Yamaha Seasons Wood to Make 'Vintage' Guitars

May 21, 2008
Chiho Matsuda, Nikkei Monozukuri
Fig 1: L36ARE and L26ARE series. The face board is made of the wood processed with A.R.E., while the rest of the materials are the same as those used in the existing L series.
Fig 1: L36ARE and L26ARE series. The face board is made of the wood processed with A.R.E., while the rest of the materials are the same as those used in the existing L series.
[Click to enlarge image]
Fig 2: Internal structure of wood: Weak portions in cellulose are reinforced, and hemicellulose is decomposed. The wood has moisture content of about 7%, which is unchanged before and after the process.
Fig 2: Internal structure of wood: Weak portions in cellulose are reinforced, and hemicellulose is decomposed. The wood has moisture content of about 7%, which is unchanged before and after the process.
[Click to enlarge image]
Fig 3: Comparison of acoustic spectrums. On the left is the spectrum of the existing L series, while the diagram on the right shows the spectrum of a guitar using the material processed with A.R.E.
Fig 3: Comparison of acoustic spectrums. On the left is the spectrum of the existing L series, while the diagram on the right shows the spectrum of a guitar using the material processed with A.R.E.
[Click to enlarge image]
Fig 4: Kazuhiko Kato, a Japanese musician, appeared at the press meeting and said that he "liked the sound" of the new model. According to Kato, the models using wood processed with A.R.E. produce both sharp and flat notes like vintage guitars and have a nice balance of overtones. They are also suitable for guitar techniques such as muting. Sitting on the right is Fumio Naruse, EAG development project leader and chief engineer of Product Development Department of Orchestral and Percussion Instrument Division at Yamaha.
Fig 4: Kazuhiko Kato, a Japanese musician, appeared at the press meeting and said that he "liked the sound" of the new model. According to Kato, the models using wood processed with A.R.E. produce both sharp and flat notes like vintage guitars and have a nice balance of overtones. They are also suitable for guitar techniques such as muting. Sitting on the right is Fumio Naruse, EAG development project leader and chief engineer of Product Development Department of Orchestral and Percussion Instrument Division at Yamaha.
[Click to enlarge image]

Yamaha Corp developed a wood reforming technology "Acoustic Resonance Enhancement" (A.R.E.), which provides wood with a tonal effect similar to changes due to aging.

Guitars made with wood processed with A.R.E. produce a "mellow sound" like a "vintage guitar" that has been played for 20-30 years, according to Yamaha. The company will release the L36ARE and L26ARE series, acoustic guitar lines using the wood processed with the technology for the face board, on June 1, 2008 (Fig. 1).

A.R.E. is a drying process to properly control temperature, humidity and pressure so that the properties of the wood are changed to those similar to a guitar played for years. The technology is applied to wood naturally or artificially dried to a moisture content of roughly 7%.

Specifically, the technology is designed to enhance the crystallinity of cellulose among three constituents of wood cell wall, ie, cellulose, lignin and hemicellulose, while hydrolyzing hemicellulose (Fig. 2). The process takes about 30 minutes.

(Lignin is a high molecular compound that deposits on the cell wall and causes lignification to harden the plant. Hemicellulose is a polysaccharide, which is insoluble in water.)

The process increases the Young's modulus and enhances the sound propagation speed. The wood processed with the technology produces the following effects when used for a guitar face board. (1) Sustain effect in the low range is improved, (2) rising level in the mid to high range is improved and (3) decay speed in the high range is enhanced (Fig. 3).

"Well settled," "mature," "warm" and "excellent resonance" were common terms used in comments made by musicians who played the new guitars, according to Yamaha (Fig. 4).

The face board used in the L36ARE and L26ARE series is made of softwood called "Engelmann SP" and is about 4.5mm thick. A.R.E. is applicable to materials other than wood and instruments other than guitar.

For example, the company is considering applying A.R.E. to violins because they use the same thin plates as guitars and many violinists wish to produce a mature sound. But it is likely to take some time before commercialization in both cases because strict conditions on temperature, humidity and pressure are required during the process.

The L36ARE and L26ARE series are priced at ¥378,000 (US$3,649, price may vary depending on country) and ¥304,500, respectively (both including tax). The prices of both series remain unchanged from the existing lineup. A.R.E. is conducted at Yamaha's Tenryu Factory (Hamamatsu, Japan), and the guitars are assembled by Yamaha Music Craft Corp.