Double bass construction, considerations
For our instruments we often use woods not common in the classic Lutherie and that may be considered not appropriate. On the contrary, it is the classic Lutherie itself that helps us understanding that our belief is correct.
Antonio Stradivari (as mentioned in the book "I segreti di Stradivari" by S.F. Sacconi) manufactured one third of the violas and almost half of the Cellos using poplar or willow wood. This has a logic explanation. Maple is the very best wood for violins because of its extraordinary compactness and specific weight and also because you can give the back a very thin thickness in order to guarantee an excellent sound effect.
For instruments of Grave registry such as the double bass in particular, the most appropriate woods are those of less compactness such as the black poplar, the chestnut and even the cypress that are better for the low frequencies such instruments have to reproduce. Then, when we tune up the note produced by the wood during the digging of the inside part, we realize that for reproducing the same note using the maple wood (especially if flamed and compact), we should make a very thin thickness part that would hardly bear the high sound a double bass must dissolve. In saying this, we don't mean to state that marple is not appropriate for manufacturing cellos or double basses.
Experience teaches us that inside a trunk the resistance of fibres is different depending on the part of the trunk they are located, north or south side, or close to the soil and so on. What we mean to say is that we choose very carefully a wood for our instruments, considering all the parameters such as: dimension of the instrument, flat or curved back or if the instrument is for classical or jazz music.
>Neck and fingerboard
Unlike the common though, the neck and the fingerboard of a bowed string instrument are fundamental either for the agility of the performance either for the sound effect. For the Double bass where all is big, this is even more important. According to the agility of the performance, 3 main aspects are essential: the dimension of the neck, the bending of the fingerboard, the hardness of the strings.
The cooperation with Master Franco Petracchi, Andrea Granai, Walter Garosi and Silvia Bolognesi was very important for us in order to define the dimension and the bending of the fingerboard and thanks to them we gained experience and improve our work. The fingerboard for Double bass, as known, must have a slight bending on the lengthwise side as to prevent the string to "turn" on itself once touched. Often instruments are manufactured with a too bended fingerboard with the consequence that the strings are higher on the central part of the fingerboard other than on the lower part. This is a big problem for musicians either for the physical effort in having the string too distant from the fingerboard and either for the limits in playing very fast parts.
A bad intonation is also the result of the deep distance between the string and the fingerboard in the central part due to its high bending. As for the hardness of the strings, this is often caused by an extreme backward bending of the neck, determining a too big angle of the strings on the bridge and increasing too much the pressure of the bridge on the top. This defect causes damages to the instrument for the over pressure it cannot dissolve and this makes also the strings become harder because the belly is stuck in its flexibility. We can solve this inconvenience reducing the angle of the string on the bridge in making the tail piece upper with a thick under the string that keeps it in tension. In solving this problem, it is very useful to adjust the anima in order to dissolve the over pressure of the bridge.
When we make our instruments, before determine the angle of the backward bending of the neck, we take into consideration the following: The belly arching, its thickness and if it is a double bass with flat or curved back, In order to obtain a great handiness during the performance and the best sound effect.