The Soundpost
by
Otis
Tomas EVERY FIDDLE PLAYER
knows that the soundpost, a small stick of spruce
wedged between the top and back plates of a violin,
plays an important role in the performance of the
instrument. But simple as it is, the post's function
is quite complex and little understood. About 1/4" in
diameter, the soundpost stands upright just behind the
treble foot of the bridge. Often called the 'soul' of
the fiddle, its main purpose seems to be to harmonize
the vibrations of the top and back. Structurally, a
fiddle's arching alone can support the bridge, but
played without the post, its tone is hollow and rough
sounding; replacing the post puts the tone back into
focus. The post's
resistance to the treble foot of the bridge also
serves as a pivot by which the bridge's vibrations
pump the bass bar. The relative position of the post
to the bridge, ff-holes, and bar can be critical.
Moving the post toward the bridge usually makes the
tone tighter and more focused, whereas going back from
the bridge makes it more open and hollow. Placing a
shorter post further toward the edge can give more
depth to the bass strings. A longer post nearer the
centre can often, conversely, even out the tone of the
strings. These are only the
most basic of generalizations. Other factors such as
the tightness with which the post is put into place,
the mass of the post itself, the relative tuning of
the top and back plates, and the shape of the archings
all have a bearing on how the post relates these
variables. It is impossible to
give definite rules for proper soundpost adjustment,
but there are a few rules of thumb that can be a good
starting point: 1. The post should
stand behind the bridge by a distance equal to the
thickness of the top at that point. 2. It should be
aligned with the treble foot of the bridge in the same
way the bass bar is aligned under the left foot of the
bridge. 3. It should stand
vertically, its endgrain aligned perpendicularly to
the grain of the top, ends fitting perfectly to the
plates, and placed with only as much pressure as
necessary to keep it from falling when the strings are
off. One should beware of
tinkering unnecessarily with the post as every
movement will require a period of readjustment to the
new equilibrium which has been set up. Also, beware of
damaging the ff-holes. Try always to work through the
treble side to keep any accidental damage to one hole.
Especially on historical instruments it is important
to leave the left hole untouched, as evidence of the
maker's artistry and intent. by
Otis
Tomas
ast upddate 8/6/98