Different types of woods affect the sound produced by guitar in major ways. This affect is all the more pronounced in acoustic guitars. In music industry, the term Tonewood is frequently used to describe wood varieties with tonal properties, that make them suitable for use as Acoustic guitar wood.
Tonewood by definition, is a wood that is great sounding and gives you a surprising bell like sound on tapping. This character is a sign of liveliness and good high frequency performance.
Tonewoods affect Sound, projection, tones, overtones, sustain, balance, dynamic range and other properties of acoustic guitars. Anatomy of these guitars comprising of their top, back, sides, neck, bracing and the woods used for these portions greatly impacts the above sound properties.
- Light but very stiff tonewoods are preferred for soundboards or tops. These surfaces transmit the string vibrations to the air.
- Hardwoods are desired for body & other framing elements.
In addition to the above, other factors which effect choice of particular wood by different manufacturers are
- Appearance like color and grain
Spruce is the most commonly used tonewood for making soundboards of acoustic string instruments. It is a very resonant softwood belonging to the pine family. It is said to have a smooth, sweet and clear sound that is a very good balance between bright and warm tones.
In earlier times, woods used to be graded by ship building industry. In majority of their tests, Spruce of some origin would be found to be lightest for a specific strength.
Common varieties and place of origins of Spruce include
It is regarded very highly by musical instrument manufacturers for its quality. It comes from Switzerland, Bavaria and Romania. It was also called as the German Spruce in the past. It has a very clear and distinguishable high overtones.
It is also known, as Silver Spruce - It is currently most commonly used wood for acoustic guitars and comes from Pacific Northwest. Sitka is a very versatile wood with broad dynamic range, clear and defined sound, suitable for both loud and soft playing. It is stronger and stiffer than other Spruces. Due to its higher density than other spruces, it is less frequently used for classical guitars.
Rocky mountains in U.S and Canada. It is believed by many to give more projection and resonant sound. It is lighter and less stiffer than Sitka, allowing the guitar top to have more vibrations This leads to more overtones and richer sound.
It originates from U.S and Canada. It is further categorized as Quebec Spruce, Appalachian white spruce, Adirondack spruce, eastern or western white spruce based on origin and shipment. Some even claim that early Martin guitars used only Adirondack spruce and Gibson relied on Appalachian white spruce before WWII.
How well will a guitar perform depends on the vibration of its top, which in turn, is determined by
- quality of the wood used
- shape and quality of the surface and the bracing.
When made of Spruce, the sound of the top improves with age and playing.
The top for any guitar will always, perform the best, if it is manufactured from a slab of wood, derived from
- radially cut pieces from quarter sawed wood, or
- center most of slab cut pieces, also called as the radial cut wood.
These pieces of spruce will have a light colour and a straight growth ring pattern. These are first choice for top, neck, back and sides of any fine guitar. However, both these are quite expensive. Perfectly quarter sawed wood is used in most expensive guitars.
For a guitar, to qualify as fine, at least the top must be quarter sawed. Some top makers use slab cut wood for sides and back to have a beautiful appearance.
The light and dark parts of the grain line represent spring and summer growth of the tree. Too much difference in shade, represents substantial differences in humidity between wet and dry seasons in the area, where tree had grown.
Guitar made of Spruce is usually quite white in color to start with. It changes to rich honey light brown color with passage of time.
Cedar and Redwood
Arguably, Cedar is the second most popular wood among the guitar manufacturers for the tops. It has been in use as tonewood for about 50 years now. Use of Western Red Cedar (WRC) has increased over the years for acoustic as well as classical guitars. Redwood, which is similar to Cedar is used more for classical guitars.
The origin of these woods is from Western North America. They have low damping (vibrates for long time when tapped) and splitting resistance than spruce. Redwood is generally denser and has more surface hardness than WRC.
Cedar has very strong grain lines and has red-pinkish and / or brown color. It has a smooth textured surface. It is more resistant to moisture, making it preferred guitar tonewood for people living in humid areas. But Cedar due to its lower surface hardness is more prone to scratches and dents.
Both these woods are comparable in across the grain stiffness to Spruce but are considerably less stiff along the grain. Treble response is largely determined by cross grain stiffness, as against bass response, which is more dependent on along the grain stiffness.
Hence, guitars made of these woods have a more brilliant (treble emphasized) tone than Spruce. The tone of guitars with these woods does not change much with time, unlike Spruce.
Cedar is commonly used for the necks of the classical guitars, particularly Flamenco guitars due to its color and light weight. Mahogany and maple are better suited for necks of steel string guitars, where the tension in the string is much higher.
Rosewood is a dense and very hard wood. Its use is preferred for back and sides of the classical guitars. Resins in the freshly cut tree gives rose flower like fragrance. Hence the name Rosewood.
It has more resonance than other hardwoods, making it an ideal choice for various musical instruments like Xylophones, Marimbas etc. It has a bright and very projective sound.
For any guitar to have good projection, the back and sides of the guitar must be good reflectors of sound. All hardwoods are good in reflecting sound, while softwoods like Mahogany are good absorbers. It has excellent acoustic and structural properties, hence
- It is possible to cut Rosewood into thin pieces, without any effect on rigidity. Such pieces are preferred for the back and sides of the guitar.
- Heat bending processes can be used on it for giving the desired shapes to the sides.
However, significant climate change can cause splitting of Rosewood along the grain. But it is very easy to repair the splitted side by simply regluing it.
Rosewood is an open-grained (porous) wood and requires treatment with some kind of filler before finishing.
Quarter sawed Rosewood with near straight grains and even color is best suited for guitars. Main sources for Rosewood were Brazil, Honduras, India and Java (known as East Indian Rosewood).
In current times, it is very difficult to get Rosewood from Brazil and India due to depletion / destruction of rain forests. Rosewood from Brazil was used by Martin till 1970, when it switched to Indian wood as Brazilian Rosewood became rare and expensive. In India also, the forest grown Rosewood is now a scarce commodity.
Due to its hardness, Rosewood is used for bridges and fingerboards along with ebony. Ebony is harder than Rosewood, but at the same time, is expensive. Hence, its use is limited to more expensive steel strung guitars.
For bridges of classical guitars, Rosewood is preferred due to its sweeter sound.
Rosewood from Honduras is also used for bridges and fingerboards. It is not a preferred wood for making guitar bodies, due to its poor bending ability. It is very difficult to bring the Honduras Rosewood to desired shape, particularly for sides of the guitar.
Below listed woods are similar to Rosewood, but inferior in structural or acoustic properties. Hence, guitar manufacturers prefer laminates of these woods over the direct use. In laminated form, these are visually quite attractive.
Mahogany is considered as the wood of choice for back, sides and neck for many guitars. It’s lower cost, durability, resonance and aesthetic, attractive finish makes it a popular choice for medium and lower priced models. Before the advent of laminates, it was also used for making the tops, for economy guitars.
Mahogany is softer and less dense wood in comparison to Rosewood and Maple. It has a warm, balanced and sweet tone with excellent lower frequencies and pronounced mid-range. The top range is quite clear but not sparkly.
The common varieties of Mahogany are
- Honduras Mahogany - this wood comes from Central and South America. It is also called American or Amazon Mahogany. It is open grained like Rosewood and hence treated with fillers before final finish.
- European Mahogany – It is suitable for furniture but not for guitars.
- Philippine Mahogany - It is sometimes used for low-cost instruments as it is very light, porous and tonally inferior.
- African Mahogany – These days, more and more guitars are made from African Mahogany which comes from Congo Basin and Western Africa. American mahogany was declared as an endangered species by CITIES (Convention on International Trade in Endangered Species) and restricted for trading. African Mahogany is available in abundance at quite cheaper prices. Its look, feel and sound are fairly comparable to American mahogany.
It is most commonly used wood for guitar necks. This is due to strength and stability; it exhibits under the stress of modern day steel strings.
It is also used for
- back bracing,
- flat place on the top,
- end blocks, and
- heel blocks
Maple is a very stiff, projective and strong wood with good tonal qualities and sustain. It is used more for back and sides of acoustic guitars. Also, Archtops used by bigbands were generally made with maple.
For acoustic guitars, it lacks the recognition of Rosewood or Mahogany. But is very commonly used for Electric instruments, violins, violas, double basses and cellos. It is a wood widely preferred for Mandolins and archtops guitar bodies. Maple is hard and very pliable which makes it suitable for this type of carving.
Small sized guitars made from maple do not bring out lower tones like Rosewood. Larger guitars, however, reinforces these tones due to their large body sizes.
Gibson, Guild and some other luthiers have built many successful maple guitars. Taylor has recently launched its 600 series, with maple sides and back.
Its high density makes it an excellent choice for bridge plates. It is sometimes used for necks, when it is cosmetically more suited. However, due to its instability, it is not used alone for necks and often laminated with cross grained Mahogany or Rosewood to increase strength.
Main types and sources of maple are
- Rock Maple from Eastern America & Canada or Hard Maple.
- Flame Maple from Europe.
- Japanese maple.
- Red and silver maple are also known as soft Maples. These are not used in solid forms but may be used as laminates.
As maple can vary a lot in hardness, the luthier has to adjust the thickness, based on the characteristics of different types. Hard Maple has brighter sound and less dampening effect than soft maple.
But, Maple in general, transmits vibrations at slow speed and has higher dampening effect than Rosewood. This leads to quick decay of notes, enhanced note separation and clarity.
Images of different tonewoods ca be seen at https://www.takamine.com/wood
We hope that the above article has given you lot of insights about the various kinds of top woods used for acoustic guitars including the classical ones. We saw that
- Preferred tonewoods for tops are Sitka Spruce, Engelmann Spruce, Adirondack, German Spruce, Western Red Cedar, Redwoods and Mahogany (middle and low end instruments).
- For back, sides and necks – Mahogany, Rosewood, Maple and Ebony are desired body woods.
We will deal with laminated woods and tonewoods for electric guitar's solid wood in our subsequent articles.