
In a
string instrument
In musical instrument classification, string instruments, or chordophones, are musical instruments that produce sound from vibrating strings when a performer strums, plucks, strikes or sounds the strings in varying manners.
Musicians play some ...
, the sound post or soundpost is a
dowel
The dowel is a cylindrical shape made of wood, plastic, or metal. In its original manufactured form, a dowel is long and called a ''dowel rod'', which are often cut into shorter ''dowel pins''. Dowels are commonly used as structural reinforceme ...
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.
[David D. Boyden. "Ame", '']Grove Music Online
''The New Grove Dictionary of Music and Musicians'' is an encyclopedic dictionary of music and musicians. Along with the German-language '' Die Musik in Geschichte und Gegenwart'', it is one of the largest reference works on the history and t ...
'', ed. L. Macy (accessed May 20, 2006)
grovemusic.com
(subscription access).
Sound posts are used:
* In all members of the
violin family
The violin family of musical instruments was developed in Italy in the 16th century. At the time the name of this family of instruments was viole da braccio which was used to distinguish them from the viol family (viole ''da gamba''). The standa ...
* In some members of the
viol family
* In some
archtop guitar
An archtop guitar is a hollow acoustic guitar, acoustic or semi-acoustic guitar, semi-acoustic guitar with a full body and a distinctive arched top, whose sound is particularly popular with jazz guitar, jazz, blues, and rockabilly players.
Typic ...
s
* In other string instruments
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.
Soundpost adjustment is as much art as science, depending on the ears, experience, structural sense, and sensitive touch of the luthier. The rough guidelines in the following section outline the effects of various moves, but the interaction of all the factors involved keeps it from being a simple process. Moving the sound post has very complex consequences on the sound. In the end, it is the ear of the person doing the adjusting that determines the desired location of the post.
Effect of position on the instrument
Moving the sound post towards the fingerboard tends to increase brilliance and loudness. Moving the sound post towards the tail piece decreases the loudness and adds a richness or hollowness to the tonal quality of the instrument. Moving it towards the outside of the instrument increases brightness and moving in towards the middle of the instrument increases the lower frequencies. There is very little room to move the post from side to side without fitting a new post (or shortening the existing one) since tension (how firmly the post is wedged between top and back) plays an important role in tone adjustment. Perfect wood-to-wood fit at both ends of the post is critical to getting the desired sound.
image:Soulpost2.gif
See also
*
Bass bar
References
External links
Musical Instrument Makers ForumViolin Discussion ForumSection on building and maintaining violins
{{Authority control
String instrument construction