Stringed instrument having an elongated neck member optionally including a fingerboard, with a plurality of frets fixedly positioned at predetermined spaced locations along the neck. The frets include a tang and a mushroom shaped crown, each positioned and secured in a corresponding fret slot formed in the neck. The neck member includes a carbon fiber based support member that can be T-shaped. In its method aspects, the neck can be straight and of neutral strain or a desired backbow/underbow or curvature in the elongated neck member is created, such as by introducing a carbon fiber T-bar support member in the neck member in a “neutral” state while clamping the neck member in an underbow shape, or forming underbow directly into the finished neck in which a carbon fiber T-bar is already present, and then introducing crown bar style frets to wedge the neck back to an optimum playable shape.