My back and sides woods can be separated into several categories to avoid confusion and also to avoid reading too much into individual species that may be more similar than not. The first characteristic that affects the sound is the density of the wood. The second is the internal damping, which is a measure of how much of the energy that goes into the wood comes back out. Let’s take a look at several groupings of woods, starting with lower density species and moving up from there.
European Maple is both low density and high damping. I have frequently heard things like “a more simple sound” or “creamy” or “bright” attributed this wood. Some time ago I sat for hours with two guitars: a European maple and Brazilian rosewood, which were made by an iconic maker. They were constructed in an otherwise identical manner, differing only in the back and sides wood. It was astonishing to see that they were actually not that different. A very close listen revealed that the maple guitar emphasized the fundamental of the note slightly more than the Brazilian rosewood one, and was perhaps slightly quieter and more delicate sounding. This was in no way obvious, however. This is a very good wood and as a added bonus, it is very stable.
Low density and low damping woods include Cypress, Panama Rosewood, Red Narra and Padouk. Some of these can be medium density depending on the piece, but they tend to be light in weight. There is an unfortunate bias against these woods, generally out of ignorance, and in the case of Cypress it is more recognized as “a flamenco guitar wood” (which interestingly enough have very strong projection). I believe they sustain a little less than the heavier rosewoods but can really reach out to the back rows. If this attribute is important to you and you can live with slightly less sustain and tone color, I would seriously consider any of these woods. Panama rosewood is the densest of these and cypress is the lightest. One attribute that is often overlooked with low density back and sides woods is that the guitar ends up being a bit lighter than it would be otherwise. Lighter guitars are generally more responsive, and it has been hypothesized that strings will wear out less quickly because there is less inertia for the strings to overcome in the guitar. If you like the deep sound of many of the old Spanish guitars, these woods would also be a consideration.
Medium density and low damping woods include the well known Brazilian and Madagascan Rosewood, but also the lesser known Guatemalan Cocobolo. These woods tend to offer strong projection but also fairly interesting tone colors and prominent overtones in the finished instrument. Many people ask me–“Is Brazilian really worth it?”. Well, both of my personal instruments have Brazilian Rosewood because I get more interesting tone color sounds from ponticello to tasto compared to those that I have built with Indian Rosewood. While some sets of old growth Indian Rosewood could fit into this category, I am not pleased with the Indian Rosewood available now and so I tend to gravitate towards other woods. Good Madagascan Rosewood is indistinguishable from Brazilian in a finished instrument, and quite a bit less expensive. Guatemalan Cocobolo is harvested from the mountains of Guatemala and is very different from Mexican Cocobolo. It is also very similar to Brazilian and Madagascan and offers some unique aesthetics.
High density and low damping woods include Honduran Rosewood and Amazon Rosewood. I lack experience building with these woods and so I cannot draw direct comparisons. Many, many, comparisons have been drawn to Brazilian Rosewood (and with just about every new tonewood that comes on the market…) and on a molecular level scientists remark that Amazon Rosewood (Dalbergia Spruceana) is almost indistinguishable from Brazilian Rosewood (Dalbergia Nigra). And yet I cannot help but draw attention to the fact that on average, these woods are 20% more dense than is typical for Brazilian, so the sound cannot be the same regardless of how similar they may look or feel. I’ll add more comments when I’ve build some more guitars with these woods.
It has been said that ultra high density woods like African Blackwood have the most harmonic complexity of any of the back and sides woods. A side effect of this, however, is that they can lack the warmth that lower density woods often have. Some lesser known rosewoods in this category are Burmese Rosewood, Madagascan Kingwood, and some pieces of Mexican Cocobolo.
There are also some unique woods that don’t fit into these categories, which are Malaysian Blackwood and Ceylon Satinwood, two heavy woods that are medium to high damping. Having done a direct comparison between a Ceylon Satinwood and Brazilian Rosewood guitar, it was very apparent that while they both had a similar harmonic structure, the Satinwood was less edgy in the trebles and a little warmer sounding. I like this wood a lot because it is somewhat of a cross between maple and good rosewood.