They are the most common type of acoustic guitar and the category that encompasses more subtypes. They are called "flat tops" or "flat tops" because the covers, both front and rear, are flat. Precisely in this kind of quality guitars caps is critical, as those made with covers best sound compared to those caps plywood.
The material is used for the covers often but mostly spruce wood is different, cedar, mahogany, koa, palorosa ... The masts are mahogany, the fingerboard of palorosa or ebony. The pitch, unlike the classical guitar which is flat, is curved with some radio. The scales are usually of 24.5 "to 25.5" and variable number of dishes, usually 20.
The framework consists of a structure called the "x-bracing," invented by Martin in the 1850s, that unlike the classical guitar. Since the 30s of the twentieth century both the internal structure and the mast is reinforced to allow use of metal strings, unlike the classical guitars using the first three strings of nylon. Adjustable presented trussrod or soul inside the mast, invented by Gibson in the 1920s, helping to hold the tension of the strings and allows you to adjust the curvature of the neck.
The bridges are usually set in a piece of wood, which includes a channel for inserting the bridge itself and some holes where the strings are inserted entangle with plastic pins shaped pin.
