Nickel Thick, Dime Thin - Conflicting Information

A well made instrument is more likely to sound good, regardless of the bracing or the wood used. There really are no secrets…

Rafael Moreno, guitar maker, Granada, Spain

Here’s a link to the original article about guitar top thickness.

https://www.wilsonburnhamguitars.net/2017/01/nickel-thick-dime-thin.html

I have made over fifty classical guitars and one of the many things that I have learned about guitar making is to listen to the guitar top after I have glued on the top bracing. It’s amazing how I can change the tap tone by taken just a thin shaving of wood off the braces with a plane, or with just a swipe with a piece of 220 grit sand paper. Sanding the underside of the top just behind the bridge, the edge on the end block side, will also affect the tap tone. I have read that after the master luthier Santos Hernandez finished assembling one of his guitars, he would attach the “b” string to the guitar and tune it to concert pitch. He would then pluck the string and place his finger tips on the top to listen how this would affect the sound. As he did this around the guitar top, he would take a piece of glass paper (sand paper) and lightly sand different places on the top until he was satisfied with the sound. Take a look at R.E. Bruné’s measured plans of Segovia’s 1912 Manuel Ramirez guitar, for the most part you will see that the edges of the top tend to be thinner that the middle areas, but to me it doesn’t look like a Santos took a “systematic” approach to adjusting the top thickness.

My old guitar that had a 3mm (.117”) thick top.

Recently, I opened up my old “Hernandis” guitar, made in Japan and exported by Sherry-Brener Ltd. The label states it is a Grade No.1 and was made February 1973, it has a western red cedar top with back and sides made of East Indian rosewood veneer. It was always a good guitar, I performed on it in the final recital at the August 1980 Chris Parkening master class in Bozeman, Montana. The problem with it today is that it has a 665mm string length and there are very few people who want to play such “a big guitar”. The guitar now sports a redwood top and once I attach a new neck it will have a 650mm string length. I will write about working on this guitar in a separate post.

The original top of this “Hernandis” guitar is pretty much 2.7mm-3.0mm thick for the entire top, which is to be expected for a factory made top. The new redwood top is about 2.6mm thick in the area above the sound hole and underneath the fret board, it’s about that thick where the bridge will sit, but the edges are close to 2.0mm thick. When I tap the top of this guitar it responds with a very loud tone and some sweet overtones that tell me this retrofitted guitar will be capable of some incredible musical nuances. If you were to take my caliper and measure the top thickness from the bridge area to the edges of the top, you will see that the top thickness tapers from thick to thin. This is a very time honored technique used by Antonio de Torres, Manuel Ramirez, Ignacio Fleta and many other great Spanish makers, I am pretty confident that this was, and still is done to help create the sound these makers were looking for.

Nickel thick, dime thin.

Now, here is the conflicting information. 

In the Autumn 2023 issue of Orfeo Magazine, there is an interview with Gernot Wagner, one of the most sought after guitar makers in the world, and he states:

“…Another detail of my construction is that I don’t put any Nomex under the bridge area. I prefer to leave this area more flexible. As you know, luthiers generally make the edge of the tops thinner than the rest. In doing so, a larger part of the top is activated which means a bigger mass has to be set in motion. If the edges are made thicker, and therefore stiffer, the mass which has to be set in motion will be smaller. Less mass, more mobility.”

Hmm. That pretty much flies in the face of everything I have read and have been told by other luthiers.

Here’s what Trevor Gore and Gerard Gilet say on page 12-18 of their book, Contemporary Acoustic Guitar Design and Build, Volume 2, Build:

“Thinning the edges allows the soundboard to make greater vibratory excursions and so makes the guitar louder.”

“Thinning the edges increases the guitar’s sensitivity to added mass, i.e, the bridge.”

Take a look at what Erik Jansson wrote in the fourth edition, chapter VI, pages 6.28-6.30 of his Acoustics for Violin and Guitar Makers. The following is excerpted from those pages.

“A thinner top plate gives noticeably lower resonant frequencies but the level is little influenced. The thickness along the edge seems to be the most important (emphasis mine). The braces (fan bracing) seem rather to be a fine adjustment.”

“The thickness of the top plate seems to be the second most important (influence), especially along the edges and the width of the fastening is less important than the thickness.”

Jansson also mentions most guitar players feel that tonal strength or carrying power is the most important single quality criterion, with tone length and timbre being the second most.

So, what does all this mean to someone who wants to make their first guitar?

Don’t pay any attention to Wagner’s statement. Start off with the basic traditional work, experience making a close copy of an 1888 Antonio de Torres guitar, find the beauty of working with hand tools, experience the beauty of the wood.

What does all this mean to a classical guitarist?

Same thing, don’t pay any attention to all that information about the thickness of a guitar top. Please make a concerted effort to find that beautiful guitar that speaks/sings to you with an elegant voice, that beautiful voice that carries to the back of a performance space and draws the listener/audience member to you, the musician. Find the guitar that will create an intimate experience for you and your audience. Beauty out distances loudness, subtly stirs the heart.