A Bridge Quite Close

The violin bridge is an amazing contraption. Like the first violins in the 16th century, they have hardly changed since then. Let’s look at how it works and how to care for it

The bridge is curved to mirror the curve of the fingerboard, with the higher side holding the G string.  Looking past the fancy curves, you’ll notice that the bridge basically has four holes. Each is beneath a string. Vibrations from the strings can’t go through the holes; they have to pass through the solid wood in the shape of a large X, as in the illustration. The sound vibrations are sent directly to the two feet at the bottom. This has the effect of blending the vibrations rather than allowing some frequencies to travel down one side or the other of the bridge.

The two feet are carved to perfectly match the curvature of the violin. This maximizes the transmission of those sound vibrations through the bridge’s feet as the two feet waddle very fast and send the sound into the top wooden plate of the violin. Someone knowledgeable has to carve the feet to fit each individual instrument. This fit doesn’t always happen for cheap instruments, or unadjusted bridges, or bridges that are warped or leaning. Such violins will work but their sound won’t pass into the wood of the violin efficiently, and this will affect the tone of the instrument.

Where the sound goes

There is a lot of tension on the wood of the violin. It is carved with its own curve, and strip of wood called the bass bar is glued underneath the violin top, roughly below the G string. This bass bar pushes up and reinforces the arch of the violin top, against over 40 pounds per square inch of pressure placed on the bridge by the taut strings. All this creates tension on the violin top not unlike the head of a drum, and results in more sensitivity to sound vibrations.

From the top plate of the violin, the sound vibrations travel down the sound post, a wooden dowel held in place by the pressure on the bridge from the strings. This makes the bottom plate of the violin vibrate as well. Sound comes out of both the top and bottom of the violin, and supercomputer models have shown, only in recent decades, that vibrations also travel into the sides of the violin as well. The shape of the f-hole helps project the sound to a greater distance, just as pursed lips force out air at high pressure when you whistle, or when you blow out a candle. Opening your mouth and breathing hard, as you might if you were trying to frost up a cold window or clean your glasses, doesn’t force out much air, which is why folk guitars, with their big round holes, are quieter than jazz guitars which have smaller holes in their tops.

It all starts with the bow on the strings, or the plucking of strings, but the sound would go nowhere without the bridge. Bridges are typically made of maple. I tried out some bridges made of other materials such as redwood, but they really didn’t respond well or sound as good.

Caring for your bridge

Allowing strings to eat into the bridge can dampen their vibrations, so we’re looking for the string to rest on top of the bridge, nestled into a slight groove to keep them in the right position. Since there is so much pressure from the strings, with higher strings exerting much more than lower strings, we need to protect the bridge, especially from the E string. Some bridges have an ebony or plastic protector; most players rely on the little plastic tube that comes with all new E strings to protect the bridge. The E string is thin metal, exerts the most pressure of any string, and vibrates at about 800 times per second. It’s like a little buzzsaw!

It’s important once in a while to make sure your bridge is vertical. Since the bridge is thicker at the bottom, both front and back can’t be vertical. We’re looking for the back side, closest to the player, to be at a 90 degree vertical from the body of the violin. This will make the front side look like it’s leaning back a little. Every time you tune the strings, they pull the bridge a tiny bit toward the fingerboard. To straighten the bridge, take a very firm grip with two hands, grasping the top of the bridge between the G& D and between the A&E, and very slightly and gently pull back toward the chinrest to make sure the back edge is vertical.

This serves two functions — one is to keep the feet in full contact with the body of the violin for the best sound. The other is because if you allow the bridge to lean for too long, it will begin to warp, which is terrible because, first of all, again, the feet lose full contact with the violin, and second, if left too long, the bridge will eventually break.

The placement of the bridge, often set between the f-hole notches, along with the position of the sound post, vary depending on the instrument, and have a huge impact on the quality of sound. I was astonished when someone adjusted the sound post of an instrument and completely removed an annoying overtone the violin was making on certain notes. A good bridge, well carved to match your instrument, can also improve the sound.

The violin, with all its intricate designs, including the bridge, appeared in 16th century Italy in practically the same design we have now. How did Amati figure this out? Did outer space aliens land in Cremona and bring violin designs to Earth? If so, maybe they included some mystical secret of the universe, like the meaning of 42, so you might want to use your spare time figuring that one out!

Whatever happened, we’re lucky it all works so well, so let’s make the most of the violin and its music, and look after its good health.

©2021 Ed Pearlman

One thought on “A Bridge Quite Close”

  1. This was very helpful, Ed. I was able to adjust a slight lean in my bridge, which I hadn’t checked in far too long.

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