Steel-string acoustic guitar
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An Aria AW series steel-string acoustic guitar
|Classification||String instrument (plucked)|
(Composite chordophone sounded by a plectrum)
The steel-string acoustic guitar is a modern form of guitar that descends from the classical guitar, but is strung with steel strings for a brighter, louder sound. It is often referred to simply as an acoustic guitar, though the nylon-strung classical guitar is also sometimes called an acoustic guitar.
The standard tuning for an acoustic guitar is E-A-D-G-B-E (low to high), although many players, particularly fingerpickers, use alternate tunings (scordatura), such as "open G" (D-G-D-G-B-D), "open D" (D-A-D-F♯-A-D), or "drop D" (D-A-D-G-B-E).
There are many variations in construction and materials used in steel-string guitars. Different combinations of woods and construction elements (for example, how the top is braced) affect the timbre or "tone" of the guitar. Many players and luthiers feel a well-made guitar's tone improves over time.
Acoustic guitars are commonly constructed in several different body shapes. In general, the guitar's soundbox can be thought of as composed of two connected chambers: the upper bouts and lower bouts (a bout being the rounded corner of an instrument body), which meet at the waist, or the narrowest part of the body face near the soundhole. The proportion and overall size of these two parts helps determine the overall tonal balance and "native sound" of a particular body style – the larger the body, the louder the volume.
- A "00", "Double-Oh" or "Grand Concert" body style is the major body style most directly derived from the classical guitar. It has the thinnest soundbox and the smallest overall size of the major styles, making it very comfortable to play but also one of the quietest. Its smaller size makes it suitable for younger or smaller-framed players. These guitars are commonly called "parlor steels" as they are well-suited to smaller rooms. Martin's 00-xxx series and Taylor's GC series are common examples.
- An "Auditorium" guitar, sometimes called a "000" or "Triple-Oh", is very similar in design to the Grand Concert, but slightly wider and deeper. Many 000-style guitars also have a convex back panel to increase the volume of space in the soundbox without making the soundbox deeper at the edges, which would affect comfort and playability. The result is a very balanced tone, comparable to the 00 but with greater volume and dynamic range and slightly more low-end response, without sacrificing the ergonomics of the classical style, making these body styles very popular. Eric Clapton's signature Martin guitar, for example, is of this style. Martin's 000-xxx series are well-known examples of the Auditorium style.
- A "Dreadnought", arguably the most common body style, incorporates a deeper soundbox, but a smaller and less-pronounced upper bout (the area of the soundbox between the waist and neck) than most styles, giving a somewhat wedge-shaped appearance – hence its name, relating to a class of warship. The dreadnought style was designed by Martin Guitars to produce a deeper sound than "classic"-style guitars, with very present bass fundamentals. This body style's combination of a small profile with a deep sound has made it immensely popular, and it has since been copied by virtually every major steel-string luthier. Martin's "D" series such as the D-28 are classic examples of the dreadnought.
- A "Jumbo" body style is bigger again than a Grand Auditorium but similarly proportioned, and is generally designed to provide a deeper tone, similar to a dreadnought (the body style was designed by Gibson to compete with the dreadnought) but with maximum resonant space for greater volume and sustain. This comes at the expense of being oversized, with a very deep sounding box, and thus somewhat more difficult to play. The foremost example of this style is the Gibson J-200, but like the dreadnought, most guitar manufacturers have at least one jumbo model.
Any of these body styles can optionally incorporate a "cutaway". A cutaway guitar has a redesigned upper bout that removes a section of the soundbox on the underside of the neck, hence the name "cutaway". This allows for easier access to the frets that are located on top of the soundbox past the heel of the neck. The tradeoff is reduced soundbox volume, and often a change in bracing, which can change the resonant qualities and hence the tone of the instrument.
The 12-string guitar replaces each single string with a course of two strings. The lower pairs are tuned an octave apart. This guitar was made famous by Artists such as Lead Belly, Pete Seeger and Leo Kottke.
All of the guitars above are relatively traditional in looks and construction, and are commonly referred to as "flattop" guitars. All are commonly seen and heard in popular music genres, including rock, blues, country, and folk. However, other styles of guitar have been introduced and enjoy moderate popularity, generally in more specific genres:
- The archtop guitar incorporates a top, either carved out of solid wood or heat-pressed using laminations, that is arched like instruments in the violin family, usually with an f-hole rather than a round sound hole. These guitars are most commonly used by swing and jazz players and often incorporate electronics in the form of a pickup. However, many other kinds of acoustic guitars may incorporate these kinds of electronics as well.
- The "Selmer-Maccaferri guitar" is usually played by those who follow the style of Django Reinhardt. It is an unusual-looking instrument, distinguished by a fairly large body with squarish bouts, and either a "D"-shaped or longitudinal oval soundhole. The strings are gathered at the tail like an archtop guitar, but the top is flatter. It also has a wide fingerboard and slotted head like a nylon-string guitar. The loud volume and penetrating tone make it suitable for single-note soloing, and it is frequently employed as a lead instrument in gypsy swing.
- The resonator guitar or resophonic guitar produces sound with one or more metal cones (resonators) instead of the wooden soundboard (guitar top/face). Resonator guitars were originally designed to be louder than conventional acoustic guitars, which were overwhelmed by horns and percussion instruments in dance orchestras. They became prized for their distinctive sound, however, and found life with several musical styles (most notably bluegrass and also blues) well after electric amplification solved the issue of inadequate guitar sound levels.
Traditionally, steel-string guitars have been made of a combination of various "tonewoods", or woods that have pleasing resonant qualities when used in instrument-making. Foremost are Sitka spruce, the most common, and Alpine and Adirondack spruce, the most sought-after, woods for the making of guitar tops. The back and sides of a particular guitar are typically made of the same wood; Brazilian or East Indian rosewood and Honduras mahogany are traditional choices, however, maple has been prized for the figuring that can be seen when it is cut in a certain way (such as "flame" and "quilt" patterns). A common non-traditional wood gaining popularity is sapele, which is tonally similar to mahogany but slightly lighter in color and possessing a deep grain structure that is visually appealing.
Due to decreasing availability and rising prices of premium-quality traditional tonewoods, many manufacturers have begun experimenting with alternative species of woods or more commonly available variations on the standard species. For example, some makers have begun producing models with redcedar or mahogany tops, or with spruce variants other than Sitka. Cedar is also common in the back and sides, as is basswood. Entry-level models, especially those made in East Asia, often use nato wood, which is again tonally similar to mahogany but is cheap to acquire. Some have also begun using non-wood materials, such as plastic or graphite. Carbon-fiber and phenolic composite materials have become desirable for building necks, and at least one high-end luthier (Composite Acoustics) produces a line of all-carbon-fiber guitars, prized for their high stability in changing climates that would cause wood instrument panels to swell and shrink.
The steel-string acoustic guitar evolved from the nylon- or gut-string classical guitar, and because steel strings have higher tension, heavier construction is required overall. One innovation is a metal bar called a truss rod, which is incorporated into the neck to strengthen it and provide adjustable counter-tension to the stress of the strings. Typically, a steel-string acoustic guitar is built with a larger soundbox than a standard classical guitar. A critical structural and tonal component of an acoustic guitar is the bracing, a systems of struts glued to the inside of the back and top. Steel-string guitars use different bracing systems from classical guitars, typically using X-bracing instead of fan bracing. (Another simpler system, called ladder bracing, where the braces are all placed across the width of the instrument, is used on all types of flat-top guitars on the back.) Innovations in bracing design have emerged, notably the A-brace developed by British luthier Roger Bucknall of Fylde Guitars.
Most luthiers and experienced players agree that a good solid top (as opposed to laminated or plywood) is the most important factor in the tone of the guitar. Solid backs and sides can also contribute to a pleasant sound, although laminated sides and backs are acceptable alternatives, commonly found in mid-level guitars (in the range of US$300–$1000).
From the 1960s through the 1980s, "by far the most significant developments in the design and construction of acoustic guitars" were made by the Ovation Guitar Company. It introduced a composite "roundback" bowl, which replaced the square back and sides of traditional guitars; because of its engineering design, Ovation guitars could be amplified without producing the obnoxious feedback that had plagued acoustic guitars before. Ovation also pioneered with electronics, such as pickup systems and electronic tuners.
See Guitar for more details on the construction of acoustic guitars.
A steel-string guitar can be amplified with a:
- microphone, possibly clipped to the guitar body;
- detachable pickup, often straddling the soundhole and using the same magnetic principle as a traditional electric guitar; or
- transducer built into the body.
The last type of guitar is commonly called an "acoustic-electric" or "electro-acoustic" guitar, as it can be played either "unplugged" as an acoustic or plugged in as an electric. The most common type is a piezoelectric pickup, which is composed of a thin sandwich of quartz crystal. When compressed, the crystal produces a small electrical current, so when placed under the bridge saddle, the vibrations of the strings through the saddle, and of the body of the instrument, are converted to a weak electrical signal. This signal is often sent to a pre-amplifier, which increases the signal strength and normally incorporates an equalizer. The output of the preamplifier then goes to a separate amplifier system similar to that for an electric guitar.
Several manufacturers produce specialised acoustic guitar amplifiers, which are designed to give undistorted and full-range reproduction.
Music and players 
Until the 1960s, the predominant forms of music played on the flat-top, steel-string guitar remained relatively stable and included acoustic blues, country, bluegrass, folk, and several genres of rock. The concept of playing solo steel-string guitar in a concert setting was introduced in the early 1960s by such performers as Davey Graham and John Fahey, who used country blues fingerpicking techniques to compose original compositions with structures somewhat like European classical music. Fahey contemporary Robbie Basho added elements of Indian classical music and Leo Kottke used a Faheyesque approach to make the first solo steel-string guitar "hit" record.
Steel-string guitars are also important in the world of flatpicking, as utilized by such artists as Clarence White, Tony Rice, Bryan Sutton, Doc Watson and David Grier. Luthiers have been experimenting with redesigning the acoustic guitar for these players. These flat-top, steel-string guitars are constructed and voiced more for classical-like fingerpicking and less for chordal accompaniment (strumming). Some luthiers have increasingly focused their attention on the needs of fingerstylists and have developed unique guitars for this style of playing.
Many other luthiers attempt to recreate the guitars of the "Golden Era" of C.F. Martin & Co. This was started by Roy Noble, who built the guitar played by Clarence White from 1968 to 1972, and was followed by Bill Collings, Marty Lanham, Dana Bourgeois, Randy Lucas, Lynn Dudenbostel and Wayne Henderson, a few of the luthiers building guitars today inspired by vintage Martins, the pre–World War II models in particular. As prices for vintage Martins continue to rise exponentially, upscale guitar enthusiasts have demanded faithful recreations and luthiers are working to fill that demand.
See also 
- http://www.sweetwater.com/shop/guitars/acoustic/buying-guide.php Sweetwater Music - Acoustic Guitar Buying Guide
- , p. 48 Text "Denyer" ignored (help); Text "1989" ignored (help); Missing or empty
|title=(help): Denyer, Ralph (1992). "Ovation guitars (Acoustic guitars)". The guitar handbook. Special contributors Isaac Guillory and Alastair M. Crawford (Fully revised and updated ed.). London and Syndey: Pan Books. p. 48. ISBN 0-330-32750-X. Unknown parameter
- Anonymous, Music Trades (1 October 2004). "Ovation's encore: How a host of product refinements have rekindled growth at Kaman Music's flagship guitar division". The Music Trades. The Guitar Market. (subscription required). Retrieved 1 May 2012. Text "." ignored (help)
- Carter, Walter (1996). Eiche, Jon, ed. The history of the Ovation guitar. Musical Instruments Series (first ed.). Milwaukee, Wisconsin: Hal Leonard Corporation. pp. 1–128. ISBN 978-0-7935-5876-6, ISBN 0-7935-5876-X (softcover), ISBN 0-7935-5948-0 (hardcover) Check
|isbn=value (help). HL00330187.
- Cruice, Valerie (December 8 1996). "From the ratcheting of helicopters to a guitar's hum". The New York Times.
- Marks, Brenda (30–31 May 1999). "Connecticut firm makes guitars, helicopter blades from same fiberglass". Waterbury Republican-American (New Hartford, Conn.: Knight Ridder/Tribune Business News). (subscription required). Retrieved 24 April 2012.