the string tension from distorting the body and sound board.
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-built tops are less responsive. Braces are usually made from Sitka Spruce (
Picea sitchensis
''Picea sitchensis'', the Sitka spruce, is a large, coniferous, evergreen tree growing to almost tall, with a trunk diameter at breast height that can exceed 5 m (16 ft). It is by far the largest species of spruce and the fifth-larg ...
). Some luthiers use Adirondack Spruce, also known as "Red Spruce" (
Picea rubens
''Picea rubens'', commonly known as red spruce, is a species of spruce native to eastern North America, ranging from eastern Quebec and Nova Scotia, west to the Adirondack Mountains and south through New England along the Appalachians to western ...
), 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 Martin
Christian Frederick Martin Sr. (german: Christian Friedrich Martin I.; January 31, 1796 – February 16, 1873) was a German-born American luthier who specialized in guitars and the founder of C. F. Martin & Company. He made the first guitar in ...
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 guitar
A twelve-string guitar (or 12-string guitar) is a steel-string guitar with 12 strings in six courses, which produces a thicker, more ringing tone than a standard six-string guitar. Typically, the strings of the lower four courses are tuned in o ...
s.
This bracing does not allow the top to move or vibrate as much as it normally would but offers more strength and prevent bellying around the bridge area.
A-bracing
Several bracing styles are designated as A-bracing. ''Mottola's Cyclopedic Dictionary of Lutherie Terms'' lists two. The first, typical of instruments built by Tacoma, use two long longitudinal struts that diverge from near the neck block to near the tail end of the guitar. This bracing style is used on instruments that feature a soundhole that is not centrally located. The second style listed is that used by some models of Ovation guitars, also called Adamas bracing. There is also a variation on X-bracing called A-bracing. The X-shaped structure under the bridge is retained, but the transverse
strut between 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 ...
and
soundhole
A sound hole is an opening in the body of a stringed musical instrument, usually the upper sound board.
Sound holes have different shapes:
* round in flat-top guitars and traditional bowl-back mandolins;
* F-holes in instruments from the vio ...
is replaced by two diagonal braces which splay outward going toward the soundhole. It is used by Lowden Guitars.
V-Class Bracing
V-Class bracing is a bracing style developed by Andy Powers for Taylor Guitars. It is similar to A-bracing, however the main braces diverge across both sides of the sound hole towards the neck side of the top, and converge at the endblock to form the shape of a V. A lateral brace positioned between the soundhole and bridge plate spans the width of the top, and there are two sets of tone/finger braces between the bridge plate and endblock that are roughly perpendicular to the longitudinal V-braces and run from the V-brace towards the edge of the top. It is purported to allow the top to be both stiff and flexible in order to produce more volume and sustain. Taylor also purports that the design improves harmonic intonation.
Falcate bracing
Falcate(sickle-shaped) bracing is a symmetric bracing style designed by luthier and engineer Trevor Gore, and used on his steel-string and classical nylon-string guitars. It claims a more even sound over the frequency spectrum, and more responsiveness and volume without being too delicate.
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 scalloped 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 guitar
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."
Image:Steel_String_X-bracing1.jpg, Plan view of top bracing
Image:Steel_string_guitar_X-bracing_system2.jpg, Note the parabolic shape of the lower arm treble X-brace and the scalloped shape on the opposite side.
Image:Top_bracing_3.jpg, Top fitted to rim. Note the scalloped vintage style brace carving on this model.
Ladder bracing
This simple system, where braces are arranged parallel to each other and perpendicular
to the direction of the strings, is employed on most guitar backs. The earliest steel string guitars very often had ladder braced tops, a practice which survives in the
Maccaferri guitar
The Selmer guitar — often called a Selmer-Maccaferri or just Maccaferri by English speakers, as early British advertising stressed the designer rather than manufacturer — is an unusual acoustic guitar best known as the favored inst ...
. It is considered more suitable for parlor guitars and lightly strung instruments.
Image:Back_bracing2.jpg, Ladder bracing
Archtop bracing
Archtop guitar
An archtop guitar is a hollow electric or semi-acoustic guitar with a full body and a distinctive arched top, whose sound is particularly popular with jazz, blues, and rockabilly players.
Typically, an archtop guitar has:
* Six strings
* An ar ...
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 is an American company that manufactures musical instruments. The company was founded in 1883 in Brooklyn, New York by Friedrich Gretsch, a 27-year-old German immigrant, shortly after his arrival to the United States. Friedrich Gretsc ...
archtops
Trestle bracing
/ref>
References
{{DEFAULTSORT:Bracing Styles For Steel String Acoustic Guitars
Guitars