As a traditional instrument of Hawaii, ukeleles are often constructed from Koa.
Koa and mahogany are two types of hardwoods commonly used in the construction of guitars and Ukeleles. Mahogany is the more common of the two, and as a result, is significantly cheaper. Koa is native to Hawaii, and comes from a variant of the Acacia tree. There is some debate about the relative merits of the two different woods, particularly in acoustic instruments.
Sound
The sound of Koa is quite distinctive. It is noted for its sparkling high overtones, but is said to lack weight in the bass range. As a result, it is a popular choice for small acoustics and high-end ukuleles, as they do not need a low end. Mahogany is a warmer sounding wood that has the opposite characteristics; it sounds full and rounded, but may lack some high-end. As a result, it is more commonly used on electric guitars.
Appearance
One of the most immediately striking things about Koa is its appearance. It has a dramatic tiger-striped grain with high contrast highlights. Because of this, it is often used for highly figured "flamed" tops, as makers want to make the most of its dramatic appearance. Mahogany is a more consistent wood, with a dark finish and a darker, less uniform grain. It is commonly used for guitars with painted bodies, or the backs and sides of acoustics.
Price & Exclusivity
Because Koa only grows in Hawaii, it is understandably in short supply due to the small area of the islands. Mahogany is one of the more plentiful woods in the world, and it grows in a variety of locales, making it more readily accessible. As a result, the price of Koa reflects its exclusivity, and it is generally used on pricier limited edition instruments.
Environmental Concerns
As Koa only grows on the islands of Hawaii, its population needs to be carefully controlled; this is not just to prevent extinction, but because the living trees on the island are a pivotal part of the delicate ecosystem. The trees support a number of endangered species during their lifetime. Due to this, the Koa trees themselves are on the endangered species register.
Tags: commonly used, Mahogany more, endangered species, only grows