- Question: What is a “tonewood?”.
- Simple answer: Any wood used to generate a musical tone.
The acoustic guitar is capable of producing musical sound primarily as a result of the kinetic energy of it’s vibrating strings traveling across the soundboard (aka top or front plate). The roles played by the rest of the components that make up the guitar (back, sides and neck) are affected by how the instrument is constructed. Traditionally, acoustic guitars have been built much like speaker cabinets having very, very rigid (fixed, stationary) backs. Sound is generated primarily (if not solely) by the soundboard, with the backs playing more of a structural role and, to a much lesser degree, perhaps even acting as a reflector. Uncoupling the backs from that rigid design, allowing them to move more freely (or resonate at lower frequencies), encourages a greater interaction between the two plates (front and back) and may place a greater significance on the wood selection / combination. The front and back plates of the acoustic guitar are held apart by the sides which, in keeping with tradition, are commonly selected to match the back woods. This choice is mostly for visual appeal / continuity, as there appears to be no acoustical benefit derived from using the same wood. All three components (the soundboard, the back and the sides) are assembled together to comprise the body of the guitar. The neck of the instrument is attached to the body using glue (for a more permanent bond) or bolts (for easy removal). The strings are anchored at the end of the neck farthest away from the body (the headstock) and are secured to the body via the bridge, an external brace that is glued to the soundboard. A fretboard (or fingerboard) lies beneath the strings and is attached to the front surface of the neck. The woods selected for these components are commonly referred to as tonewoods.
Guitar makers often construct acoustic guitar bodies using softwoods for the soundboards (such as Spruce or Cedar) and hardwoods for the backs and sides (such as Rosewood, Mahogany, Maple or any number of so-called exotic woods). Over the years, adventurous luthiers have explored the depths of wood resources and combinations. Today it is not unusual to see guitar bodies made using all hardwoods (such as Koa, Mahogany, or Myrtle) or even all softwoods (such as Douglas Fir).
By strict definition, only a few woods are capable of independently producing what we would generally consider to be musical tone. Those that can are often said to have a vitreous or glass-like quality where, when struck, the sound they generate is likened to the ringing of a bell or gong. A well-known example of such a tonewood is Brazilian Rosewood, traditionally used to construct the marimba, a percussion instrument made up of wooden bars that are struck with a mallet. Metal pipes suspended below the bars amplify the resonant frequencies. The size of the piece of wood alone determines the pitch of the note, while the traits and characteristics of the wood determines it's tone. Wider, longer bars of Rosewood reproduce lower notes, while narrower, shorter bars are responsible for higher notes. See my article titled, “Wood is Wood...Until it is More” for a video featuring the marimba. Not surprisingly, the most common woods used in guitar construction, the Rosewoods, Cedars, Spruces, Redwood, etc., also happen to be considered true tonewoods.
Another understanding of the term tonewood applies to any wood used in the construction of a guitar. The overall sound of a given instrument is generally acknowledged to be the sum of it’s parts. Curiously, unlike a wood that rings like a bell when struck, a wood that simply goes thud! or thunk! may be incorporated into an instrument that sounds surprisingly good when played. (NOTE: This understanding lends credence to the belief that the design and construction of the guitar may play an even more significant role in the resultant musicality of the finished instrument than does the particular selection of the wood(s). See my article titled, “Handcrafted vs Factory-built” for more on this topic.)
“Coaxing maximum musicality out of the design, construction and materials is my understanding of the art of lutherie.” — Christopher Cozad
The cellular structure of a given wood determines it’s distinctiveness, both visually and tonally. Much like wine produced from grapes, guitars built from various species of wood can have definable characteristics. Just as a fine Pinot Noir wine is measurably different from a Cabernet Sauvignon regardless of how it is produced so, typically, is Indian Rosewood measurably different from Claro Walnut, regardless of how the guitar is constructed. However, two vinters may produce two distinguishable wines using the very same grape by altering their harvesting or fermenting technique(s). In the same way, two luthiers can produce two distinct guitars using the same wood, but altering their build methods. Debating the degree to which the senses can be trained to identify subtle variations in wine or food, let alone wood, is not the objective of this article, nor does this luthier believe it necessary to score perfectly in some blind Tonewood Identification Listening Test (B-TILT™ -LOL-) in order to appreciate one wood over another.
The characteristics associated with various wood species should not be confused with wood quality, nor should these characteristics be relied upon solely to determine the sonic potential of a given guitar. I believe that, in the right hands, measurable factors such as volume, mass, density, and modulus of elasticity (a given wood’s resistance to being deformed when force is applied) play the more significant roles in the overall tone and responsiveness of an acoustic guitar, and should be the determining factors when selecting wood. But that is a topic for another article.
- Janka hardness: 510 lb f
- Average Dried Weight: 27 lbs/ft 3
- Modulus of Elasticity: 11.03 GPa
Sitka Spruce is a softwood known for having a very high stiffness (or strength) to weight ratio, both across-the-grain and along-the-grain, making it a popular all-around choice for guitar soundboards. This tree is native to the Pacific coast of North America in forests ranging from Oregon to Alaska and has been measured having heights greater than 300 ft. Colors range from off-white to pale yellow and, while being straight grained, variations known as bear claw can be visually stunning. With so many guitars being made over the decades having soundboards of Sitka Spruce, this softwood has become something of a benchmark by which other tonewoods are compared.
- Janka hardness: 350 lb f
- Average Dried Weight: 23 lbs/ft 3
- Modulus of Elasticity: 7.66 GPa
Though soft enough to dent with a fingernail, WRC can match or exceed Spruce in it’s stiffness to weight ratio, though this stiffness is typically notable along the grain only. This may explain why WRC can be “overdriven” more readily than Spruce, and is sometimes avoided by more aggressive players. WRC is lighter than the Spruces, so a WRC soundboard can be left a bit thicker to compensate for it’s shortcomings in across-the-grain stiffness. The Western Redcedar is native to Oregon, Washington and British Columbia with smaller forests found in parts of Idaho, Montana and Alberta. It is a magnificent tree growing to heights of 200 ft. and often reaching ages of 1000 years or more. Reddish-brown to brown in color with straight grain.
- Janka hardness: 450 lb f
- Average Dried Weight: 26 lbs/ft 3
- Modulus of Elasticity: 8.41 GPa
The largest of the evergreens, the Redwood (or Sequoia - both terms are accurate) can attain heights of nearly 380 ft. and is native to southern Oregon extending as far south as central California. The tallest tree in the world, Sequoia sempervirens, and the largest tree in the world (by volume), Sequoiadendron giganteum, are both Redwoods, though the latter is sometimes referred to as Giant Sequoia. The reddish hue and distinctive fragrance of the lumber of this tree make it easily recognizable. Wood from felled, older trees is desirable for it’s increased cross-grain stiffness. Commonly straight grained, figured or flamed Redwood is quite beautiful in appearance.
- Janka hardness: 620 lb f
- Average Dried Weight: 32 lbs/ft 3
- Modulus of Elasticity: 12.17 GPa
Heavier than Spruce, Cedar and Redwood, yet possessing one of the highest stiffness to weight ratios of all the softwoods, Douglas Fir is an often overlooked tonewood. This mighty tree, at 330 ft. is exceeded in height only by the Coast Redwood. Douglas Fir forests range from central British Columbia to central Mexico, extending eastward as far as west Texas. Color ranges from pale yellow to reddish-tan, and the grain is straight. While this wood is typically not as aesthetically pleasing as one of the Spruces, and is a bit heavier, it is definitely worthy of consideration.
Port Orford Cedar
- Janka hardness: 590 lb f
- Average Dried Weight: 29 lbs/ft 3
- Modulus of Elasticity: 11.35 GPa
Lighter than Douglas Fir, yet as stiff if not occasionally stiffer, the highly aromatic Port Orford Cedar is actually a Cypress. Reaching heights of 200 ft., these trees can be found along the coast of southern Oregon and northern California. Tonally, Port Orford Cedar sits comfortably between Sitka Spruce and Western Redcedar. Paler in color that Western Redcedar, this relatively straight-grained tonewood can also sport curl, a particularly stunning variation. And did I mention that it smells great?
- Janka hardness: 850 lb f
- Average Dried Weight: 34 lbs/ft 3
- Modulus of Elasticity: 10.0 GPa
The leaves of the Bigleaf Maple can easily span 12", hence it’s name. These trees are found in the Pacific coastal region of North America, ranging from southern California to Alaska’s southern border. The largest of these trees resides in Oregon and measures 8 feet in diameter and 88 feet tall. Softer than Rock or Sugar Maple, Bigleaf is sometimes referred to as Quilted or Curly, Tiger, Flamed or Fiddleback Maple due to the prevalence of a couple of 3-D phenomena that can occur in the grain pattern. When present, flatsawing will reveal the quilted pattern, where quartersawing is necessary to reveal the curl (Curly, Tiger, Flamed, Fiddleback). Though these patterns can be seen in other species of Maple, Bigleaf Maple is known for having the highest grades available.
- Janka hardness: 1,130 lb f
- Average Dried Weight: 40 lbs/ft 3
- Modulus of Elasticity: ?
5 foot diameter, 60 foot high Walnut trees are less common today in their native habitat of Oregon and California than they were 100 years ago due to the high demand for this lovely wood. Claro Walnut works easily and can be seen in everything from turned wooden bowls and carvings to rifle stocks and high-end furniture.
- Janka hardness: 1,270 lb f
- Average Dried Weight: 40 lbs/ft 3
- Modulus of Elasticity: 8.45 GPa
With grain patterns ranging from straight to wavy to highly figured and colors going from sandy brown through orange-brown to olive, Oregon Myrtle is one of the most visually interesting tonewoods available. Found along the coastline from southern Oregon to central California, Oregon Myrtle is easy to bend (a delightful characteristic, especially when building Venetian cutaways) and seemingly hypo-allergenic (having no known adverse health affects). It is a pleasure to work with and always interesting to look at.
- Janka hardness: 1,170 lb f
- Average Dried Weight: 38 lbs/ft 3
- Modulus of Elasticity: 10.37 GPa
From the big island of Hawaii comes this unusual golden-brown hardwood, sometimes seen with streaks of reddish-brown or black and having straight, wavy, figured or even flamed grain patterns. Like Oregon Myrtle, Koa is easy to work and is not known to produce any adverse health conditions. It is not unusual to see an all-Koa (back, sides and soundboard) instrument.
- Janka hardness: 2,960 lb f
- Average Dried Weight: 69 lbs/ft 3
- Modulus of Elasticity: 18.7 GPa
Stronger, denser and heavier than it’s close cousin Brazilian Rosewood, Cocobolo is a gorgeous wood, though it can be difficult to work with. Having relatively straight grain with colors ranging from yellow-orange to reddish-brown, this Central American Rosewood has a reputation for being both notoriously allergenic and cantankerous to glue. That said, it makes stunning looking guitars!
- Janka hardness: 2,440 lb f
- Average Dried Weight: 52 lbs/ft 3
- Modulus of Elasticity: 11.5 GPa
Indian (also called East Indian) Rosewood grows in India, Sri Lanka and Indonesia. Indian Rosewood can range from golden brown in color to dark brown with purple hues. Straight grained Indian Rosewood is well regarded for being very easy to work and bend, and has become the standard in acoustic guitar back and sides, though figured wood is gaining in popularity.
Tone is such a subjective thing, and opinions regarding tonewoods may be as diverse as the number of people who share them. Much like the living trees from whence they come, those opinions are subject to change. There are few (some might argue there are none) hard and fast rules regarding the incorporation of wood(s) into an acoustic guitar. Let your senses be your guide.
Additional wood species data: