Soundboards- the soul of the dulcimer
Today I finished rough sanding 14 soundboards that were previously bookmatched and glued together. These will have more impact on the final tone of the instrument than any other component. Four woods are represented- Sitka Spruce, Western Red Cedar, Yellow Cedar and Port Orford Cedar. Neither Yellow Cedar or Port Orford Cedar are true cedars. They are both members of the cypress family which have found favor in flamenco guitars.. The Western Red Cedar soundboards are destined for my steel string dulcimers while the rest are all candidates for the nylon string dulcimers. Aaron and I will be testing a number of them to make the final selection.
At this stage I suspend the soundboards vertically and tap them to get a hint of their acoustic properties. This method of evaluating the "tap tones" has a long history in lutherie. Based on the tap tones, two of the soundboards have been set aside for baritone dulcimers. All of them are thicker than their final size. From this point I will measure the longitudinal and transverse stiffens of each soundboard and progressively reduce the thickness on my thickness sander ( a few thousandths of an inch each time) until I reach the stiffness that experience has shown will provide the desired sound profile. Since no two pieces of wood have the same characteristics (even of the same species) it is critical to perform this evaluation and not just sand to a given thickness if you want to reduce instrument to instrument variability. It's a lot of time devoted to soundboard optimization, but it's some of the most important time spent building a fine instrument.