Musical Instrument Tone Woods

 

The beauty and character of a musical instrument begins with the selection of ideal tone-woods.  These woods are crafted into specific shapes ideal for the requirements of the instrument.

 

The woods used in musical instrument crafting are many. However, some are most commonly used in quality string instruments, both guitars and orchestra. These are spruce, maple, rosewood, koa, mahogany, cedar, walnut, and ebony. These woods grow in various parts of the world, in different climates and under very different circumstances. Still they each have some characteristic or property which has deemed them best for a specific purpose on a musical instrument.

 

While each wood has general tonal properties, yet the tonal and resonant factor varies a bit with each piece of wood and with the amount of aging and curing before building an instrument. Tone woods also change in their tonal responsiveness with age, so as time passes and the wood ages, the tonal characteristics age too and in most cases improve with age.

 

 

WOOD AGING AND CURING: When wood is first cut, its fiber contains a great amount of moisture. The wood must therefore be dried and aged before being used in making an instrument. As the wood dries and loses its moisture content, the wood fiber shrinks and becomes lighter, thus undergoing a change of shape and density. The drying and aging process for highest quality tone woods actually requires many years. If the drying time is cut short in order to meet production demands, the instrument is very likely to have structural changes and other warp and damage problems during its life. Therefore, only fully and correctly dried, aged and seasoned woods should be used to make a very high quality, structurally stable, and tonally-resonant instrument. Only an instrument made with seasoned and aged tone-woods will maintain its correct shape, accurateness and musical trueness and performance for a very long instrument life.

 

 

SPRUCE: The top of an instrument (guitars and violins) must vibrate easily and conduct resonant wave-movement in response to sound waves emanating from vibrating strings. The top wood must also be light yet strong. Spruce is almost exclusively used for this part of a string instrument, and is almost always used on violins and acoustic guitars. The spruce tree used for better instruments must grow in climates where winter sets in quickly and in soil and weather conditions that foster slow growth. This results in even and tight grained wood patterns which respond and pulsate most favorably to musical sound waves, yet has enough strength to handle the tremendous tension of strings and bridges. A suitable spruce tree is usually several hundred years old. It must be harvested in the middle of winter when the tree sap runs out of the tree and down into the base or roots. Wood with high sap or moisture content will not result in a good, durable musical instrument with plentiful resonant and vibration (acoustic) properties.

 

MAPLE: Maple is a very hard wood and thus is used for the instrument body and neck. As a strong and dense wood, it helps to reflect and project ‘moving sound waves toward the top plate, which then  flow out through the sound holes carved in the top of the instrument, and also increases the resonance of the spruce top. Maple has a very beautiful visual appearance also.  When more exotic looking pieces of maple are used along with a very resonant spruce top, a more esteemed looking and sounding instrument results. Most musical instrument maple grows in Eastern Europe, although there are other sources throughout the world. Maple being a very dense hardwood, along with its quick projection and decay rate makes it a good performance instrument wood, as it produces less feedback causing resonance than most other tone woods. Maple provides excellent individual tone clarity and separation where every note is heard distinctly, even in chords and arpeggios, more so than with other tone woods.

 

EBONY:  Ebony has been known and valued since ancient times for its beauty, density, hardness and durability. Only the hard and dark heartwood of the tree is used, and must be cut in very specific ways and thoroughly dried before use, otherwise it shrinks and cracks, which can cause much damage after the instrument is made. Ebony is used on surface parts of string instruments (both violin and guitar)  including pegs, fingerboards, nuts, bridges, saddles, and tailpieces.

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ROSEWOOD:  Rosewood is a very popular guitar body wood, used for back and sides, and is also used for bridges and fingerboards. It has an attractive multi-tones earth color and grain appearance, but most importantly it is selected for its property to resonate a warm, rich, smooth tone with interactive overtones also added to its resonant property. Rosewood primarily comes from, Brazil and India, although some is now being used from Madagascar for guitars as well. It is a very hard wood, but its porosity gives it a warm and rich musical tonal balance. Its hardness makes it an ideal choice for bridges and fingerboards on guitars. While rosewood generally offers  a clear, bright sound with a fairly even response across all frequencies, yet it can favor mid and low ranges in general. It is known to produce clear and rich overtones making it a very popular body wood.

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MAHOGANY: Mahogany is a rigid, hard and dense tone wood that provides a distinctly wood and warm tone. It produces a balanced tone quality, especially mid-range, but not as pronounced in the lows and highs as rosewood. It is a back and sides body wood, although occasionally it may be sued as a guitar top wood also. Mahogany is generally more abundant than rosewood and therefore less expensive, but that does not mean it has less tonal qualities than rosewood, just that the two produce different tonal ranges. Denser mahogany can take on some of the sonic characteristics similar to rosewood, but generally, it’s a tone wood that will provide a pronounced and balanced tone with a noticeable midrange, whereas rosewood tends to generate stronger highs and richer lows as well.  As mahogany matures, it tends to increase in overtone resonance, and with this added to its fundamental warm mid and low tone-range, makes for a nice sounding blend of tone colors. Mahogany is also the most common choice of woods for guitar necks.

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KOA: Koa makes a very unusual and unique instrument tone wood. Primarily from Hawaii, it has beautiful appearance and grain characteristics. It has the warmth and brightness of various other tone woods combined together in one wood, thus making for an attractive guitar as well as a unique tonal color. Being from Hawaii, it is common to find it used in finer ukuleles. However, many high end guitar makers offer Koa Wood models too. When Koa is newer, it tends to be bright sounding, but as it ages, the wood mellows and adds in richness in the mid-range as well, thus it becomes sweeter sounding with time.

 

CEDAR: Although spruce is the most widely used top wood in acoustic guitars, cedar comes next and is mainly used in classical or flamenco guitars; although it has found a nitch in acoustic steel string guitars as well. It is less dense than spruce, thus providing a slightly darker and mellow tone. Cedar tends to produce slightly richer overtones, and this results in a tone with less projection but more fullness in its nature.  It tends to lose clarity when it’s played with a more powerful string attack, so tends not to be a favorite with someone who generally plays hard with a pick. On the other hand, the relative presence of the rich overtones in the sound it generates results in cedar being a favorite among finger-style players who value the quality and character of tonal colors more than volume, projection, and clarity.

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WALNUT: Much like koa, walnut is a dense wood that delivers a bright tone. It is sometimes thought to be in-between mahogany and rosewood for tonal colors. The tone of walnut will become warmer and softer with age, as is true with other tone woods as well. Walnut is a popular alternative to Koa; it is more abundant and easier to produce in guitar making, hence it is used in mid-priced guitars whereby it looks good and can offer tonal brightness, clear midrange, and an improving overall sound with age.