The wood
The quality of the wood, its procurement, preparation and ageing.
I pay the utmost attention to the choice of the spruce that I use for the preparation of the harmonic case. I extract the raw boards from red spruce, over 300 years old, grown high up on the Swiss mountains.
The cut respects stringent qualitative rather than quantitative criteria. This involves a large percentage of wasted wood. But the utmost acoustic quality can only be obtained with highest quality material and painstaking preparation.
My stock of wood is now more than fifteen years old: I can therefore control its ageing very accurately...