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Guitar Guru – Soft Top Woods and Durability

March 30, 2014
Guru_2014_03_Mar

Dana Bourgeois contributes the monthly Guitar Guru column to Acoustic Guitar Magazine. If you a question you’d like Dana to address in an upcoming article, please submit it to info@bourgeoisguitars.com.

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CAN A SOFT TOP WOOD LAST AS LONG AS SPRUCE?

Q: I am interested in Dana’s take on soft top woods, such as Western red cedar or redwood, both in terms of longevity and ‘opening up’ over time. Can he address this?” —CHRISTIAN MESSERSCHMIDT

A: While cedar and redwood can be as stiff or stiffer across the grain as spruces, they are almost always less stiff along the grain. Cross-grain stiffness plays a significant role in determining treble response; long-grain stiffness greatly affects bass response. It’s no surprise, then, that cedar and redwood guitars have a reputation for sparkly treble voices and boomy, less-defined bottoms.

X-braced steel-string guitars are entirely reinforced with bracing that runs diagonal to the grain, offering relatively little long-grain support. When used in conjunction with traditional X-bracing, cedar and redwood tops must be made thicker than spruce to achieve equivalent long-grain stiffness. At heavier dimensions, cedar and redwood become much too stiff across the grain, resulting in a thinner, less complex high-end response. Fortunately, cross-grain stiffness can easily be reduced by thinning at the edges of the lower bouts and/or by lightening the outermost “finger” braces.

So, what does this have to do with your question?

Perhaps because of their lighter weight, cedar and redwood tops tend to “open up,” or break in, relatively quickly. However, unless the builder pays adequate attention to longitudinal stability, cedar and redwood tops sometimes open up beyond a point that many players consider optimal, losing low-end definition as the guitar continues to be played.

In addition to tonal issues, insufficient long-grain stiffness can lead to top-bellying, which, if significant, can cause the bridge to lift. Softer fibers, especially cedar, can easily get lost in the bridge-regluing process—after several regluings, a viable glue joint may become impossible to maintain.

Well-constructed cedar and redwood guitars can have exceptionally full tonal signatures as well as the balance, responsiveness, and punch of spruce guitars. I have found that redwood, somewhat heavier and stiffer along the grain than cedar, is the better match for my building style, often exhibiting headroom approaching that of spruce. But that’s just me. Other builders, such as Lowden and Olson, make cedar guitars that put smiles on many players’ faces, and will also last as long as their spruce cousins.