To enhance the stability of the neck, all of my guitars include the following special features: an independently supported fingerboard extension, a Spanish foot and A-frame bracing system to support the headblock, and a Spanish V-jointed headstock.
In addition to a two-way adjustable truss rod, two carbon fiber rods run parallel to the outside taper of the fingerboard and extend all the way from the headstock to the ends of the fingerboard extensions to support the entire neck and fingerboard.
Inside the body, a well developed A-frame bracing system supports the neck and headblock. The soundhole braces continue through the brace just above the soundhole to form the A-frame and are terminated by mortising them into the headblock. A cross grain patch of spruce is then added to the inside area of the A-frame for additional reinforcement.
The brace just above the soundhole receives much of the load from the neck and is reinforced with carbon fiber. Not only is carbon fiber extremely stiff for its weight, but more importantly it will never deform over time as even well quartered wood will do.
For even more support, a "Spanish foot" is mortised into the headblock as a lever to help prevent rotation about the headblock. As one can see, the neck and its attachment to the body comprise an entire system utilizing both traditional methods and new materials and ideas to provide unsurpassed stability.
Finally the headstock is attached to the neck shaft using a Spanish V-joint. This is a classic traditional design that is in fact stronger than a one piece neck. Not only does the grain of the headstock have the proper orientation in this design, but the tension of the strings work to pull the joint together.
XTF bracing is a novel soundboard bracing system developed over the past several years by RS Muth Guitars. The initial idea was to incorporate aspects of classical fan bracing in a steel string guitar while recognizing differences in the amount of energy applied to the soundboard by steel strings. "X" designates the traditional X-brace, "T" designates the tunnel braces, and "F" designates the fan pattern in the lower bout.
XTF bracing is a hybrid system that accomplishes several tasks. The "tunnel" braces provide additional support to resist string torque while allowing the entire top to pump more freely. This results in more power and better bass response in the guitar. Fan braces intimately coupled with the bridge plate are used to support the lower bout. This system results in the enhanced expression of the tripole vibration mode typically found in nylon string guitars. This mode of vibration is very efficient and helps provide power to the trebles and higher harmonics. This results in rich fat trebles and greater balance throughout the frequency range.
Overall this system can be more lightly built since it effectively distributes the forces throughout the soundboard. Unlike many other systems, it does so in a way that takes into consideration the various vibration modes of the soundboard, especially the underutilized tripole mode. As a result, XTF bracing not only offers structural improvements, but offers a sonic advantage in terms of unprecedented tonal balance, clarity, sustain and response with lush trebles, a nuanced midrange, and a strong well defined bass.
Properly integrating the bridgeplate with the fan braces is very important. In order to effectively resist excessive bellying in the lower bout, the fan braces need to be at their greatest height immediately behind the bridge. This is achieved by carefully overlapping the ends of the fan braces over the bridgeplate.
All RS Muth guitars now include double sides in which two thinner sides are glued together to provide an ultra stiff rim to receive the soundboard and back of the guitar. This not only enhances the sonic efficiency of the guitar but provides further support in the upper bout to resist rotation of the neck.