Acoustic Guitar Tone Wood Guide - Back & Sides
The wood used to form the back and sides of an acoustic guitar sound chamber does a lot more than simply look good and create an enclosure
The wood used to form the back and sides of an acoustic guitar sound chamber does a lot more than simply look good and create an enclosure. The inherent tonal properties of different woods play their part in filtering and amplifying the sound that resonates from the soundboard at the front. Through eliminating or amplifying different frequencies produced by the top, these tone woods can have a considerable effect on the overall tone generated by any given guitar. The combinations of woods therefore need to be considered carefully when they are paired up, and it is for this reason that acoustic guitars frequently feature different woods on the back and sides than they do on the top. So, what can be said about the sonic characteristics of the most commonly employed tone woods that are used for the back and sides of acoustic guitar resonating chambers?
Rosewood is without question one of the most popular and enduring tone woods known in acoustic guitar construction. It’s been used to very good effect for decades, and there are two main varieties that have been employed throughout this time. They are East Indian Rosewood, and it’s more elusive and expensive alternative, Brazilian Rosewood.
‘Brazilian’, due to its luxurious appearance and quality of tone, always used to be the most sought after variety, but relatively recent embargos on its import and export has led to the east East Indian variety becoming much more common. This shift in popularity started in the late 1950s when it was first introduced as an alternative. Although East Indian Rosewood (often referred to as EIR) is far more common, easier to produce, and therefore considerably cheaper, its presence on a guitar still identifies it as being a high-end model. If you are willing to look and spend hard enough, it is still possible to find Brazilian models, but they do come at a premium.
The Brazilian variety tends to have the more striking appearance of the two, with a dark brown complexion, often featuring chocolate orange shades, and fine black lines in the figuring. EIR is generally pretty easy to spot as being different, although the colouring is often a similar dark chocolate brown. It has a straighter more regular grain pattern than its Brazilian counterpart with less striking figuring, and it can include hints of purple, red, and even grey highlights.
‘Sparkly’ and ‘Sizzly’ are common terms for describing the sonic characteristics of the Rosewood back and sides combo. Basically speaking, it generates a strong clear presence of tone right across the frequencies. The character of the wood generates what could be described as a scoop effect on an EQ. I have heard its affect on the natural tone generated by a soundboard described as being comparable to the result a bass boost (or similar) button would generate on a Hi-Fi, where the mids are left relatively ‘flat’ and the bottom and top end are enhanced. The delayed onset and slow decay of sound generated by Rosewood results in strongly pronounced lower overtones and therefore a relatively ‘dark’ and ‘complex’ tone. Compared to the relatively ‘woody’ tone of Mahogany, Rosewood produces more of a metallic ‘zing’.
Some say that Brazilian has an incomparable tone, although others believe this is just part of the myth and legend that comes with a wood that is now so elusive and expensive. While I have heard it said that EIR lacks the projective qualities of Brazilian, some will happily argue that EIR is actually the superior variety. It all comes down to subjective taste at the end of the day, and the main things to say are that Rosewood will provide a warm, rich and responsive tone, with clear and tight bass projection that doesn’t overpower the sparkle in the midrange or trebles.
Because it produces a consistent tone, Rosewood is a good choice for players of all styles, and it’s commonly coupled with the all-rounder Spruce on the top for this reason. Because it’s been used for decades, it has a ‘classic’ tone that will appeal to fingerstylists and strummers alike.
Made popular by Martin and Gibson in the pre war era, Mahogany is a cheaper alternative to Rosewood, but don’t be fooled into believing that means that is a lesser quality. It’s just different.
With a rich dark reddish-brown colour, Mahogany is very easy to spot. It’s a stiff, hard and dense tone wood that provides a distinct ‘woody’ and ‘warm’ tone. Denser sets of Mahogany can start to take on some of the sonic characteristics of the Rosewood, but generally, it’s a tone wood that will provide a punchy and balanced tone with a relatively emphasized midrange, certainly compared to the enhanced highs and lows that Rosewood will generate. I have heard the trademark Mahogany tone described as ‘chewy’ on more than one occasion.
As Mahogany matures, its tendency to produce a focused fundamental tone will start to give way to make room for more prominent overtone content. This results in a more characterful and colourful tone, and the quality of tone generated by a Mahogany guitar will therefore change through time.
Because of it’s rich heritage and place in guitar history, Mahogany backs and sides can be heard on loads of old school recordings, and the inherent character of the tone lends itself well to blues and roots music to this day. In summary, it will provide a punchier and darker tone than Rosewood, with a prominent ‘woody’ midrange.
Sapele is an African tone wood closely related to Mahogany in both look and sound. Sapele trees are protected in such a way as to prevent over-harvesting which makes this a relatively sustainable wood that is being harvested responsibly. The deep visable grain is very reminiscent of Mahogany but Sapele tends to be a little lighter red/amber coloured and can often be striped between large dark and light patches (sometimes and inch or more thick).
Sapele has a strong low end very similar to Mahogany but where it differs is a sizzling or sparling top end that gives it more definition than it’s African sibling. That makes it a great option for multi purpose guitars or for those that want a good rich bottom end but with enough top end sparkle to give it a little shine. Still nowhere near as bright as Maple though!
Although Maple is frequently employed as the back and sides tone wood for violins, its presence in acoustic guitar construction is nothing like as prominent. There are several reasons for this, but its appearance certainly isn?t one of them. Maple tone wood can manifest itself in numerous different figuring patterns, all of which can look absolutely stunning! Many people have been charmed into spending their hard earned cash on a maple back and sides guitar almost purely on the grounds of its good looks. Curly Maple (also known as ‘Flamed Maple‘) and Quilted Maple are the two most commonly seen, although Birdseye Maple does make an appearance every now and then. It’s important to note that although the quality of the figuring in the wood can have a bearing on the price tag, it will not have any impact on the tone of the wood. That said, the density of each particular piece will to a certain extent.
Maple is a very dense hardwood, and this physical characteristic results in a relatively quick note decay. This makes it a good choice for live performance because the clarity of tone cuts through the mix well, and feedback is less likely to be problematic. It is well known for making an instrument sound ‘bright’ and loud, and generates a tight tone focused on the fundamental with very little overtone presence.
As a tone wood, Maple provides excellent separation where every note sounding at the same time has clear definition. In other words, Maple makes it possible to identify each individual note in a chord relatively clearly compared to some other varieties of wood that will provide a more blurred sonic image. ‘Transparent’ is a word commonly used to describe the inherent tone of Maple, and it will frequently provide considerably more treble and ‘sparkle’ than the Rosewood or Mahogany alternatives we have looked at already.
Rather than sonically shape the sound resonating from the soundboard on the top, Maple tends to simply amplify it. It is therefore an excellent choice for those who like a clear, loud and bright tone. Large body guitars that need some bright clarity to compensate for the boom that would other wise be generated by the size of the guitar benefit from a Maple back and sides. The Gibson J200 is an excellent example of how this works in practice. Taylor also produce the 600 series with Maple back and sides.
Koa comes from Hawaii where it has been used traditionally to build the best Ukuleles. It certainly isn’t a cheap wood to get hold of which accounts for it generally only appearing on special or limited edition guitars. Taylor are one of the few manufacturers that offer Koa on a wide range of models (infact Taylor have a whole Koa range). It’s stunning looks are one reason Koa tone woods are so sought after but it has more than a little to do with tone as well. Koa can sound very bright right out of the box and need a good amount of ‘playing in’ before the tone reaches its sweet spot. It’s worth the effort and the wait to get it there though as the brightness mellows a little to a warm rounded sparkle and rich low end. Koa will not suit pick players as it will just get too bright but finger-pickers who use the pads of their fingers or those that like to strum with their thumbs should definitely consider Koa. If you do buy a Koa guitar remember that it will seem very bright at first and will need to be played into lose that edge.
Cocobolo stands alongside Koa as a wood that really gets noticed: hailing from Mexico Cocobolo is usually resevered for special editions and custom built guitars. The bold stripes, swirls and dark lines in fiery reds and yellows certainly brings something volcanic to the equasion!
Cocobolo is a dense and stiff tropical wood and that means the tone has the same bright sparkle as Koa and Maple the other dense tone woods, however is does also have a little more low end than those two. Not as much low end as Rosewood or Mahogany but enough to balance out the crisp high end. Cocobolo makes a great guitar for those that like a crisp high end but still want the solid lows that neither Maple nor Koa can provide.