The term ‘Tonewood‘ is used to describe wood used in the construction of stringed instruments, which are selected for their acoustic properties.
In the following article we’re going to explore acoustic guitar tonewoods in-depth, and explain how wood’s characteristics such as density, hardness, and flexible strengthinfluence the tone, volume, responsiveness, and projection of an acoustic guitar.
What Makes An Acoustic Guitar Sound The Way It Does?
What really is tone?
Luthiers use very deliberate terminology to describe the sounds they hear, much like a winemaker will use terms such as ‘bouquet’ and ‘flavor intensity’ to describe the quality of the wine they produce.
As a result, the following terms are often used:
- Punchy– Powerful but controlled
- Woody – Deep, lacking metallic sounding overtones
- Airy– Spacious, not overly compressed
- Smooth – Lacking harshness, providing a balanced response
- Brittle– Loss of clarity, on the verge of distorting
- Articulate– Clear sounding with good note separation
- Boomy – A combination of bass punch with sustain
- Bright – The higher frequencies are accentuated resulting in a ‘brighter tone’
- Balanced –Does not emphasize a particular set of frequencies over another
- Crisp– A combination of articulate and bright
- Scooped – A darker tone, dominant on the lower and higher frequencies with a lack of mid-range
- Nasally/Boxy– The opposite of scooped with more dominant mid-range frequencies
- Piercing– Metallic sounding with emphasis on the higher frequencies
- Crunchy– Warm and on the verge of distorting
- Compressed– Reducing the dynamic range between louder and quiet frequencies
- Responsive – Describes the speed the sound travels.
- Warm– Lacks harshness, with an emphasis on low to mid-range frequencies
- Rich – Describes the combined sound of frequencies heard above the fundamental tone (the lowest frequency of a soundwave) and the fundamental. Different tonewoods can accentuate this, giving the guitar a ‘rich’ or ‘complex’ tone.
While it’s true that there are a lot of different factors that contribute to the sound we hear emanating from an acoustic guitar and the terminology we use to describe it, including thesize and shape of the body, and the method of construction. All things being equal, the characteristics of the woods used for the soundboard (the top), and back and sides play an enormous role.
Resonance
The soundboard’s tonewood is so influential because when a guitar is played, the vibration from the strings is transferred (via the bridge) to the top of the guitar.
How the soundboard (in combination with the back and sides) responds will shape the tonal qualities of the sound we hear (frequency response), the volume and projection, and the speed of the sound (response).
Other components including the bridge and bridge materials e.g. nut and saddle, along with the neck, and fretboard play a role in shaping the sound we hear, but it’s the soundboard that is most influential. It plays a role similar to a speaker diaphragm, projecting sound from the body of the guitar with the back and sides playing a supporting role.
On a solid wood electric guitar, the pickups tend to diminish this influence, but acoustic guitars must balance the need for a light and flexible soundboard against its ability to handle string tension and remain structurally sound.
The balance is critical.
For instance, if the soundboard is too heavy, the bass frequencies will not transfer as effectively to the soundboard resulting in a thin-sounding guitar. Alternatively, if the soundboard cannot sustain the tension created by resonance, over time it will become unstable. Resonance can be a powerful force, capable ofdestroying bridges.
The Acoustic Properties of Timber
There are many thousands of species of timber, but many are unsuitable for building guitars. To understand why some timbers are better suited than others we need to explore timber growth patterns.
Hard And Soft Woods
All trees can be classified asevergreenordeciduous.
An evergreen tree is a tree that maintains its leaves all year round. Conifers fall under this category including spruce and cedar.
Deciduous trees shed their leaves every fall and are more affected by changes in temperature and rainfall.
When a deciduous tree sheds its leaves, its growth slows and the timber becomes denser and harder, hence deciduous trees being referred to as hardwoods.
Most hardwoods are unsuitable for soundboard construction. The density of the wood requires too much energy to resonate, resulting in a dull-sounding guitar that lacks volume.
Mahogany is one exception. Being a lighter hardwood, It’s often used for soundboards, while remaining strong enough to also be used to build the neck, back and sides, sometimes all on the one guitar.
Koa, a Hawaiian hardwood (known for its wide range of colors) is less common, but also a hardwood that is used for the top of the guitar. Other hardwoods used in the construction of acoustic guitars include rosewood (back, sides and fretboard), maple (back and sides, and neck), and Ebony (fretboard).
Alternatively, many softwoods are not suitable to be used for the soundboard, because they simply wouldn’t have the strength to handle the tension from the guitar’s strings.
Some softwoods, however, are ideal for this purpose as they provide the right balance of flexible strength and lightness. Spruce is a good example and is one of the most commonly used tonewoods for acoustic guitar soundboard construction.
This is also why steel-string acoustic guitars require pickguards. Softwoods are easily marked by guitar picks.
Tonal Relationships
To understand the tonal relationship between the top, back, and sides it helps to think of the guitar’s body as a drum.
The lighter top resonates while the drum shell (the sides of the guitar body) offer stability. This all contributes to the frequency response, volume, projection, and response of the guitar.
This is why specific pairings exist e.g. Sitka spruce is often paired with Brazilian rosewood, as rosewood is known for accentuating note articulation/clarity.
How do Tonewoods Influence Acoustic Guitar Tone?
It helps to look at the wood a guitar is made from like an engineer might assess an equalizer.
The tonewood’s characteristics define the frequency response of the guitar. Mahogany for instance has an excellent midrange response. Spruce, on the other hand, being light and very flexible, offers a wide dynamic range due.
The table below demonstrates how some of the different characteristics of wood manifest themselves concerning tone.
| Property | Impact On Sound |
|---|---|
| Density | The density of timber affects how the energy from the strings is absorbed. ‘Dense timbers provide less absorption, especially anywhere above the mid-range, resulting in a stronger influence from the wood itself. Softer (less dense) timbers tend to absorb more of the vibration resulting in a warmer more evenly balanced mid-range with quick decay Mahogany is a good example. |
| Hardness | While there is a correlation between the two, density and hardness refer to different things. Density describes the volume of the material whereas hardness defines the literal hardness of the wood and accentuates higher frequencies. |
| Flexible Strength | Stronger more flexible timber receives more energy from the strings producing a wider dynamic range with great clarity, volume, and projection. Spruce is the obvious example, and this is why it’s a popular tonewood. |
Humidity
High moisture content dampens the sound of an acoustic guitar. As the wood expands due to higher moisture levels, the energy from the guitar’s strings is more difficult to transfer, resulting in a duller-sounding instrument, often described as lifeless.
Due to the physical changes wood undertakes under different relative humidity levels, and the way the soundboard of an acoustic guitar is constrained by the sides of the body, the high moisture content may also result in structural problems.
These changes can result in tuning instability, intonation issues, and risk of permanent damage e.g. cracking and splitting. This is why in certain climates humidity control is important.
What about Laminated Woods?
Laminated timbers tend to be less efficient at transferring the vibrations from the strings to the top of the guitar, at least in most cases. But they are cheaper and easier to work with as they allow the luthier to use a select grain pattern for the top, utilizing less expensive grades for the lower sheets. Generally speaking the more expensive the guitar the more likely it is to be built from solid timber. (more on laminate guitars toward the end of this article).
The Components of the Guitar
How the Back and Sides Affect the Sound of a Guitar
The back and sides of an acoustic guitar play an important role in terms of stability.Flexible strength is less important, although the hardness of the timber will determine how easily the guitar is marked or dented, which tends to occur more often to the back of the guitar.
In most cases, the back and sides will utilize the same timbers.
The Neck
Timbers used for the neck are chosen for strength and density. The neck of a guitar must support the tension from the strings while ideally being light and easy to carve. Mahogany and Maple are the most common woods used, with maple seen more often on the electric guitar.
Fretboard/Fingerboard
The fingerboard orfretboardwill ideally look attractive yet be hard enough to stand up to the abrasiveness of the steel strings while also providing a smooth playable surface. Rosewoods have long been the most utilized fretboard material due to their innate hardness and oily nature, reducing tension between the fingers and the neck.
Ebony, a less common and more expensive hardwood, shares many of the same qualities of rosewood and contrasts nicely against natural timber surfaces due to its darker appearance.
Bridge
The wood used for the bridge is important, it directly transfers the energy from the strings to the soundboard. It also must be durable enough to withstand the pressure and tension created by the strings. Generally, hard, dense timbers transfer energy more effectively while also being highly durable.
What Is Quarter Sawing?
You may have come across the term ‘quarter sawn‘ which refers to how the timber is initially cut or ‘ripped’. The most common and least expensive option is plain sawing. This means the length is continually cut along the same axis.
Quarter sawing refers to the process of first cutting the length into quarters (think of an X intersecting the rounded grain pattern) and then being cut lengthways.
As seen in the diagram above, the end grain pattern is defined in this way. A plain sawn section of timber is also more likely to split, while quarter-sawn timber is stronger, more visually appealing, and less likely to be compromised when affected by tension.
The Most Commonly Used Tonewoods for Acoustic Guitar Construction
In the following section, we’ll take a look at the most commonly used tonewoods and describe them in more detail along with the components of the guitar they are best suited to.
Spruce
Acoustic characteristics
Easily the most commonly usedtop wood for acoustic guitars and classical guitars. When compared to Cedar (another commonly used soundboard timber), spruce is lighter and possesses greater flexible strength resulting in a wider dynamic range and bright, responsive tone.
The main appeal of Spruce aside from its availability is its compatibility with many styles of guitar. Not to mention its ability to age gracefully and look andsound better over time.
The four most common species of Spruce used for acoustic guitar soundboard construction areSitka Spruce,Engelmann Spruce (European Spruce), and Adirondack Spruce, and German Spruce. Sitka Spruce is best known for its balanced tone, whilst Engelman is typically a lighter, more supple tonewood resulting in less projection (velocity of sound). Adirondack Spruce produces a wider dynamic range than Sitka and is considered more responsive.
Spruce projects extremely well and has a perceived loudness and bolder sound when compared to Mahogany. There’s more presence and complex overtones in the top end with less emphasis on the bass. People often describe it as having a snappier, more aggressive response.
Spruce tops are often paired with a darker wood for the back and sides such as rosewood or mahogany to help even things out and bring balance to the overall tone.
Appearance
Spruce is light in color, often described as blonde, or amber, and features a tight grain pattern. Spruce tends to take on more of a darker, golden appearance as it ages, providing visual character to older instruments.
Cedar
| Component | Soundboard |
|---|---|
| Density kg/m3 Dried Weight | 370 |
| Hardness Resistance of wood to dents and wear. Measured as the amount of force required to embed a .444ml steel ball halfway into a sample of timber. | 1560 |
| Tensile Strength Bending strength before rupturing e.g. breaking | 51.7 |
| Flexible Strength The amount of stress required to deform the timber | 7.66 |
Acoustic Characteristics
Cedar (a member of the Mahogany family, sometimes referred to as Indian Mahogany) is a softer wood than spruce and as a result produces a warm tone, darker, and more complex sounding in comparison.
Cedar is also considered strong yet light, but not to the same degree as Spruce, especially along the end grains where it can be brittle. As a result, it is unable to drive the same amount of volume as the stronger more flexible Spruce and decays faster.
This is the most likely reason you will notice many vintageacoustic guitars are madefrom Spruce as they tend to remain playable for much longer.
Appearance
Cedar is finely textured and tends to feature a more linear grain pattern. Colors can range from pale yellow/cream to dark with honey tones.
Mahogany
| Component | Soundboard, Back, and Sides |
|---|---|
| Density kg/m3 Dried Weight | 590 |
| Hardness Resistance of wood to dents and wear. Measured as the amount of force required to embed a .444ml steel ball halfway into a sample of timber. | 4020 |
| Tensile Strength Bending strength before rupturing e.g. breaking | 80.8 |
| Flexible Strength The amount of stress required to deform the timber | 10.06 |
Acoustic characteristics
Mahogany is defined as hardwood but is perhaps better identified as a ‘soft’ hardwood. More commonly seen as a back and side pairing for acoustic guitars.
The sound of Mahogany is very much in line with how it looks visually. That is to say dark, dense, and warm.
A common tonewood, all-mahogany acoustic guitars (back, sides, neck, and soundboard) are known for offering clarity and balance, accentuating the mid-range, and offering up a mellow,warm tone.
Most commonly used as a top wood with Brazilian rosewood back and sides its density helps to roll off a bit of that top end to create a smoother sound with less trebly, complex overtones. It also does a great job of promoting the bass frequencies which you can think of as creating a ‘rich’ or ‘thick’ sound, or strong fundamental.
It has a very pleasant warm tone that many describe as ‘woody’ or ‘earthy’ because of its full-bodied sound and quite subtle overtones.
Because of this prominent emphasis on the bass and mid-range with a less harsh top end, it can really make things like single notes or fingerpicking sound balanced and full.
Because of that top-end roll-off, it also has a bit less projection when compared to spruce. But that is not to say it’s quiet by any means, from a raw decibel output that additional bass makes it more than capable of holding its own in a live setting.
Appearance
Tightly grained with a uniform appearance and less discernible grain patterns it’s an attractive ‘chocolate brown’ timber that tends to look better as it ages.
Species
Honduran mahogany (genuine mahogany, big-leaf mahogany, Brazilian mahogany, American mahogany) is highly regarded and considered superior to “true” mahogany species. While there are several species of mahogany, Honduran mahogany became better known as genuine mahogany due to lesser-known species of mahogany being sold under the name “Honduran Mahogany”.
While less abundant today, it is still available, however, “True Mahogany” species such as African Mahogany (Khaya) and Sapele are commonly used tonewoods.
Rosewood
| Component | Back and Sides, Fingerboard |
| Density kg/m3 Dried Weight | Brazillian Rosewood – 830 Indian Rosewood – 835 |
| Hardness Resistance of wood to dents and wear. Measured as the amount of force required to embed a .444ml steel ball halfway into a sample of timber. | Brazillian Rosewood – 10870 Indian Rosewood – 12410 |
| Tensile Strength Bending strength before rupturing e.g. breaking | Brazillian Rosewood – 114.4 Indian Rosewood – 135 |
| Flexible Strength The amount of stress required to deform the timber | Brazillian Rosewood – 11.5 Indian Rosewood – 13.93 |
Acoustic characteristics
Rosewood (back and sides) are often paired with spruce, providing a balanced yet complex tone, and rich sound. Rosewood provides good articulation, especially on the lower-end frequencies. It’s less dominant in the mids, but when paired with spruce produces a balanced and wide dynamic range.
Appearance
Rosewood is a very dark (chocolate) tonewood and contrasts nicely with a lighter timber top. Rosewood is a hardwood but is also moderately porous. It’s also a very consistent wood and doesn’t tend to vary much between trees.
Maple
| Component | Back and Sides, Neck, Fingerboard |
| Density kg/m3 Dried Weight | 705 |
| Hardness Resistance of wood to dents and wear. Measured as the amount of force required to embed a .444ml steel ball halfway into a sample of timber. | 6450 |
| Tensile Strength Bending strength before rupturing e.g. breaking | 109 |
| Flexible Strength The amount of stress required to deform the timber | 12.62 |
Acoustic Characteristics
Maple is a hard timber and accentuates the mid and upper ranges. It is a common neck and fretboard timber used in the construction of electric guitars but rarely seen on the acoustic guitar, most likely due to its density and weight.
It is a common back and sides material and due to its density is highly responsive with good compression and sustain.
Many people make the point that maple influences tone much less than other species, lacking the character of spruce and mahogany.
Appearance
Another pale timber, maple has a more whiteish appearance than spruce and often features highly decorative grain patterns. Maple is often seen as a book-matched veneer on electric guitars. The highly decorative grain patterns of flamed maple, quilted maple, and spalted maple can look stunning when finished with a high gloss sealer.
What is book matching?
Book matching is the process of mirroring the grain patterns of two sections of timber, for either the top or back of the guitar body. This is done by using a solid piece of wood half as wide as the guitar’s soundboard. The timber is then cut in half along the edge of the timber reducing the depth by half, resulting in two sections of timber with matching grain patterns. The two halves are essentially opened like a book and joined by the edges in the center to create a book-matched section of timber.
Walnut
| Component | Soundboard, Back, and Sides |
| Density kg/m3 Dried Weight | 610 |
| Hardness Resistance of wood to dents and wear. Measured as the amount of force required to embed a .444ml steel ball halfway into a sample of timber. | 4490 |
| Tensile Strength Bending strength before rupturing e.g. breaking | 100.7 |
| Flexible Strength The amount of stress required to deform the timber | 11.59 |
Acoustic characteristics
A medium-density tonewood. Walnut produces a warm, airy, woody tone similar to African mahogany with fewer overtones and more of a focus on the prominent mid-tones. It has a very even dynamic range, meaning it doesn’t accentuate one frequency band over another, resulting in a very balanced sound.
Appearance
A dark (light brown to chocolate) tonewood with hints of red and purple. It is highly decorative and features a tight grain pattern.
Koa
| Component | Soundboard, Back, and Sides |
| Density kg/m3 Dried Weight | 610 |
| Hardness Resistance of wood to dents and wear. Measured as the amount of force required to embed a .444ml steel ball halfway into a sample of timber. | 4490 |
| Tensile Strength Bending strength before rupturing e.g. breaking | 87 |
| Flexible Strength The amount of stress required to deform the timber | 10.37 |
Acoustic characteristics
Koa is a hard, dense tonewood that accentuates with mid and upper ranges, providing good articulation and crispness in the upper ranges. It holds its tone nicely when strummed with a good response.
Appearance
Dark brown with streaks of blonde. Koa is a highly figured tonewood that looks beautiful as a soundboard. Taylor’s range of Koa top guitars in particular is very appealing.
Cocobolo
| Component | Soundboard, Back, and Sides |
| Density kg/m3 Dried Weight | 1095 |
| Hardness Resistance of wood to dents and wear. Measured as the amount of force required to embed a .444ml steel ball halfway into a sample of timber. | 14140 |
| Tensile Strength Bending strength before rupturing e.g. breaking | 158 |
| Flexible Strength The amount of stress required to deform the timber | 18.7 |
- Information sourced from the wood database
Acoustic characteristics
A dense, strong tonewood. Cocobolo’s density results in a bright-sounding guitar with great sustain and immediate response when played.
Appearance
Displaying a wide range of colors from reds to purples and yellows. Cocobolo often changes colors after being cut and can be polished to a beautiful glass-like finish.
A Tonewood Comparison – Mahogany V Spruce
Now, that we’ve discussed the characteristics of the most commonly used tonewoods in acoustic guitar construction it can be useful to compare two tonewoods directly, to really see how the choice of timber affects the sound of an acoustic guitar.
In the following section, I am comparing Mahogany to Spruce as a soundboard material. With our newfound knowledge of the fundamental tonal qualities of each wood, we can get a better idea of which characteristics might benefit a particular style of playing.
Mahogany:
One of the stylesmahogany really helps to accent is fingerpicking, because we are primarily using single notes we want them to sound as rich and thick as possible. In particular, when picking bass notes with your thumb the extra low-end really helps widen and project the sound.
Whereas abrighter sounding woodthat doesn’t have that pronounced mid-range and bass response may make the single-note playstyle of fingerpicking sound a little thin and reedy sounding.
But it’s also worth mentioning that because of the perceived quieter volume due to the less prominent top-end when compared to spruce. It can make competing with a singer, or god forbid a drummer, challenging if you play unplugged. You might need to consider apickup system, or some kind of amplification to make yourself known on the stage.
This makes mahogany a less common choice for strummers who are less concerned with the bass response and just need as much cut and projection as possible.
Being a more dense wood it’s also heavier than spruce, but this shouldn’t be something that concerns you as acoustic guitars are seldom heavy enough to cause problems. It’s something that becomes much more noticeable when you use a solid mahogany electric guitar.
Popular models of guitar that use Mahogany:
- Martin D15m
- Taylor 520
- SeagullS6 mahogany
Spruce:
Spruce has a much more direct tonality. This makes it ideal for things like worship guitar or just general band situations where you need those high frequencies to be able to slice through the mix.
However, for some people, the lack of emphasis on the bass and mids can make ‘solo’ playing, particularly fingerpicking, sound a little abrasive and feel like it needs a bit more of the body that mahogany offers.
But that doesn’t make the wood inappropriate for these styles, it’s incredibly common to pair a spruce top with a darker/richer sounding back and sides to help bring balance.
This way you get a little bit of everything, the cut, bite, and volume of the spruce top while the darker back and side woods will still help give you that girth and body you need when you need to play something like a fingerpicked piece.
It’s important to always judge a spruce-topped guitar by taking into account the woods it’s been paired with to get a better idea of the instrument’s overall tonal picture.
Popular models of guitar that use Spruce:
- Taylor Engelmann Spruce
- Martin custom shop
- Takamine 30 series
Other Factors To Consider
While it’s all well and good picking a tonewood, or set of woods, that on paper match your preferences. It’s important to remember that there are many other factors that play a role in determining your final tone.
These factors can be so impactful that they will actually offset the tonal qualities of the wood, so it’s very important to take these into consideration.
The Size Of The Guitar
While we may talk about spruce being louder or mahogany having a more pronounced bass.
The size of the guitaralso will influence these same elements. You can read more about body sizes, and style and how this affects the sound of an acoustic guitar here.
Laminated Tops
Laminating the top of a guitar is a process in which instead of using a single piece of wood (which we call a solid top) they instead use multiple, thinner pieces and seal them together using a mixture of heat, pressure, and glue.
This is a cheaper process and saves the manufacturer on some wood costs. Plus, it’s also a little bit more durable, being less susceptible to things such as climate and humidity changes.
Generally speaking, laminate guitars lack a little bit of that sustain and rich resonance a solid top provides. As solid wood guitars age, their resonance and projection can actually improve, whereas laminated tops tend to stay pretty stable.
Electronics And Mixing
It’s common these days to install pickup systems in your guitar, or perhaps they already come from the factory with a pre-amp installed.
If playing plugged in, you have a tremendous amount of control over the frequency balance of your instrument with EQ or adjusting the particular voicing of the pickup you use.
This can really enable you to dial in the tone of your guitar to your preferences, when amplified, allowing you to place a far bigger emphasis on factors such as how much you like the look and feel of a particular kind of wood.
Summary
Hopefully, after reading the information above article you have a better understanding of what tonewoods are and how they influence the sound of an acoustic guitar. I’ve always considered tonewoods filters, emphasizing specific overtones while reducing others, coloring and shaping the overall sound of the guitar, and controlling volume and response.
Keep in mind, as time passes and more traditional tonewoods become scarce, (and more expensive) the tonewoods used to make acoustic guitars are likely to slowly change over time. Sustainability is already playing a role concerning the availability of many traditional tonewoods and as more guitars are built this is only likely to increase.
If you enjoyed this article, be sure to check out some of our other articles on acoustic guitar design and construction.
