Demystifying the Stringed Instrument Bridge

A simple piece of maple wood might look less important than the showier body, strings, scroll or bow of a violin. But the bridge is critical to the sound.

Among the many parts of stringed instruments – violins, cellos, violas and basses – the bridge might appear to be just a simple wedge positioned there to elevate the strings. It is, after all, just a block of oddly shaped wood that a video game playing student might liken to a space invader character.

But as with the structural bridges we drive our cars over, to get from one place to another, the stringed instrument bridge is an essential conduit. In simplest terms, it transfers vibrational energy from the strings to the body of the instrument, where those vibrations and the sounds they create is amplified considerably.

To understand how this works it helps to know some basics of stringed instrument anatomy. While there are variations, the basic makeup of a violin is largely the same as with the cello, viola, bass, and even the less common viola da gamba.

The bridge creates tension on the strings by pressing them upward. Those strings are anchored from the peg box on the neck (the scrolled end of the instrument, furthest away from the player), and at the other end on the tailpiece (nearest the player’s chin). While this tension holds the bridge in place, perpendicular to the strings and instrument body (some call it the belly), the bridge is not fixed by glue or other means to any other piece. It can be knocked loose if mishandled.

Inside the body of the instrument just below the bridge is the sound post, which is a simple peg positioned there to maintain the structure of the instrument and to transfer vibrations from the top of the instrument to the back of it. This further amplifies the sound.

Do you follow the chain of events that make Tchaikovsky’s 5th Symphony? From the friction of bow-on-strings through the bridge to the body top, through the sound peg to the bottom of the body – and out to the farthest reaches of the concert hall.

A professional violinmaker or reputable violin shop should fit the bridge to a violin. In fact, even a student violin ordered online and shipped to the student will often come with the bridge not in place as it would likely be dislodged or break in transfer. The bridge for a new violin will not even be fitted for placement; it will require refining and shaping from the generic crude, thick and unshaped object that is sent by the instrument maker.

Made of maple, the bridge has cut outs that serve important functions. One is that they have feet that sit on the belly of the instrument body. The violin shop that installs it should form the feet to the slight curvature of the body surface. This enables full contact that transfers the string vibrations most efficiently.

The curly cutouts of the bridge may look ornamental but in fact enhance the sound. If the bridge wood were a solid block the sound would be muffled (these cutouts are referred to as "kidneys").

The top of the bridge, where the strings connect with it, are slightly grooved to hold those strings in place. Over time, the bridge will wear in this area into deep grooves – the effect of all that string vibration – and while a bridge can be replaced, your violinmaker could alternatively add veneers that restore that point of string-bridge contact.

A well-fitted bridge expertly set can make all the difference in the sound of the instrument – perhaps enough that the student will find far greater pleasure in playing the violin than a video game.

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