Views on the Bridge
In the second of two articles on set-up, Joseph Curtin investigates the acoustical role of the violin bridge and the interconnected relationships between mass, frequency and resonance
The bridge and soundpost are ground zero for set-up. Where the post is a simple, timeless design – a spruce rod whose important parameters are mainly its length and position, the bridge is a complex structure whose design has changed dramatically over the centuries, and whose important parameters are, after several decades of scientific research, only now becoming clear. This article outlines some of the experiments done at the VSA/Oberlin Acoustics Workshop, and the light they shed on both the evolution of the bridge and the possibilities for optimising violin sound via ‘bridge tuning’.
Because they are so often replaced and then discarded, there is scant evidence charting the bridge’s evolution. That said, the five bridges depicted in Figure 1 suggest a line of development. Comparing the Stradivari bridge (1a) with the Hill bridge (1e), the upside-down heart set beneath the waist of the former has become the upright, blunted heart above the waist of the latter. The Baroque design has, in effect, been inverted – the way the subject of a fugue might be. François Tourte did something similar when he inverted the camber of the Baroque bow and gave us the modern stick. The inversion of the Baroque bridge design allowed the modern bridge to have a relatively narrow waist with a relatively large amount of wood above it. The acoustical implications of this will be a central focus of this article.