So back to the world of Acoustic Guitars… this wonderfully confusing world can be more than complicated. Previously we have talked about tone wood on Acoustic Guitars and the sound difference that this makes. Now we take a look top wood and the difference that this makes on sound. So the big question that everyone should know is: what does the top of an acoustic guitar really do?
The best way to think about the top on a acoustic guitar is to think of a billows. When a acoustic guitar is strung and tuned to pitch there is roughly 180-200lb’s of Tension on the guitar. When you strum the guitar the sound waves, generated by the strings, are transferred into the top causing it to move in and out. This flexing acts as a billows and push the sound waves throughout the guitar body and out the sound hole generating the tone that we hear. Because of this function the most sought after quality in Acoustic Guitar tops is elasticity/strength/weight ratio.
Spruce – The Age Old Stand By.
By-and-large Spruce of some variant is the most common top wood. Walk in to any acoustic guitar room anywhere in the country and you will see that at least 80% of the guitars hanging on the walls have some sort of spruce top. The reason for this is that Spruce has a very high strength/weight ratio and it also has a significant amount of elasticity to it. The Function of a guitar top requires a large amount of strength and elasticity and thus spruce has always been a popular option.
Types of Spruce
There are a number of different types of spruce you will find on acoustic guitars. The most common type is Sitka Spruce. Sitka spruce, from the area in Alaska with the same name, is an incredibly popular and a affordable topwood. There is currently an incredibly large supply of this wood and it can be purchased at very reasonable prices so it is the most commonly used wood. Sitka spruce started to be used as a substitute to the more popular Adirondack Spruce during the late 21st century after Adirondack spruce became increasingly rare from over use. Adirondack
spruce is commonly seen on pre-war guitars and is still used today on many high dollar Acoustic’s. The grain patterns and property’s of Adirondack Spruce give it a even higher Elasticity/Strength/Weight Ratio. This is partially due to the wider grain pattern that is common in Adirondack Spruce.
Spruce’s composite consists of dark “hardwood” and lighter “softwood”. The lighter lines in spruce are a very flexible light material with the consistency roughly equal to that of Styrofoam. By having wider grain Adirondack spruce has more flexibility and elasticity to it making it a more responsive and brighter wood than Sitka spruce. Generally speaking spruce is known for its durability and its clarity. It does not compress or distort when played aggressively and can act as a great sound board wood.
Ceder – The Finger Picking wood
Ceder is on of the most popular alternatives to spruce. It is softer, not as strong or as elastic as spruce. It is, however, more stable with changes in moisture content. Colors range from light brown through reddish browns to chocolate brown. It has a powerful fingerstyle tone with much brilliance and sustain, wonderful clarity, and focused bass, with a dry sound. Cedar does have a tendency to compress if you play it aggressively with a flat pick. Cedar is very common on classical guitars but is seen on steal string guitars.
Mahogany and Koa – The Other Options
When working with warm tone woods it is not uncommon to see guitars built with the same top as the back and sides. This is because the warmer, more elastic woods work as soundboard woods and
provide builders with unique options to expand tonal quality. The tonal characteristics, as outlined in our previous post, of these woods hold true when they are applied as top woods. Generally these guitars will have less overall volume due to the less elasticity in the wood but have great variety in tone.