The tone of a classical guitar

By Christopher Peppler

“The concept of tonewood is a hoax. Of the few things that we can do to a guitar and still call it a guitar, changing the wood it is made of will have the least impact upon the quality of the sound that it produces.”

Those are not my words, they were written by John Calkin in American Lutherie #69.  John built musical instruments professionally for nearly 40 years. From what I can gather, John has made mainly steel string guitars and classical guitars do have their own particular sound profiles, but his opinion should never the less be taken seriously.

Almost everything I have read elsewhere contradicts what John believes. Conventional wisdom holds that the wood chosen for the top is the ‘single overriding variable that determines the quality of tone of a finished instrument’.   Bradford Werner, a guitar player and teacher I respect, makes the following generalisations concerning Spruce versus Cedar guitar tops :

‘I find that spruce has a very direct sound with a golden bell-like sound. It is maybe a bit more clear, balanced, and sometimes has more sustain’ and ‘I find cedar guitars to be warmer, darker, and fuller sounding than spruce guitars’. Others describe the sound produced by spruce tops as pure and bold, while cedar tops produce harmonic and ringing tones’.

And of course, different guitarists and luthiers have opinions on the tonal qualities of the wood selected for back and sides. Rosewood is said to have a good bass response, maple has a clear treble response, and walnut produces a textured, earthy sound… and so on.

However, in the same article, Bradford quotes Marcus Dominelli posting on Delcamp Guitar forum that puts the matter into proper perspective. He writes;

 ‘It’s possible to generalize between spruce and cedar if you’re comparing them built in the same style, for example, fan braced cedar to fan braced spruce. But just don’t start comparing a spruce fan braced to cedar lattice, or a cedar double top!! I think it’s pretty well agreed upon that spruce tends to sound a bit crisper, with better separation and definition. Cedar tends to be warmer and darker in sound quality. But I’m continually told that in blind tests most people cannot tell them apart!! So I think we sometimes hear what we expect hear. In the end a good guitar is a good guitar, regardless of the woods used.’

So, if not just the wood, then what are the main contributors to classical guitar tone?

Obviously, the strings are the prime source of the sound that the instrument will ultimately produce. The quality and tension of the strings make a huge difference to tone; just change an old set for a quality new set to hear this. However, put that same set of new strings on a solid body guitar without amplification and the sound they make is pathetic.

A year ago, I undertook what I called my Beater Project. I bought a new $50 (RSA R700) classical guitar off the internet and then set about trying to make it sound like a $500 guitar. The idea was to modify but not remake. The top, back and sides were 3mm Basswood 3-ply; the saddle and nut were plastic, the soundboard was finished with a thick mixture of varnish and wood stain, and the strings were possibly the most inferior I had ever encountered.

I started by taking off the strings and then scrapping all the gunky varnish off the top and sanding it down. Then I applied a coat of polyurethane clear varnish and levelled all the frets. Next, I replaced the cheap plastic nut and saddle with bone, restrung with good medium tension strings and adjusted the action. A rosette I made from exotic wood veneers, a strip to decorate the bridge, and the job was done. The difference in tone? Huge! The point of this blow-by-blow account is to demonstrate the few things the average guitar owner can easily do to improve tone.

The folk at Graphtech obviously focus on the importance of strings in combination with nut and saddle. They write ‘The saddle allows appropriate frequencies to go from the string to the soundboard (to make tone) and stops others from going through easily (to make sustain). It’s the perfect mix of these two elements that create the sound we look for.’ However, they go on to point out that the soundboard has a lot to do with how the guitar sounds; ‘The soundboard’s ability and efficiency depend on its shape, thickness, mass distribution, and grain pattern – as well as the characteristics of the bridge and how the bracing on the underside is glued.’ They also acknowledge that the air in the body of the guitar is excited by the string vibrations transmitted through the top and influence both the volume and tone of the sound produced.

Now we are in the domain of guitar design and the skill of the luthier. Here are a few of the many considerations that a skilled guitar builder takes into account:

Choice of top wood – wood type and stiffness, evenness of grain, age, bracing, and finish (varnish, polyurethane, or French polish).

String scale length –  the length of string between nut and saddle has an influence on volume and tone.

Bridge and Saddle – the size of the bridge has a small influence on the tone and the nut material has a big influence.

Neck – the density of the neck wood and even the size and weight of the headstock can make a small difference to the tone.

Body – wood selection and thickness for back and sides makes a difference, as does solid wood versus laminates. In addition, the volume of air contained in the body (size of the soundbox) influences the volume and sometimes even tone. Even the inner surfaces of the body can affect sound production (shape, smoothness, glue residue).

So, in reality, it is the intricate construction and interaction of the various components that produce the tonal qualities of the instrument. Then add to that the way the guitar is played, the room in which it is played, plus the hearing imperfections of the player and audience and we have the final tone of the guitar. Oh, and then there is the matter of changing humidity, ageing wood, string fatigue and so on.

Bottom line: Good guitar makers produce guitars with good tone, sustain, and volume. Great luthiers produce guitars with exceptional sound qualities. But, I have only built one guitar from scratch and I am not even a particularly good player. However, like every classical guitar enthusiast I have encountered, I know what I like and I have a favourite guitar among several. Mine happens to be the one I made, and that probably says volumes about the subjectivity of it all.


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