How oven-roasting wood mimics the effects of time
Bake a guitar top to give it vintage-like tone? That’s what an increasing number of acoustic guitar builders have been doing over the last decade. Whatever you call it—torrefaction, roasting, or tempering— heat is applied to tonewoods in a closely controlled oxygen-free environment that stabilizes their molecular structure and enhances their sound. The process simulates and accelerates aging of the wood at the molecular level. As a bonus, guitars emerge largely immune to the effects of humidity changes. And as a double bonus, torrefied wood takes on a golden glow, mimicking the look of older instruments.
Seasoning wood is hardly news. From rough carpenters to the finest luthiers, anyone who works with wood knows it continues to change long after it is harvested. Vintage guitars are prized for the way their tone has “opened up” over the years. This phenomenon is largely the result of wood that has physically and chemically stabilized naturally with the passage of time. Lots of time.
Guitar makers store tonewoods in climate-controlled conditions while some post-harvest changes occur. They also use kilns and air drying to help stabilize and dehumidify tonewoods before using them. But ultimately, the sweetest-sounding acoustic guitars are often those that have aged gently over decades, their innate voices blooming slowly.
The ideal guitar top is dry, stiff and lightweight—all qualities that help capture the strings’ reverberations optimally. Torrefaction (also called torrefication) goes beyond simply seasoning wood. It removes both water and volatile substances such as lignin and resins, making the wood more resistant to atmospheric changes. Its most common use is in oak flooring where expansion or contraction of planks after installation can be a big headache.
Looked at under a microscope, the grain and even molecular structure of torrefied wood resembles that of naturally aged wood. But more importantly where guitars are concerned, torrefied tonewoods sound terrific. It’s important to say that torrefaction won’t make lousy wood sound great. But it will improve any wood when skillfully applied. Dialing in the exact heat and time for a given batch of wood borders on art as much as technology.
The good news for guitar buyers is that torrefaction, once the exclusive domain of high-end guitar makers, is now showing up in more modestly priced brands. Today there are a substantial number of guitars with torrefied tops to choose from. Let’s take a look at some.
Taylor 600 Series
Taylor luthier Andy Powers has spent a lot of time (and high-grade spruce) finding the right approach to torrefaction. Those R&D efforts pay off in the Taylor 600 Series whose tops receive the process. Not only do the guitars produce gloriously aged tone, they look older. Torification gives the spruce a darker, cedar-like look—the same appearance some spruce species acquire naturally over the decades. Combined with Taylor’s painstaking craftsmanship, proven body concepts and fine onboard amplification systems, the 600 Series offers discerning players a breathtaking guitar.
The Taylor 618e Grand Orchestra has a torrefied Adirondack spruce top that helps balance the natural brightness of its maple back and sides.
Gibson has been at the forefront in thermal aging for a number of years now. The company’s Vintage lineup includes several iconic instruments that receive the treatment including the 2016 Hummingbird True Vintage model. Introduced in 1960, the Hummingbird has become known as a pivotal singer-songwriter’s instrument. Originals in good condition command big buck these days. Gibson has also experimented with various thermal treatments on carved and archtop guitars as well as maple fingerboards.
The thermally cured Sitka spruce top on the 2016 Hummingbird True Vintage imparts the kind of tone vintage instrument collectors lust after.
Takamine Thermal Tops
Built in Japan, Takamine’s collection of Thermal Top (TT) acoustic guitars is becoming another significant part of the torrefied top story. Known for their excellent value, the addition of these baked top instruments offers a played-in sound unexpected in brand-new guitars. The deep-bodied Takamine EF740S Acoustic-Electric derives its complex tone from the combination of a solid spruce thermally aged top on solid sapele back and sides. A TLD-2 Line Driver preamp and Palathetic pickup system makes sure all that harmonic complexity gets to the audience.
The extra deep orchestra body on the Takamine EF740S Acoustic-Electric develops powerful projection tonally enriched by a torrefied spruce top.
Martin Vintage Tone System (VTS)
Although the R&D team won’t go into the specifics of their process, the Vintage Tone System involves a level of precision in torrefaction that allows Martin luthiers to pinpoint era-specific tones. With access to some of the most prized vintage Martins in the company’s museum, the team microscopically compares VTS tops with the instruments on which they are based. Through a trial-and-error process, Martin has learned how to mimic the cellular structures found in some of its most revered historic guitars.
The Martin D-28 Authentic Series 1941 with VTS Acoustic Guitar features Madagascar rosewood back and sides, an Adirondack spruce top, and authentic 1941 D-28 appointments, right down to the neck barrel, heel, diamond, head taper, and slots. Martin's Vintage Tone System (VTS) is employed for the top and braces.
Recording King Torrefied Series
So far we’ve looked at guitars with prices well north of a grand. So it’s very cool that Recording King has tossed their hat in the ring with a pair of very affordable alternatives, the RD-T16 Dreadnought and the smaller-bodied 000 Adirondack Spruce. Using the same fundamental process as other builders, Radio King marries its torrefied red spruce top to a mahogany body for excellent string-to-string tonal balance.
Once you hear the Recording King Torrefied Series Dreadnought churn out chunky rhythms and warmly articulate lead lines, you may have trouble believing the its price.
Ibanez Artwood Vintage Thermo Aged Series
Calling its torrefaction process “Thermo Aged,” Ibanez offers a broad range of acoustic guitars that have received the treatment. A part of the company’s respected Artwood line, Thermo Aged tops can be found on models ranging from dreadnoughts to parlor guitars. A fine example is the AV10 Artwood Vintage Parlor Acoustic Guitar. With its aged solid Sitka spruce top it generates a big sonic punch despite the modest body size, delivering robust bass notes and trebles that sustain.
With its aged Sitka spruce top, the Ibanez AVN10 Artwood Vintage Parlor Guitar can get seriously loud and is a great value.
Yamaha LS16R L Series Concert Acoustic-Electric
According to Yamaha, its torrefaction system, dubbed Acoustic Resonance Enhancement (A.R.E.), uses techniques developed in-house to mimic the sound of guitars built decades earlier. A solid choice for fingerpickers thanks to its compact body, the Yamaha LS16R L Series Concert Acoustic-Electric has modified bracing that retains the crisp sound typical of L series instruments, but with fuller bass registers. With its solid rosewood construction and solid Engelmann spruce top that has received the A.R.E. treatment, it sounds warm and full, and delivers excellent value.
Solid tonewoods with an aged Engelmann spruce top plus revised bracing for enhanced bottom end make the Yamaha LS16R Acoustic-Electric a great choice for fingerpicking styles.
Need help choosing the torrefied-top guitar that’s right for you? Call a Musician’s Friend Gear Head at 800-449-9128 for friendly, no-pressure help in finding the one with your name on it!