The most basic component to the core sound of a guitar is the wood. Different types of wood have different resonant properties called “tonewoods,” which are critical in setting a base for a guitar’s “voice.” A guitar’s sound begins with the transfer of vibrations from its strings into the wood of the guitar: top, body, backs and sides, bridge saddles and fretboards. The wood used on all areas contribute to the sound, and of course these components can be of single- or multi-wood construction. This article will attempt to explain the tonal characteristics in woods most commonly used today.
It should also be noted that woods of the same species but cut from different trees, grown in different regions with different environmental conditions, or the age of the tree, its grain orientation, annular growth patterns and so on, all have an affect on sound. This is mainly because the wood varies in weight, densities, and so on. Therefore, like our species, no two pieces of wood are exactly alike. Furthermore, whether specific woods sound good or bad also partially depends upon who is doing the listening. Distinctions between tonewoods have a relatively subjective point of view and getting to know which is right for you is all part of the magic in searching for your dream guitar.
The top wood, or soundboard of a guitar, to many luthiers is the single overriding variable in determining the quality of tone of the finished instrument.
Spruce is a standard ‘go-to’ material for soundboards. The most commonly used is Sitka spruce. Sitka is a well-rounded tonewood for many styles of playing but excellent for those whose “style demands a wide dynamic response and a robust, meaty tone,” say Dana Bourgeois in his article Tapping Tonewoods. It's known for its tight grain pattern, its high stiffness and relative lightness, translating to a broad dynamic range that stands up well when strummed heartily. At the same time, it’s also quite responsive to fingerpicking, though a light touch may result in a thin sound. Sitka tends to have stronger fundamentals than overtones, and this means that it can sound not quite as robust when played with the lightest touch. Lastly, the break-in period for a new Sitka guitar can also be longer than that of other spruces.
The Engelmann spruce is a common alternative to Sitka however because there is a lower yield than Sitka, Engelmann often costs more. Engelmann is considerably lighter in color than Sitka and lighter in weight and less stiff, resulting in a slightly lower velocity of sound and weaker fundamentals, however, produces a noticeably broader and stronger overtone component. It is a good choice for players who require a richer, more complex tone than can be obtained from most Sitka tops, particularly when the instrument is played softly. Because the Engelmann top has typically less headroom than one made from Sitka, its sound can suffer a little when played loudly.
Sharing a number of characteristics to its cousin, Englemann spruce, Lutz blends the positive characteristics of Sitka and White spruce with the robust tonal output of Adirondack spruce. Taylor Guitar used Lutz spruce, a natural hybrid of Sitka and white spruce when it redesigned its popular 700 series. Mainly because it offers a higher volume ceiling. The Lutz spruce will respond well to a strong attack.
Adirondack, or Eastern red spruce, was the guitar neck tonewood of choice before World War II. But over-harvesting of this wood led to its being all but phased out for use in guitars after the war. Nowadays, Adirondack spruce can be found on select high-end instruments and is relatively heavy and stiff, with a high velocity of sound. It has strong fundamentals, but a greater overtone content than Sitka, and it tends to be the loudest and liveliest of the spruces. Dick Boak of Martin Guitars says “Adirondack can be extremely wide-grained...and not as pretty as other spruces, but it has the uncanny ability to add complexity to the tone.” The red spruce has also been deemed the “Holy Grail of top woods for the steel-string guitar,” by Dana Bourgeois, luthier, writer, lecturer and one of the United States' top acoustic guitar makers.
Though used more frequently in soundboards of the classical guitar, red cedar can make a great steel-string soundboard, ranging in color from honey brown to light chocolate. Its quickness of sound exceeds any of the spruce woods with higher overtones and lower fundamentals and lower stiffness along the grain. Also known for being a bit less bass-y and projective than other spruces. A guitar with cedar top wood is a good choice for a fingerpicker, however, not necessarily good for a strummer with a heavy attack.
Sinker Redwood has a tight grain structure and cross-grain stiffness which produces a stunning, bold sound and brilliant response with rich, warm overtones. It possesses a good balance from bass to mids to trebles. Its rich and strong overtones are similar to Western Red Cedar but crisper. “Well-constructed cedar and redwood guitars can have exceptionally full tonal signatures as well as the balance, responsiveness, and punch of spruce guitars,” says Dana Bourgeois. According to Rick Taylor, famous luthier and founder of Rick Taylor Guitars, Sinker Redwood is like “a cedar on steroids!”
Mahogany and Hawaiian Koa have been used in top woods since the 1920s, but nowadays makers have recently started using maple. What these hard woods have in common are a general low velocity of sound, notable density, low overtones with impressive mid-range tones. “Mahogany-topped guitars exhibit a strong, punchy tone that is well-suited to country blues playing. Koa has a somewhat more mid-rangy tone that works well for rhythm and truly shines in guitars made for Hawaiian-style slide playing,” per Dana Bourgeois.
Maple which is more often used for backs and sides, due to its flatness and relative shortness of decay (an attribute that happens to make the wood more resistant to feedback in amplified situations than rosewood or mahogany), is occasionally used for soundboards. When used in soundboards, Maple carries good tonal qualities and good sustain because it is a very hard wood so the material highlights and amplifies the wood in the body.
The “body” of a guitar or its back and sides, while perhaps not as significant as the soundboard in a guitar’s sound, still needs careful consideration as it can have a tremendous effect on the overall tone of the instrument.
“Rosewood is dense and heavy compared to other woods—almost so heavy that it sinks in water,” Dick Boak of Martin Guitars says, “and it produces extremely warm and resonant tones.”
The precious Brazilian rosewood, native to southeastern Brazil’s Atlantic Forest and used in crafting high-end furniture for centuries, became difficult to source in the last decade or so. In the early 90s, it was added to the CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) treaty, and in 2008, to the federal Lacey Act, which made it impossible to import Brazilian rosewood without a plethora of paperwork and permits. Even special documentation is required to travel with a Brazilian rosewood guitar.
“Nonetheless, some U.S. guitar makers have Brazilian rosewood that pre-dates the ban and so it is still used on costly reissue and boutique guitars,” states Adam Permutter in the October 2016 issue of Acoustic Guitar. Why is Brazilian rosewood so appealing? Beyond its great beauty in its look and deep coloring, it has gorgeous overtones, deep resonance, and excellent sustain. This along with penetrating basses and crystal clear trebles. “Brazilian rosewood is so rich and ring-y, and it has such a big range of workability, that no matter how it’s used it yields pleasing musical results,” Bourgeois says.
Indian rosewood, native to southeast India, is much easier to source than its Brazilian counterpart and that's why it is used in the majority of rosewood guitars today. Indian rosewood is a versatile tonewood, with scooped mids, a deep low-end, and bright high-end and makes a good substitute for Brazilian rosewood. “Indian rosewood has a lot of the same characteristics of Brazilian rosewood—but just a little less of everything,” Bourgeois says.
African Blackwood, a member of the Rosewood family, is harder and denser than Brazilian rosewood as well as ebony, and has long been recognized by classical luthiers as the "holy grail" of body tonewoods. With a strong responsive tap tone, surpassing even that of the Brazilian rosewood some say. It can offer great power, volume, clarity, punch, and harmonic complexity to a guitar. With also a tight, but robust sound and a dark bell-like overtone with slow response. It is truly a unique, exotic wood, similar to Rosewood.
While rosewoods may sound amazing, with its complex overtones and sustain, it can present headaches for a recording engineer. An instrument whose sonic spectrum is cluttered is more difficult to record than one with a comparably direct sound. So, in the studio, mahogany backs and sides can be preferable to rosewood.
Mahogany is a classic ingredient and countless makers have used the wood in both solid and semi-solid designs over the years. It is a fairly dense, medium-to-heavy wood that yields a wide range of guitar-body weights, depending upon stock sources. Used on its own, mahogany’s characteristic tone is warm and somewhat soft, but well balanced with good grind and bite. There is usually good depth to the sound, with full but not especially tight lows, and appealing if unpronounced highs. Mahogany is an excellent wood for solid body guitars and is the primary “go-to” wood for one of our favorite luthiers, Rick Turner. Also used in many acoustic guitars, the Mahogany core gives a warm, vibrant tone that is very desireable for sustain and resonance.
Maple is a great tonewood and extremely versatile. Most North American Maple woods are hard and dense which give the tone a great finish. Bright, alive, and “spanky” are words often used to describe Maple. It's great on electrics as a “cap wood” and it also works very well as an acoustic back and sides wood.
Maple is often used in a multi-wood body, where it is generally partnered with a second, lighter wood. Maple is also one of the most common ingredients of laminates used for semi-hollow electric-guitar bodies, where it contributes tightness and clarity.
Dense and fairly heavy, with characteristics similar to mahogany, walnut is occasionally used in electric-guitar bodies and historically, hasn’t had widespread use among guitar makers. Walnut is however being increasingly used in modern guitars, This tonewood tends to be warm and full, but usually with a firmer low-end, and more overall tightness, Walnut has incredible clarity and sustain.
The harder, denser examples of these woods, such as sugar maple and black walnut- particularly quartersawn examples-tend to lean slightly more toward the tonal direction of mahogany, while softer examples, such as bigleaf maple and claro walnut, tend toward greater tonal transparency.