Sound post

In a string instrument, the sound post or soundpost is a small dowel inside the instrument under the treble end of the bridge, spanning the space between the top and back plates and held in place by friction. It serves as a structural support for an archtop instrument, transfers sound from the top plate to the back plate and alters the tone of the instrument by changing the vibrational modes of the plates.

The sound post is sometimes referred to as the âme, a French word meaning "soul". The bow has also been referred to as the soul of these instruments. The Italians use the same term, anima, for this.

Sound posts are used:

Sound post adjustment

The position of the sound post inside a violin is critical, and moving it by very small amounts (as little as 0.5mm or 0.25mm, or less) can make a big difference in the sound quality and loudness of an instrument. Specialized tools for standing up or moving a sound post are commercially available. Often the pointed end of an S-shaped setter is sharpened with a file and left rough, to grip the post a bit better.