The back plate
The Viennese bass can be considered as the last stage in the evolution of the viola da gamba that is still in use today. All Viennese basses have a flat back instead of a carved one. A flat back saves time and material, as there is no need to carve it from a big block of maple. But good back braces need to be made from perfectly split and seasoned spruce.
Traditionally, Viennese basses used to have three braces, the central bar being the one supporting the soundpost. Some of the backs had graduating thicknesses, and most of them were not just flat but bent in a convex shape. This convex shape gives a lot of strength to the complete structure; however, when not done correctly, it can tear the whole instrument apart.
Although it seems rather straightforward, a lot of skill and care goes into making a stable and well-functioning flat back. First of all, the enormous pieces of wood need to be very old and relieved of any internal stresses. When we make our basses, we cut the pieces to a thickness of about 15mm and store them perfectly flat. After ten years the wood has moved in all directions and the only way to plane these pieces perfectly straight is by doing it by hand. After jointing those, to ensure the pieces stay tension-free, we keep them stabilised even longer between thick MDF plates, until they are ready for the back braces. All those steps – the thicknessing, the jointing, the gluing and shaping of the bars, and the making of the bend – have to be done in a very precisely controlled environment, with particular attention given to the temperature and air humidity. This way, we end up closing the instruments with minimum force, and can ensure the backs remain crack-free.