Acoustic Guitars: Body, Woods, and Voice
English 202C | Lucas Man 10/10/11
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Audience and Scope The target audience is beginner musicians interested in buying an acoustic guitar. Almost everyone who listens to music today has heard the sound of an acoustic guitar. Its prevalence in popular music has led to its popularity amongst first-time musicians. Most of these beginner musicians have an idea of how to play notes with a guitar and a general understanding of its parts, but they do not know the effect of body shape and wood type on the sound produced. The main purpose of this document is to inform the audience about what a guitar’s voice is and what factors contribute to it. The document will describe (1) the different body shapes acoustic guitars come in and (2) the different woods used to make them and compare and contrast their differences. After reading the document, the audience should be able to identify and differentiate between different guitar body shapes and tonewoods and what kinds of sound each make. This type of document would be found in a pamphlet or booklet at a music store that sells guitars.
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Table of Contents
Audience and Scope ...................................................................................................................................... 1 Table of Contents .......................................................................................................................................... 2 The Six-String: A Brief History of the Guitar’s Voice ..................................................................................... 3 What is A Guitar’s Voice?.............................................................................................................................. 4 Body Shapes and What They Mean .............................................................................................................. 5 The Grand Concert .................................................................................................................................... 5 The Grand Auditorium .............................................................................................................................. 5 The Dreadnought ...................................................................................................................................... 6 The Jumbo ................................................................................................................................................. 6 Other Forms .............................................................................................................................................. 6 Cutaways ................................................................................................................................................... 6 Tonewoods and What They Mean ................................................................................................................ 7 Softwoods ................................................................................................................................................. 7 Spruce ................................................................................................................................................... 7 Cedar ..................................................................................................................................................... 7 Hardwoods ................................................................................................................................................ 7 Rosewood.............................................................................................................................................. 7 Mahogany ............................................................................................................................................. 8 Maple .................................................................................................................................................... 8 Other Factors ................................................................................................................................................ 8 Conclusion ..................................................................................................................................................... 8 Sources and References .............................................................................................................................. 10 Picture sources:....................................................................................................................................... 10
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The Six-String: A Brief History Today, acoustic guitars can be heard in almost every genre of music, and they are the backbone instrument of many genres such as rock and country. Its characteristic timbre or voice can be recognized by almost anyone. However, guitars didn’t always look or sound the way they do today. The guitar, in one form or another, has been around for more than a thousand years. It evolved from other plucked string-instruments like the lute and the lyre during the Renaissance period. The first guitars had 4 pairs of strings and were much smaller than even modern classical guitars. The small size of early guitars made them soft, delicate instruments that were overshadowed by louder instruments like the piano during the Renaissance and Baroque periods. The guitar also received little attention in full-orchestra use because of its quietness. In the 19th century, Antonio Torres Jurado, a Spanish guitarist and luthier (some who makes stringed instruments), created the first modern classical guitars, also known as Spanish Figure 1: A Renaissance lute, note the similarities Guitars, with six strings and a larger body. Most modern to a modern classical guitar classical guitar designs are still based on Torres’ original plan. At around the same time that Torres was developing his Spanish guitar, the German immigrant Christian Fredrich Martin was developing his version of a guitar in New York. Guitarists in America had a different vision of the instrument than their European counterparts did. They wanted a louder instrument that could be played alongside other instruments like banjos, mandolins and fiddles, and the animal gut strings at the time could not produce a loud volume. Around 1900, Martin introduced the steel-string guitar, and hence was born the modern acoustic guitar. Steel-strings gave the acoustic guitar the volume and voice to stand on its own as a lead instrument, and the guitar exploded in popularity and went on to revolutionize music.
Figure 2: The Martin & Co. guitar company is one of the oldest steel-string guitar manufacturers and still one of the most renowned today
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What is A Guitar’s Voice? An acoustic guitar’s voice, also called its “sound aesthetic”, is a qualitative description of how the guitar spreads its sound energy between the fundamental frequency and its overtones. The fundamental frequency is the sound wave frequency of the note being played; overtones are sound wave frequencies that are higher than the played note. One guitar might distribute more energy to the fundamental while another might be more overtone-rich. Just like every person has a unique voice, every guitar has a unique voice. Even identical models can sound quite different from each other. Why is this so? Acoustic guitars, in contrast to their electric brethren, are stringed instruments that generate their sound solely from the interactions between its vibrating strings, its body and the air inside and surrounding it. It does not amplify sound in any way; the energy of its vibrating strings is ultimately the only source of sound energy. Figure 3: Parts of an acoustic guitar
The neck of the guitar is where you fret the strings; by pressing the string at different frets, you change the length of the string and alter the frequency of its vibration. This is how different notes are made. However, the neck itself vibrates very little and has little influence over how a guitar sounds. The guitar body is what gives a guitar its characteristic voice and personality. On an acoustic guitar, the strings themselves do not produce much sound at all. Sound is the movement of air, and guitar strings are much too thin to move a large enough volume of air to be heard clearly. So, the strings are stretched over a piece of bone, or some other hard material, called the saddle. The saddle connects the strings to the soundboard—the top piece of wood on the guitar body—and transmits the vibrational energy of the strings to the soundboard and the rest of the Figure 4: The saddle of a guitar being removed, guitar body. saddles are usually made out of bone or another extremely hard material in order to improve energy transfer
The soundboard pushes air both inside and outside of the guitar body and contributes most of the sound that is heard. The back and sides the guitar also vibrate the air inside the body and contribute tones; these vibrations eventually escape out of the sound hole and add complexity to the sound of a guitar. This complex combination of Figure 5: The sound hole of a Taylor guitar where sound from inside the body escapes different tones makes up the voice of the guitar
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Body Shapes and What They Mean The body of an acoustic guitar is the hollow, wooden box that produces the vast majority the guitar’s sound. Acoustic guitars come in a variety of body shapes, and to complicate things even further, different manufacturers sometimes refer to the same shape by different names. Most guitar manufactures offer 4 main body shapes: the grand concert, the grand auditorium, the dreadnought, and the jumbo styles. When describing acoustic guitar bodies, three dimensions are generally used: width of the waist and base, and depth of the base. The width of the waist is the length across the thinnest part of the body, and the width of the base is the length across the widest part, near the bottom of the guitar. The depth of the base is distance between the soundboard and the back of the guitar at its thickest.
1 2
Figure 6: Dimensions of the guitar body: (1) width of waist, (2) width of base and (3) depth of base
3 The Grand Concert
The Grand Concert body shape is an evolution of the traditional classical guitar shape. It is the smallest of the 4 styles and the quietest. It has a very narrow waist and is most comfortable for finger-stylists who prefer to have their guitars on their laps and close to their bodies. The Grand Concert typically has a very clear sound with few overtones. This lack of overtones is also called a “narrow tonal range” and makes the Grand Concert more immune to feedback. Their clear, somewhat sharp sound makes them ideal for recording purposes. The Grand Concert is also sometimes called the Concert, the GC, and the 00 or Figure 7: A nylon-string “Double-Oh” in the case of Martin guitars. Taylor Grand Concert
The Grand Auditorium
guitar, the narrow waist and body are the main feature of this body style
The Grand Auditorium is very similar to the Grand Concert shape. It has the narrow waist of the Grand Concert but a wider and deeper base. The larger volume makes the Grand Auditorium louder and gives it a fuller, more overtone-rich sound. The Grand Auditorium is still relatively small and easy to play on the lap. It is a popular choice for many musicians because of its versatility: it can perform well fingerpicked or strummed, and is clear enough to be used for recording and loud enough for live performances. The Grand Auditorium is also known as the GA, the Auditorium, and the 000 or “Triple-Oh”.
Figure 8: A Taylor Grand Auditorium guitar, it has slightly wider waist and a wider and more rounded base than the Grand Auditorium
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The Dreadnought The Dreadnought is perhaps the most famous of the acoustic guitar shapes. Its waist is almost flush with the top of the guitar and it has a deeper and wider base than the Grand Auditorium. It produces a strong, bass-heavy sound that is preferred by many strummers and flat-pickers in country and rock music. It is also popular with artists who perform live because of its loudness. Due to its size, it can be cumbersome to play on the lap, and the wide waist is less friendly towards fingerstylists.
The Jumbo The Jumbo body shape is a continuation of the Dreadnought’s goal to produce deeper, louder and more bass-heavy sounds out of a guitar. Manufacturers differ on their Jumbo designs, but in general, the Jumbo body shape has a more pronounced waist, and larger, rounder top and base than the Dreadnought. It is the largest and loudest of the 4 forms, and in general it produces the most overtones. Its large size can make it very difficult to play.
Figure 9: A Taylor Dreadnought guitar, note the almost wedge-like shape
Other Forms Figure 10: A Taylor Jumbo guitar, the large size and rounded top and base are its signature features
Some manufacturers offer even more body shapes. Taylor Guitars, for example, has a Grand Symphony body style that incorporates features of the Dreadnought and the Grand Auditorium. Other, more exotic and less standard body shapes also exist. The most common of these less traditional forms is the mini or baby guitar. These are miniature, almost ukulele-sized guitars that still sound like their fullsized brethren.
Cutaways Cutaways are spaces removed from the body of a guitar. They are usually located at the top of the body, near the neck to make it easier for the player to reach the higher frets. Because cutaways reduce the volume of air inside the body and the surface area of the soundboard, they inevitably make the guitar softer. However, this is a trade-off that some guitarists accept.
Figure 11: A Taylor guitar with a cutaway
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Tonewoods and What They Mean Tonewoods are the types of wood that the body of an acoustic guitar is made of, and they are also very influential to the guitar’s sound. Different woods have different strength, density, stiffness, and moisture absorbency. Tonewoods can be divided into two categories: softwoods and hardwoods. The most common woods used for soundboards are softwoods like spruce and cedar. The most common woods used for the back and sides are hardwoods like rosewood, mahogany, and maple. The wood of the soundboard usually play a much larger role in dictating the voice of a guitar than that of the back and sides, which are usually chosen mostly for appearance.
Softwoods Soft woods are typically used for the soundboard because they are lighter and can more effectively transfer the vibrational energy of the strings to air movement. The most commonly used soft woods are spruce and cedar. Spruce Spruces, particularly Engelmann and Sitka spruces are popular soundboard woods because of their stiffness and lightness. Spruces tend to produce crisp, clear sounding tones that give the guitar a bright sound. Figure 12: A sitka spruce soundboard will produce clear, bright tones
Cedar Cedars like the Western Red Cedar are also popular soundboard material. Cedars are less stiff than spruces and so tend to produce softer, mellower tones that give the guitar a warmer and more overtone-rich sound. However, they tend to have a low volume ceiling and are not as loud as spruce. Figure 13: A Western Red Cedar soundboard will produce warm, mellow tones
Hardwoods Hard woods are typically used for the back and sides because of their density, appealing appearance, and durability. The most commonly used hard woods are rosewood, mahogany, and maple. Rosewood Rose wood is arguably the most desired tonewood for the back and sides of guitars. Its deep color and beautiful grain patterns make it highly coveted. It is very dense and durable. It also has an exceptionally long sustain and tends to Figure 14: Indian rosewood is enhance the bass and create rich, bell-like sound. usually dark and has thick, long parallel grain lines
Page |8 Mahogany Mahogany is another popular tonewood and gives a light, dry tone. It can sound more woody and shallow than rosewood. It can come in a variety of colors ranging from pale yellow to brown. Its grain lines are short and scattered.
Maple Maple is a popular choice for tonewoods in a variety of stringed instruments. It produces a clear, bright tone that has a short sustain. Its wide and pronounced grain pattern can create stunning “tiger-stripe” patterns.
Other Factors
Figure 15: Mahogany also has a lighter color and sparser grain pattern
Figure 16: Tiger-stripe pattern on a maple guitar back
Although body shape and type of tonewoods are two of the most basic factors influencing a guitar’s sound, there are other intricacies that can have a major impact as well. A lot of these intricacies lie in manufacturer or luthier preference. For example, small changes in how the soundboard is built and braced can noticeably change how a guitar sounds. These design and build choices are what make a Martin sound different from a Taylor or a Larivée. However, most guitar builders keep their designs and methods a trade secret.
Conclusion The body of an acoustic guitar is what creates the voice of the guitar. A great acoustic guitar’s sound comes from a well-designed body and excellent tonewoods. The shape of the body is the first and most influential factor in shaping a guitar’s voice. Acoustic guitar bodies generally fall into 4 different styles. These are, from smallest to largest, (1) the Grand Concert, (2) the Grand Auditorium, (3) the Dreadnought, and (4) the Jumbo. In general, the larger a guitar’s body is, the louder its sound and the more overtones it will have. The tonewoods of a guitar also shape the guitar’s sound, especially the tonewood of the soundboard. The most common tonewoods for a guitar’s soundboard are spruce, cedar, while rosewood, mahogany, and maple are most commonly used for the back and sides. Other, less visible factors like the bracings on the inside of the body and how each piece of wood is connected to each other also influence the voice of a guitar. In general, these factors are consistent within a single manufacturer or luthier and are what create “the Martin sound” or “the Taylor sound”.
Page |9 However, it is more difficult to pinpoint exactly where the voices of different brands of guitars differ from one another. Spending time listening to guitars from each brand is the only way to gain an appreciation of their differences. At the end of the day, there is only so much science can do to explain why guitars sound the way they do. Musical instruments, like people, are more than the sum of their parts. Knowing just what a guitar is made of and how it is made only goes so far; the best way to understand a guitar is still to play it and enjoy its sounds with your own ears.
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Sources and References http://en.wikipedia.org/wiki/History_of_the_classical_guitar http://en.wikipedia.org/wiki/Steel-string_acoustic_guitar http://www.guitar-maker.com/Pages/histSSG.html http://en.wikipedia.org/wiki/Tonewood http://www.taylorguitars.com/guitars/features/woods/WoodTypes.aspx http://www.taylorguitars.com/guitars/features/shapes/
Picture sources: Cover image by geishaboy500 on Flickr http://www.flickr.com/photos/geishaboy500/3077574029/ Figure 1: http://en.wikipedia.org/wiki/File:ReinassanceLute.jpg Figure 2: by Jeff Cushner on Flickr http://www.flickr.com/photos/13586721@N05/3534943088/ Figure 3: http://www.introductiontoguitar.com/images/acousticdone.jpg Figure 4: http://img3.musiciansfriend.com/dbase/pics/products/6/2/2/369622.jpg Figure 5: http://www.gtrmusic.co.uk/images/products/guitars/used-guitars/taylor-310-ce-ltd-electroacoustic-guitar-soundhole-labell.JPG Figure 6: http://www4.images.coolspotters.com/photos/115559/gibson-1937-l-00-acoustic-guitarprofile.png [arrows and labels added] Figure 7: http://www.taylorguitars.com/guitars/features/shapes/images/photoGC.png [cropped] Figure 8: http://www.taylorguitars.com/guitars/features/shapes/images/photoGA.png [cropped] Figure 9: http://www.taylorguitars.com/guitars/features/shapes/images/photoDN.png [cropped] Figure 10: http://www.taylorguitars.com/guitars/features/shapes/images/photoJumbo.png [cropped] Figure 11: http://www.guitarfriendly.net/wp-content/uploads/2010/06/cutaway.jpg Figure 12: http://www.oregonwildwood.com/Merchant2/_Images2009/Sitka-Spruce-Soundboard.jpg Figure 13: http://www.tsiorba.com/wp-content/themes/tsiorba/order/images/western-red-cedar.jpg Figure 14: http://webpub.allegheny.edu/dept/envisci/ESInfo/comps/phinnen/Rosewood%20wood.jpg Figure 15: http://www.trustile.com/images/wood/mahogany.jpg Figure 16: http://www.earlyromanticguitar.com/erg/pics/G035b-lacote_tigerstripe.jpg
