An Aria AW series steel-string acoustic guitar |
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| String instrument | |
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| Classification | String instrument (plucked) |
| Hornbostel–Sachs classification | 321.322-6 (Composite chordophone sounded by a plectrum) |
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A steel-string acoustic guitar is a modern form of guitar descended from the classical guitar, but strung with steel strings for a brighter, louder sound. It is often referred to simply as an acoustic guitar, although strictly speaking the nylon-strung classical guitar is acoustic as well.
The most common type can be called a flat-top guitar to distinguish it from the more specialized archtop guitar and other variations.
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).
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There are many different variations on the construction of, and materials used in, steel-string guitars. The various combinations of the different woods and their quality, along with design and construction elements (for example, how the top is braced), are among the factors affecting 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 being composed of two connected chambers: the "upper bout" and "lower bout", 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.
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.
Another variation on the standard acoustic guitar is the 12-string guitar, which sports an additional, doubling string for each of the traditional six strings. This guitar was made famous by artists such as Lead Belly, Pete Seeger and Leo Kottke.
All of the above guitars 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:
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).
A unique construction method is that of Ovation Guitar Company, which uses a rounded one-piece composite plastic bowl for the back and sides of virtually all of its guitars (the top and neck are usually still wood, though newer models have introduced phenolic necks). The resulting instrument is relatively durable, and the materials costs and luthier's labor drastically reduced; however, the tone of such a guitar is different from one with an all-wood soundbox.
Electronics, such as pickup systems and electronic tuners, may be installed in modern instruments.
See Guitar for more details on the construction of acoustic guitars.
Guitars can be factory-built or made in smaller operations focusing on handcrafting and tailoring to individual customers' requirements. The latter are often referred to as luthiers.
There are several prominent American makers of steel-string acoustic guitars. Breedlove, Collings, Gibson, Guild, Martin and Taylor are known for both the quality and price of their instruments. Other less-recognized but popular North American luthier shops include Godin and Larrivée, both based in Canada. In Europe, several steel-string acoustic guitar makers have gained a worldwide reputation, although their production output is small relative to U.S. and Asian makers. Among the leading European brands are Avalon and Tanglewood.
Many prominent, quality East Asian brands have been introduced to the U.S. and are popular with players of many skill levels. Yamaha produces a large assortment of musical instruments; while Cort, Ibanez, Ovation and Takamine are other popular Korean/Japanese companies which specialize in guitar-making. Alvarez Guitars, another quality brand, are made in China or Japan. In addition, many traditionally U.S.-centered brands have outsourced the production of their low-cost models to Asian firms: Fender/Squier and Gibson/Epiphone all own or contract with Asian factories to produce many of their entry-level and even intermediate-level instruments.
In Australia top-end guitars are manufactured by Cole Clark and Maton.
A steel-string guitar can be amplified with a:
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.
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.
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