|Woods & Styles...
Much has been written and spoken about the woods used in making quality Classical Guitars. Rather than waste your time and mine in an attempt to single out one superior wood for each of the parts of the guitar, I would prefer to simply state that there are many woods and indeed many variations within wood types, and each brings its own resonance characteristics to the party.
Generally it can be stated that the most importent choice of wood is reserved for the top. There are two major woods commonly used for Classical guitar tops. Spruce and Cedar, a third wood, Redwood, is not commonly used today but can produce fine guitars.
There are many varieties of Spruce utilized in the making of fine guitars. The most common found in Classical Guitars is European Spruce. Fine tops are taken from many regions within the European geography, Germany provides the standard by which all others are compared, however the comparison is rendered academic as European Spruces are the same tree grown in different climates and soils. Switzerland, Czechoslovakia and Italy are also providing fine European Spruce, Italian Spruce is very light in color and will rapidly dull edge tools do to the presence of high levels of calcium in the soil of the Dolomite Alps where it is grown.
Recently Spruce tops from within the borders of the United States have been made available. Adarondac Red Spruce from the East Coast, Engleman Spruce from the Rockies and a Blue Spruce from New Mexico are being used to produce fine guitars.
Due to the wide variety of sources there are many grain configurations available for the builder to choose. The classic top is narrow grained and evenly spaced across the top. It is however my opinion that due to architectural considerations the finest guitars are made with spruce that is narrow in the middle and wider on the outside. Within a given variety differences arise generally out of two considerations, the first being the general strength to weight ratio and the second being the age of the wood. Every aspect of quality in sound seems to be affected uniformly by these two factors.
Within the Spruce varieties, tonal qualities are fractionally different, those differences are slightly greater between the North American and European Spruces. European Spruce will produce a clearer and more focused sound with a larger tonal palette than North American Spruce. However a guitar with a very high quality European Spruce top will be a bit more difficult to play. The North American Spruce has slightly softer sound with less brilliance, but is easier to play and more player friendly.
It should be noted though that there is an element of mystery surrounding the building of fine guitars. The difference between a textbook perfect top and a top one would consider indifferent is so narrow that it could be described as a subjective rather than objective difference. The imprecise nature of our subjective senses, expressed through a complicated series of assembly steps, built on a set of subjectively generated concepts, virtually guarantees that some guitars are going to be better than others, based purely on subjective analysis. I have tops that will fit into both categories.
I would have to say that Cedar tops pound for pound produce a slightly louder guitar and are easier to play but Spruce tops produce a tighter, brighter sound that carries farther and have a greater tonal palette. While Cedar tops will produce a woodier more romantic and sweet sound. Redwood tops produce an extremely smooth and dark sound and when good are very exciting.
Back and side Choices
There is considerable controversy concerning what is the best choice for woods commonly used for back and sides. Current orthodoxy states that the finest guitars are made with sets of matched Brazilian Rosewood. I would have to conditionally agreed with that statement. However there are certain considerations that one should understand when choosing woods for a guitar.
There is an anecdotal story concerning a guitar made by the master guitar maker Antonio deTorres. The story tells us that the guitar was made with paper mache back and sides in order to demonstrate that the back and sides are not important in the sound production of guitars. The results of the experiment have never been revealed other than to say they were "interesting." I note that modern guitar builders build their finest guitars with Brazilian Rosewood back and sides.
At the same time I believe it self defeating to ignore the central message deTorres was trying to make. As stated previously the top is where the sound originates, its timbre, its useful volume, and its stroke requirements come from the top and the design considerations employed in its construction. Whereas the back and sides are not the most important, they do have a considerable effect on the sound of a guitar.
When considering what woods to build into a guitar it must be noted that the original consideration is what top wood to use, once the top has been selected the choice of support (or back and side) woods can then be made.
If a very hard, bright piece of Spruce is selected, then the support woods chosen must be of an acoustically soft nature. To match a top of that nature with a hard bright, glassy rosewood set is an invitation to a guitar that cannot be restrained from shouting some notes and cannot be made to shout others. Conversely an acoustically soft top must be mated to an acoustically bright, glassy rosewood. Both combinations will produce very fine guitars with all the characteristics found desirable in classical guitars.
Some top woods by their very nature require certain woods as support woods. The best support wood for Cedar is East Indian Rosewood. It naturally enhances the natural bright, glassy tones of the Cedar by leavening the response of the top and rendering broader the top's natural output. East Indian Rosewood makes a fine back and side wood for any top wood. It has a frequency response that does not interfere with a top's tonal output. It is for this reason that a guitar made with an East Indian Rosewood back and sides will reveal the builders choice of design and his building techniques more readily than a guitar with Brazilian Rosewood.
Redwood tops can be made with any wood and can be very nice. However I think Redwood requires a bright piece of Brazilian to be optimized.
Brazilian Rosewood is uniquely suited to the construction of Classical guitars. Its acoustical properties are generally more resonant than other woods and its beauty greatly enhances the value of a classical guitar.
Colors range from deep reds and oranges to dark chocolate browns through rich golden hues. Occasional streaks of spidery teal blue grain delight the eye and lend a striking appearance to any guitar.
There are some examples of Brazilian Rosewood that have the general appearance of East Indian Rosewood. Straight grained, dark brown in color and not particularly bright in their tap tones. One should not judge this wood as being inferior to the flashy Brazilian as this wood make the finest sounding guitars.
Care must be taken in matching Brazilian to a top as related above. The finest Spruce and the finest Brazilian don't always produce the finest guitars.
Considerations of grain orientation and width don't seem to be very important with Brazilian. Only in the difficulty of construction is there a difference. Once the guitar is finished regardless of grain, it has the characteristics of a guitar made with Brazilian Rosewood.
Brazilian Rosewood is extremely rare and for that reason very expensive, adding anywhere from $600 to $1200 to the value of the guitar.
East Indian Rosewood
East Indian Rosewood is a far more uniform wood. It ranges from a dark purple to a chocolate brown. Because of its size and plentiful numbers, fine specimens are taken resulting in straight even grained backs and sides with the grain vertical or close to vertical.
Acoustically it ranges from very bright to rather dull without the glassy richness of Brazilian. However it is the superior wood when used in the construction of Cedar and some Spruce guitars. Even in tone and response, a guitar made with East Indian can sound like a piano when properly constructed.
Due to it's plentiful supply East Indian Rosewood is not as expensive to use, regardless of its lower cost superior guitars are often made with this fine wood.