This week I have been adjusting a viola I made last year. The sound was too much in the treble range for my taste and I wanted to bring more bass across all four strings. To achieve that I’m adjusting the bridge together with other changes to the viola.

With traditional methods I look at the quality of wood, thickness, height and overall cutting of bridge. Now with my laptop and a ‘Piezo sensor’ I’m able to check the tuning or frequency of the bridge. In the other words the overall brightness or mellowness of the bridge.

Above is the set-up I use. The bridge is held gently by the feet in a heavy vice to reduce extraneous vibrations. The sensor is resting against the upper edge of the bridge. The opposite edge is plucked. The sensor together with the computer software registers the frequency.

The top screen shows the ‘volume’. The lower screen shows the frequency and the various peaks that make up the sound. The tallest main peak is the one I’m interested in – and it showed a fairly high frequency of over 3000 Hz.

By carving wood away from the bridge I’m able to raise or lower the frequency of the bridge. In this case , I plan to remove a touch of wood from the waist of the bridge to lower the frequency and therefore reduce the overall brightness of the viola.

Recently on another occasion, working on a violin, this technique helped me decide that the bridge was in fact just fine and so I focused my attention and adjustments elsewhere.

(In setting up my bridge tuning rig I assisted by a select and generous group of North American violin making colleagues)