COX VIOLINS BLOG

F-holes and Bass Bar

Violinmaker-in-Residence #13

The top of the violin serves a different structural and acoustic function from the back and is designed quite differently. Our overall goal for the violin is to have a body strong enough to be stabile, as light as possible, and stiff enough so that the maximum surface area is transferring vibrations into the air. The design of the top centers around its purpose of transmitting the tension and vibrations of the strings, through the bridge, to the body of the violin as a whole.

The “f” holes are designed to give an area of relative freedom around the bridge so the bridge and top can vibrate more freely when driven by the played strings. The length, shape, and placement of the “f”s all affect this freedom. The “f”s also serve as a tuned release for fluctuating air pressure inside the violin. When the violin produces lower frequencies, air is sucked in and out of the violin and the amount of surface area of the “f”s affects this. In the case of the VSO violin, these design factors are copied from the original and will help give the violin similar playing characteristics.

The Evolution of the "f"s

The Evolution of the “f”s – traced, drilled, carved and finished with associated tools: pencil, borer, coping saw, knife.

The process of cutting the “f”s starts with drawing the design on the top, then drilling a hole through in the lower eye, cutting a rough shape with a coping saw, and finishing and cleaning the cut with a knife. Strad, like most makers since him, carved a fluting in the top arch along the outer edge of the “f”s giving a sculptural lightness to the form. The “f”s, like the human eye on our face, draw our attention and seem to be a gateway into the soul of the instrument.

Fitting the bass bar

Fitting the bass bar

With the “f”s finished the top is graduated to its finished thickness. The top is almost uniform in thickness. The additional strength needed in the center of the top to support the bridge and strings is achieved not through extra thickness, but with the combination of the soundpost supporting the treble side with the stiffness of the back, and the bass bar supporting the bass side by distributing the force throughout the top.

The bass bar is a separate piece of spruce glued under the bass foot of the bridge and extending toward the ends of the violin. I fit my bars with an amount of spring or upward tension under the bridge. This allows for a lighter, more responsive structure. I think of the upward spring in the bar as equal to the downward pressure of the strings, leaving a neutral system that is free to vibrate. The bar is graduated to a shape that gives sufficient strength with minimum weight.   One of the joys of violinmaking is that efficiency of form is reflected in elegance and beauty of line.

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