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Innovative Custom and Semi-Custom Electric Guitars

 

TorsionLogic™

 

The Long Version, or What the Hell? And Why?

Most players are passionate about one type of construction or another. Set-neck, neck-through and bolt-on styles all have their proponents and critics, and each style has its advantages and disadvantages which have been debated for decades.

As a custom guitar builder, I have built all three styles at one time or another and have come to prefer the bolt-on design. I feel that the neck-through structure, while eliminating the high-fret access problem, also eliminates the tonal influence of the body wood because the tuners, bridge and pickups are all mounted to the neck wood. Body wood is usually softer than the neck wood(s) and can help enhance midrange frequencies, but only if string-related hardware is attached to it. In a similar vein, the set-neck leaves a very thin layer of glue between the neck and the body, which I believe can affect the wood's ability to resonate freely.

These opinions have recently been validated by painstaking research. There has been a long-standing assumption that a neck-through design provides superior sustain, with set-neck and bolt-on following behind in that order. But recent research by noted luthier R.M. Mottola, published in the Fall 2007 issue of American Lutherie, indicates that the reverse is actually true: the bolt-on design produces better sustain and better harmonics than either neck-through or set-neck designs. Mottola states, "Overall power around the fundamental (329.628hz) as well as second and third harmonics is highest and sustains longest for the averaged signal from the bolt-on neck configuration of the test instrument..." (2007, #91, p. 55). The test instrument used was a purpose-built, 2-string solid-body test bed, designed specifically to eliminate as many independent variables as possible.

Finally, both the neck-through and set-neck designs are permanent; if you break the neck, your guitar goes from being a musical instrument to being nothing more than a doorstop or a sad wall decoration.

One day I was working on a design for a customer. He had specified a bolt-on neck with 24 frets, but I wasn't willing to sacrifice upper fret access and a smooth neck/body transition. The design problem was this: easy upper fret access means an extremely deep cutaway and moving the neck heel farther along toward the body. Deep cutaways alone can't do the whole job if you don't get the mass of the heel/body joint out of the way as well, so both are necessary for effortless upper-neck access.

So my first thought was to build a significantly longer neck which extends well past the end of the fretboard, effectively creating a tenon which would reach much deeper into the body, moving the neck/body joint farther back as a result.

neck & body

This, of course, is not a new idea. Many fine set-neck guitars are built this way. But I realized that since the neck pickup is placed quite close to the end of the fretboard, routing the pickup cavity would cut most, if not all the way through the tenon itself, leaving the neck with little structural support and more importantly, little interface with the body meaning less resonant coupling.

pickup rout profile

I could make the tenon thicker, but if I made it thick enough to be structurally solid, I would be headed into neck-through territory and once again reducing the influence of the body wood. Not what I want.

As I mulled over this design conundrum, I had a bit of a revelation. Instead of mounting the neck in the traditional pocket routed in the front of the body, why not mount it in the back? This would enable me to incorporate all the best features of each design; neck attachment deeper into the body, a long tenon for plenty of contact area between those two different but complimentary pieces of wood, and no glue to interfere with resonance. In addition, the string tension and torsion pull the neck into the body instead of trying to pull it out. This means fewer screws are needed to keep the neck tight in the pocket. Logical, neat, elegant. TorsionLogic!

For more information about the actual construction of our TorsionLogic necks, click on the link below.

Ford back naked

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