A thought experiment

[Dave Bagwill]

I have not thought about the pinned/pinless thing yet.

[Andy Birko]

Something worth looking into: http://books.google.com/books?id=oejZDX ... ar&f=false

With little or no downforce on the top, you can make it as thin or thick as you like.

[John Link]

I have puzzled over this bracing pattern for days and finally have a vague idea of what it might result in - someone would have to try it to really know something concrete. But this post asks for thinking, so here goes.

Basically, I start with considering the effect of tightening / narrowing of the X. This increases the stiffness in the long direction, which is already stiff because the grain of the top runs this way too. So I would expect treble, "cutting power", and sustain in general to increase, while bass would be stifled a bit. This is what happens in an archtop when the long (more or less "parallel") braces are used instead of the X. It also happens in an X braced flat top with the legs of the X are drawn tighter.

Extending the X so that it runs the whole distance from top to bottom enhances this long direction stiffening effect a little more.

How much of the upper bout would subsequently become responsive is a mystery. But that would be very interesting to learn about. If it does become responsive, it might affect the optimal location for the bridge.

[ken cierp]

Batson does/did make guitars with this set up -- to my ear -- not good

[ken cierp]

Over under Bridge -- to my ear there is something missing? Pretty thin, where's the resonance?

[Dave Bagwill]

I'm not fond of that sound at all. I wonder if a typical x-brace would not have provided a fuller sound?

[Ken Hundley]

I had a similar thought and have built a couple guitars to test the theory. 2 have actually been completed this way, but were not my best efforts. I also think I was trying too many innovations at the same time....no sound hole, new bracing pattern, Sitka/Wenge laminated braces, dual sound ports, the list goes on. Below are the bracing patterns I came up with. I wanted to reduce the number of braces, and also make them lighter/stronger to free up the sound board. I also wanted to use more of the soundboard as a sound producing surface, thus eliminated the sound hole.





The laminated braces proved more flexible than a sitka brace, but stronger. I would like to try to repeat this guitar once with sitka braces in this pattern, and again with sitka braces in a more traditional x pattern, and see what really contributes to the unique sound this guitar and a Padauk version of it produce.





I used a pinned bridge, and the guitar is based on an OM size. Trebles are very bright, very crisp, but not overwhelming. Base is very low, almost breathy, coming out of the larger port facing the player. The top can be over driven, almost sounding muddy in the mid ranges as the player. Sitting in the audience and listening to someone else play, however, it has a larger presence than the rosewood jumbo I built years ago, still a cannon of a guitar. Again, though, played hard, the guitar can be overdriven. I can't tell if this is the brace pattern or the laminations that contribute to this. As cool as the braces look, I am not convinced lamination is worth the effort. I do still feel moving the sound hole off the top gives these guitars far more presence, basically allowing more sound to reach the listener with the same amount of energy.

The idea of the two sound holes is derived from the (admittedly qualitative) improvement of the sound of a regular guitar modified with a port. By moving the hole off the top, I get more surface area emitting sound. By only using the port as the opening, I lose whatever potential benefit a port gives me. I chose to put a smaller port on the cutaway, and there is a difference when applying packing tape over the smaller hole. I would like to try this approach with more standard bracing on a 12 string, which tends to loose low end response due to, in my opinion, stiffer bracing because of the extra load on the top. We'll see how it turns out, will be a couple years in the making.