One of my interests is how one instrument can sound so different from another. One of the big reasons I found was the type and placement of tonewoods. As I venture to make more and different speakers, I’ll be sure to try some of these more unique woods. In case you were wondering, here’s some background on some favorites:
Sitka Spruce: Sitka Spruce is used more than any other species for soundboards. It has a relatively high velocity of sound, and the highest strength to weight ratio than any other wood. Sitka’s combination of strength and elasticity translates into a broad dynamic range. It is clear, loud and tends to emphasize the fundamental of a note more than its overtones.
Engelmann Spruce: Engelmann spruce, which also grows in western North America, is a common alternative to Sitka. Because it is in lesser supply than Sitka, Engelmann often costs more. It’s a lighter and less stiff variety than Sitka, and it has stronger overtones and weaker fundamentals.
Adirondack Spruce: Adirondack, or Eastern red spruce, named after its ruddy coloring, grows in the Adirondack Mountains and in the cool forests of the Northeast. It is the king of spruces. Prior to World War II, it was the soundboard tonewood of choice for Martin and other makers. But over-harvesting of this wood led to its being all but phased out in the years after the war. For the most part, Adirondack spruce can be found on select high-end instruments. It’s a relatively heavy and stiff wood, having strong fundamentals, but a greater overtone content than Sitka, and it tends to be the loudest and liveliest of spruces as well.
Red Spruce: Red Spruce is heavier and stiffer than Sitka Spruce, and also has a relatively high velocity of sound. The wood has very distinct growth rings with light almost white summer growth and dense red winter growth. Like Sitka, it offers a strong fundamental, but it also produces a lush layer of overtones. Soundboards made out of Red Spruce have the highest volume ceiling of any species, and a unique sparkling edge to the tone that retains clarity at all dynamic levels.
Honduran Mahogany: The mid-range frequency is the sweet spot for most acoustic guitars, and Honduran Mahogany is a mid-range powerhouse. It’s also prized for volume, balance and articulation, making it one of the best all-around tonewoods there is. Honduran Mahogany yields a crisp fundamental sound, with a pleasing bloom of mid-range overtones. This makes for a very clean and direct sound, that is described as focused, dry, woody, and warm.
East Indian Rosewood: Indian rosewood has an extremely high velocity of sound and a broad dynamic range. All rosewoods have strongly pronounced low overtones which help create a complex bottom end that imparts an overall darkness of tone to the instrument. Strong mids and highs serve to reinforce overtones generated by the top, contributing to a fatness of tone in the upper registers.
African Mahogany: African Mahogany has a warm “woody” tone that accentuates the mid-range frequencies. Like all Mahogany, it’s unique internal dampening qualities create tonal balance and a crisp strong fundamental. African Mahogany is slightly stiffer and harder than Central American varieties, which expands its frequency response, and increases the production of overtones.
Makore: Makore is a lesser known tonewood that comes from the West African Rainforest. It’s a bit harder and stiffer than African Mahogany, with a corresponding boost in overall frequency response and high frequency overtones. The wood has nice tight grain, and often displays beautiful bee’s wing and fiddleback figure.
Sapele: Sapele is a highly sustainable West African tonewood that’s often confused with the West African wood Khaya. Sapele is much harder and stiffer than the Mahoganies, and it’s known for being difficult to bend. Tonally, it has many similarities to Mahogany, with crisp strong fundamentals, and a little extra treble zing.
Bigleaf Maple: Bigleaf Maple is one of the most acoustically transparent tonewoods, due to a low velocity of sound and a high degree of internal damping. Often described as having a “bright” sound, Bigleaf Maple has fewer overtones than other medium-density woods, resulting in strong fundamentals, and rapid note decay.
Black Cherry: Black Cherry has a density and reflectivity approaching that of Maple. It’s low velocity of sound produces a rich, balanced mid-range, without favoring the bass or treble frequencies. Its tone is similar to maple but less dry sounding, with more sustain and clarity in the bass and mid-range frequencies. Some describe the sound as being “buttery”. Cherry has no pores, so it finishes beautifully and develops a lovely dark, redish hue over time.
Black Walnut: Black Walnut is a little less dense than Mahogany, but is just as stiff as Indian Rosewood. Black Walnut produces excellent balance, with tonal characteristics that fall between Mahogany and Rosewood. The trebles have a unique earthy tone which records very distinctively. With its rich brown color and occasional streaks, Black Walnut has a “stripy” appearance and finishes beautifully.
White Oak: White Oak was used by instrument makers in the 20’s, and only recently has been drawing attention as an alternative to exotic tonewoods. White Oak is another wood with a low velocity of sound and a high degree of internal damping. It’s stiffer than almost all the other tonewoods, and also very dense. This gives it a “bright” sound across the tonal spectrum, with strong fundamentals, and a rapid note decay.
Cocobolo: With its spice-like scent and far-ranging coloration (with deep, black grain), this Central American relative of rosewood is known as the “piano of tonewoods,” since it produces a bright, sparkling tone that accentuates the treble. Regarded as one of the world’s finest tropical woods, cocobolo grew increasingly popular after the 1912 opening of the Panama Canal made its transport easier.