The importance of wood types in lute-making

In the world of luthiery, the selection of wood types is never arbitrary. Wood, the very backbone of the instrument, shapes the resonance, timbre, and longevity of a musical instrument, whether it’s a guitar, violin, or bass. Each wood type possesses unique properties that make it more or less suitable. Let’s clarify the essential characteristics of “good” luthiery wood and dispel some unverified claims!

How Does Wood Influence an Instrument’s Sound?

What is Resonance?

A standard dictionary definition of resonance states:

resonance is the increase in duration or intensity of sounds and vibrations.

In luthiery, it’s the acoustic phenomenon that fundamentally shapes the sound and timbre of a musical instrument. Resonance is directly connected to the materials composing a musical instrument. When we mention “materials,” we refer to all the material components and their assembly, including wood, strings, pickups, shape, and size, among others.

Musical instruments are primarily crafted from wood. Each wood type has unique physical characteristics that play a role in defining the instrument’s sound. Resonance, in this context, refers to the wood’s ability to vibrate at specific frequencies. Sound isn’t created and extinguished instantly. It progresses through what we call transients, the acoustic phenomena describing the evolution of a sound from its creation to its cessation. Again, wood plays a role in the transients, the formation and dissipation of the sonic spectrum.

Wood Characteristics to Analyze

The propagation of vibrations directly relates to the material’s mechanical properties, geometry, and associated reinforcement elements. To determine wood properties that influence sound definition we examine several critical characteristics.

Density

Wood density, for a given species, is the ratio of the wood’s mass to the mass of water occupying the same volume. It impacts acoustic properties. In general, high-density materials tend to reflect more sound than they absorb. Conversely, low-density materials tend to absorb more sound. Furthermore, thicker materials tend to absorb a wider range of sound frequencies than thinner ones.

Homogeneity

In physics, homogeneity defines a material with identical properties throughout. Wood is considered homogeneous when it’s uniform and without irregularities. Here, we look at the intrinsic quality of the wood, particularly its grain, to ensure appropriate cutting. Lutheries avoid wood with knots, which impede vibration propagation and pose a risk of breakage from string tension. Identified knots disqualify a piece of wood for use in musical instrument making.

Elasticity

Elasticity represents a material’s capacity to recover its original shape after a deforming force is removed. Wood must be able to “flex” in response to string vibrations and return to its original form when the vibrations cease. We avoid materials that deform under stress and are unable to recover their original shape. The goal is ensuring the instrument’s longevity.

Role of Resonance

In luthiery, we choose woods with sufficient resonance to respond to the vibrations produced by the strings. The aim is to capture and faithfully reproduce these vibrations. Conversely, in woodworking aimed at soundproofing, we seek wood with minimal resonance. Every application dictates the material properties required.

Wood Types Used in Luthery and Their Characteristics

Maple

Maple is a commonly used wood in both classical and electric luthery. It appears in a wide variety of instruments, either for bodies, backs, or sides. It’s a dense and reliable wood. Different maple varieties feature differing visually appealing patterns. Some are even used for soundboards due to their aesthetics, like quilted or figured maple. Maple also plays a role in instruments played with a bow, recognized by its pattern on violin, viola, and cello backs. Maple is also commonly used in the construction of the instrument’s bridge.

Alder

Alder is commonly used for the bodies of electric guitars and basses, particularly by Fender. Solid bodies of Fender Stratocasters often incorporate alder. Its workability and affordability explain its common use in entry-level models.

Ash

Ash is a hard and dense wood employed extensively in the construction of solid-body electric guitars. Ash was a preferred wood for Fender Telecasters in the 1950s, later replaced by alder. Various ash trees worldwide exhibit distinct density and patterns. Ash generally has a light color, though it can sometimes display a pinkish hue. Its hardness makes it more demanding to work with compared to some other woods.

Spruce

Spruce is widely used in luthiery, especially for classical guitars and bowed string instruments like violins. It’s the standard for classical guitar soundboards. Various spruce species exist, including Engelmann (North America), Alpine (Europe), and Sitka (North America). Spruce is valued for its light weight, density, and elasticity, making it particularly well-suited for shoulder-held instruments like violins and violas.

Walnut

Walnut is prized for its density and undeniable aesthetic appeal. Visually, it boasts distinct grain patterns and a beautiful brown coloration. Several walnut varieties exist globally with slightly different physical properties. However, the presence of frequent knots often discourages its use.

Ebony

Ebony is a highly valued dark wood renowned for its extreme density. Ebony is frequently employed for fingerboards, as its density makes it highly resistant to wear and marking from instrument use. Ebony fingerboards remain stable and require minimal maintenance. Fretless guitars often incorporate an ebony neck.

Rosewood

Rosewood is an exotic wood known for its high density, making it suitable for guitar fingerboards, side panels, and bridges. Its brown hue provides an attractive appearance.

Mahogany

Mahogany is valued for its distinctive reddish hue. It is commonly used in guitar bodies and necks, for both classical and electric guitars (e.g., neck, back, and side panels). Mahogany’s long, knot-free grain streamlines vibration transfer. Many varieties exist under the collective “mahogany” identification.

Dozens more woods are employed in luthiery. It’s impossible to list them all, as wood species vary across regions and continents. Luthiers often prioritize sourcing from local suppliers when possible, resulting in the frequent use of regional species in instrument making. Examples include cypress, olive wood, and cedar.

How Much Does Wood Contribute to a Musical Instrument’s Sound?

Wood and its physical properties play a role in an instrument’s sound, but many other factors are equally essential. These include the musician’s playing style, the instrument’s electronics, the installed strings, the equipment used, the recording and listening environment, the musical register being played, and more. A change in any of these factors alters the produced sound spectrum. Individual preferences also vary widely.

Wood alone does not define a particular timbre. It dictates properties, but is not the sole determining factor in a sound. For instance, strings significantly influence a guitar’s tone. The interaction of strings vibrating with the instrument’s body yields vastly different results depending on the string set. Likewise, the instrument’s size, shape, and assembly are as crucial as the wood. Resonance chamber shape distinctly alters the final instrument timbre. Wood alone cannot fully characterize an instrument’s tone.

However, it’s undeniable that different woods yield different results, and even pieces of the same wood species exhibit unique timbres. If a luthier crafts two similar instruments with the same wood, their sounds cannot be 100% identical. Lutheries and musicians often develop preferences and distinctions by type of wood. For example, it’s often written that alder offers the best sonic balance, preserving all frequencies. Use this commentary as a guideline for wood selection, but avoid overlooking other factors that contribute to a unique sound. I’ve had the opportunity to play guitars by the same luthier and made from the same species but they still sound unique!

Despite significant research, I haven’t found precise, verifiable correlations between wood type and sound. While there are sound studies and wave propagation research online, no definitive distinctions are definitively established across different woods. Be cautious of online assertions, like maple being a perfect conductor of sound waves, promoting bright mids. More comprehensive comparative studies are necessary to substantiate these claims.

Choosing Wood Based on Instrument and Use

It’s inaccurate to state that no luthier considers wood based on need. Like any crafting project, the question arises. Whether an independent luthier creating a new instrument or a large brand launching a new guitar line, considerations are applied. Several factors come into play: wood availability, ease of access, the instrument types, and even the intended style of music or target audience.

Availability and Sourcing

The status of certain woods used in luthiery is increasingly concerning. Mass production for budget instruments encourages production of instruments with limited longevity, thereby hindering the regeneration of natural resources.

Wood sourcing is increasingly complex for musical instrument manufacturers. Some woods are rarely used because they are protected by international treaties. CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) is the international framework governing these regulations. This applies, for instance, to Brazilian rosewood used in the construction of bowed string instrument bows, a species listed as endangered since 1992. Restrictions also affect some South American and African rosewood varieties.

Wood, a primary component of musical instruments, is now carefully selected. Its quality must be exceptional, but sourcing must also be sustainable. Being a luthier often means embracing this responsibility for preserving this precious craft material: wood.

Instrument Type

Luthiers specializing in specific instrument types often gravitate towards particular woods. Bowed string instrument makers frequently use maple and spruce for violins, violas, and cellos. These types of instruments in other species are uncommon. For classical guitars, a related but somewhat more expansive scope of woods are preferred. Similarly, cypress is favored by luthiers crafting flamenco guitars due to its common growth in Spain, the guitars’ birthplace.

The selection is significantly broader for basses and electric guitars. Exploring custom shops from Gibson and Fender reveals a wide range of options: maple, alder, mahogany, ash, koa, and more.

Musical Style

Signature guitars have existed for decades! Some guitarists have a preference for bodies made of particular woods. The EVH Signature, with its basswood body, is often the topic of discussion, as basswood is a softer wood. This is not commonly appreciated for its lack of density. Yet, were Van Halen’s guitars inherently inferior in sound? No. Basswood’s limitation is primarily its reduced suitability for general-purpose budget instruments. While it’s perfectly conceivable to design an instrument with a particular musical style or artist in mind, this consideration is often secondary to other crafting elements. There is no conclusive evidence that maple is more suitable for a metal guitarist than a blues guitarist. Such notions commonly stem from personal preferences, habits, and correlative influences.

While wood plays a crucial role in determining the sound quality and instrument construction, it is merely one element in a complex sonic production process. Wood’s physical characteristics—density and homogeneity—influence resonance and timbre, but other elements, like strings, are equally significant for achieving the final sound. Environmental pressures and international regulations also complicate wood sourcing for luthiers. Selecting wood for an instrument must consider the project’s specific requirements, the resource availability, and applicable legislation.