All our Instruments are built according to the old Spanish technique
The basic structure of all Thomas Guitars, are made by employing the old Spanish method of using a solera to glue the unfinished neck with the intended angle to the soundboard. Then the bent sides are glued with individual wooden blocks to the top, and finally the back is fitted.
This method has some really great advantages both tonally and structurally.
We make laminated quarter sawn necks, and a flat sawn block to connect the neck and foot. This block prevents the foot from being pressed out of the back over time due to wood shrinkage and expansion from varying temperature and humidity changes.
Before gluing the fretboard we install two carbon rods and a stainless steel truss rod. The carbon rod simply stabilizes the neck and prevents the neck to rise and bend too much over the years. The wedge between top and fretboard has some great advantages. Structurally because the fretboard can be thinner, and by reducing the weight of the neck the guitar gets better balanced and at the same time the upper frets are a lot easier to play because the fretboard is elevated in the area of the soundboard
The fretboard is made of a quarter sawn piece of ebony or rosewood
The slots including the nut, and the shape are cut by CNC. That guarantees the perfect position, hides the fret ends and allows the nut to become part of the fretboard for better sounding open strings.
We sometimes use different woods but we still favor Alpine Spruce from our area as these are exactly the same places where the old master luthiers Stradivari and Guarneri got their wood. Since 2010 we´ve been chosing the trees in the summer and cutting them at a particular time in the winter considering the phase of the moon, following the rules of the old grand masters. The wood is directly cut into pieces and naturally dried. The spruce cut after these simple rules becomes harder and lighter and tends to move less than ordinary cut spruce.
ABOUT FOUR PIECE TOPS
One of the most difficult tasks of luthiery is to obtain a constant tone quality. The easiest way to achieve that is to use the same wood with the same specs, but of course it is nearly impossible to get two similar Tops, even within a single tree.
In 2015, we decided to build a steel string double top guitar. Our goal was to find out how the tone is affected and if that change would be a possibility to create the sound we were looking for in an easily reproducible way. We used the common honeycomp - method as invented by Matthias Dammann with the inner and outer layer in moonspruce.
Since this guitar served as a prototype and we refused to waste two of our nice tops, we decided to assemble the inner layer of three spare parts. Surprisingly, we found out that the more inner layer was stiffer and homogeneous than the outer layer – which brought us to the idea of using only the best part of each board for cutting tops. No sapwood, no wider grain from the early years of the tree, just the „filet“ in-between.
The trees we cut are about 250 years old and 85cm in diameter so if you cut the sapwood and the core and the wider years from the inside, you get about 10 to 14 cm wide – „four-piece-tops“, which are very constant in stability and weight.
The X – bracing we use is not just a copy of an old Martin Guitar, but has rather evolved through the years with our ideas of sound and stability. Each model has a particular bracing that is shaped to a certain tone and stiffness.
We bend our sides on a self-made bending machine with a very accurate temperature limit for each different kind of wood and “bake” them until they become harder and stay in shape.
One advantage of using a solera for construction is the tension free assemble of the sides and soundboard. After being bent the sides are trimmed and glued into the slots in the heel, and then fixed to the top with small individual blocks.