Why Acoustic Guitars Sound Better With Age

I’ve long been fascinated with vintage acoustic guitars and after 25 years of playing, I still get goosebumps when I’m in the presence of a six-string that is nearly half a century my senior. But other than the extreme price fluctuation between a 2019 Gibson J-45 and the 1942 model that it replicates, is there really any difference in the sound quality? They are both made of the made of the same stuff and crafted by luthiers using the same time-honored techniques, but the old-timers I know have always believed the older one just sounds better.

Do acoustic guitars really sound better with age?

Yes, they do. Quality-made guitars that are properly maintained sound better with age, and the main reason is relatively simple: They are carefully made of purposefully chosen wood.

•        Over time, the wood experiences changes at the cellular level which generally stabilize the guitar and makes it less susceptible to atmospheric fluctuation.

•        This “equilibrium” results in an improvement of what’s known as the “frequency response” of the instrument, which usually results in a more pleasing sound.

Before I get into why an acoustic guitar will get better with the passage of time, let me first get something out of the way. Key words used above include “quality” and “maintained”. That $30 guitar you bought on Amazon or the guitar you found in your flooded grandfather’s basement does not fit into this conversation. Also, it can be entirely subjective whether or not a guitar will sound better over time.

Acoustic Guitar + Time = Better Sound?

A guitar is alive! Sure, it can’t get around on its own, feed itself, nor does it have the capacity for rational thought or reason. It does, however, react to its environs. The various woods of the top, back, and sides, the bridge, the internal bracings, fretboard, and neck all respond to changes in humidity, temperature, air pressure, and human oils.

There is little doubt both in the luthier community and in circles of musicians that guitars get better with age as a natural consequence of the aging of wood, and the way these woods are combined to make a quality acoustic guitar. But is there any evidence beyond the anecdotal?

Alan Carruth, a guitar builder out of New Hampshire, has done much research on this subject and has pointed out a big factor of tonal change. Wood is comprised of cellulose, lignin, and hemicellulose among other things. To quickly summarize, cellulose is the main constituent of the cell walls found in plants. Lignin a polymer in the cell walls which gives them strength making them more rigid. Hemicellulose is an element that is found with cellulose in most plant cell walls which is amorphous and not very strong.

Over time, hemicellulose evaporates from the wood affecting various characteristics of the guitar, namely the loss of weight which tends to make a guitar more resonant. The result is typically an improvement in the sound quality. You may have heard someone speak of a guitar “opening up” after the passing of time. This improvement in resonance and increase in low-end frequencies is usually what is being referred to.

As the guitar goes through this process, it becomes more resistant to environmental factors such as changes in humidity and temperature, which in turn makes for a more stable structure and a more consistent sound regardless of its environment.

One must note that a good deal of aging has already taken place prior to pieces of wood coming together as a guitar. Too many changes take place in wood after being harvested to immediately take a chunk from a freshly felled tree and turn it into a guitar. Like the tobacco used in a cigar, the wood has to be properly stored and aged for a time before landing on the workbench. However, that wood will continue to experience changes over its life after being shipped, cut, heated, shaped, glued, and held under string tension.

The species and quality of wood also factor into the quality of the tonal equilibrium reached by a seasoned guitar, which is why this author disqualifies the so-called “guitar” you found in the clearance section of your local Wal-Mart. Nicer, more expensive woods like Honduran Mahogany or Rosewood from Madagascar may produce a higher quality sound as they age, but the same principles apply to more affordable woods such as Spruce or Maple.

Whether it be a $2,000 Taylor or a $200 Fender, each guitar will evolve with a few years under their belts. The important aspects of the guitar’s tonewoods has less to do with its rarity or exoticism than their natural properties working in harmony with one another. According to guitar maker Rick Turner, “The stiffness, resonant properties, density, and ultimate strength are the four most important aspects of what defines a tonewood, and these are also the properties that change with age and thus affect tone and responsiveness of guitars.”

Turner goes on to explain that luthiers build guitars with the idea in mind that a guitar will sound much different 24, 48, 72 hours after construction is complete. It will even sound a little different in three months. While this evolution slows down in the guitar’s life, it continues on for much longer as the guitar is put to work.

Do acoustic guitars sound better the more they are played?

The natural aging of wood isn’t the only factor that enthusiasts swear by. The number of hours logged is also thought to have an effect. It may sound disgusting, but human oils can play a part in the aging process of a guitar. As a guitar is subjected to the hands of a performing musician night after night, show after show, the areas of exposed wood on the neck and fretboard in particular will absorb the inevitable discharges of dead skin, sweat, spittle, and even the occasional tear.

While corrosive to guitar strings and other metal parts of a guitar, this can act as a sort of sealant for the wood thereby keeping unwanted moisture and dirt out of the wood grain. I will say that excessive crud on a fretboard can affect the intonation and too much dirt getting underneath a guitar’s finish can have negative consequences, so a good wipe-down is in order from time to time. However, the natural absorption of sweat and subsequent evaporation after a few years on the road can be a good thing.

The effect string vibration has on guitars has also been thought to alter its tone over time, mellowing out the guitar as it ages. There have even been attempts to artificially age a guitar by way of simulating the effect of a guitar being strummed for hundreds of hours. I must confess that I do not believe this to be a factor in the aging process of the guitar. In fact, a study (PDF) was done to determine whether or not vibration treatment actually changes the tonal quality of a guitar.

Player evaluations revealed no discernible differences in tone. However, there were “subtle, but significant” differences noted in the measurements of frequency response before and after the treatment. However, the study was not able to determine whether or not those changes were due to the passage of the three months it took to conduct the study, the season change from summer to autumn, or the amount of playing time received.

Something else worth considering is the fact that a scientific or academic experiment does not have the capacity to answer is whether or not any tonal changes in a guitar make for a subjectively better-sounding instrument. That is just something a musician has to answer for themselves.

Another factor in the aging tone of a guitar:

As a career guitar player, I will admit that much of the “breaking in” of a guitar has to do with the feel of the guitar, not just the tonal qualities of the materials from which its made. However, it is my belief that the better a guitar feels to a player, the better it will to sound. A player becomes more comfortable and confident with a particular guitar.

At the risk of sounding too esoteric, I would posit that the the tone of a guitar has as much (maybe more) to do with the way it is being played. A guitar’s sound is not only determined by the physical properties of the instrument, but by the approach taken by the one who wields it. The intensity of the strum, the tightness of the grip on the strings, finger picking versus flat picking, the maturation of the player’s techniques – these are incredibly significant factors of guitar tone that cannot be overlooked.

My guitar is 25 years old. Why did it not improve over the years?

There are a number of reasons as to why that 1939 Martin D-45 in the bulletproof display case might sound better than my less expensive, late model replica. Granted, there are some factors that simply don’t have to do with the mere passage of time. A particular species of wood that was used in ’39 may now be federally protected or otherwise unavailable. There also may be differences in quality control at the factory.

There are other ornamental additives (inlays, bindings, nut & saddle material) on guitars that can affect their overall sound. An old guitar may have a nut made of bone, but in newer models they cut costs and switched to plastic. I’ve even had colleagues that stopped buying a particular brand of guitar because the main factory moved to a region of the country with a vastly different climate.

There are even bigger reasons why a 1960 Gibson concert size sounds vastly more amazing than your 1994 Rogue. At that point, you are comparing apples and regurgitated oranges. You can’t put a lemon of a guitar into a climate controlled cellar for a quarter century and expect it to come out sounding like it was crafted by ancient mystic beings whose hands had never touched anything “unclean”. But a well-made and well-loved guitar, even if it’s inexpensive, is going to age very well and bring you many years of audible pleasure.

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