Acoustic Guitar Construction

Thank you again gentlemen for your help. John - I can’t help thinking that if forward shifting produced a much better sounding instrument then it would be the industry standard by now rather than the exception, I’m guessing structural stability must be a concern with more of the lower bout unsupported. I’ll probably stick with the standard bracing with this one but I’ll decide once I see how stiff the top is once it’s at it’s rough thickness. Thank you for the links to voicing, it’s definitely something I need help with as I’m still not sure what I’m listening for when tap tuning. My last build turned out well, but I’m sure I could have improved the sustain if I understood the voicing process more, I’m still very wary of going too far when thinning a top, so probably leaving it a little thicker than I could have got away with.

Will - Thanks for info and X location measurements, very useful. I’ve always fancied a making a smaller 12 fret guitar, they must be nice and comfortable to hold, maybe my next one.

Neil,

I can appreciate your reluctance in soundboard thinning, it's better to creep down to scary thinness. For bracing, the height's far more critical than the width. But board and brace are both are part of the equation.

And again, for what it's worth, my friend here who used to work at Elderly Instruments told me that they get inundated by amateurs like me wanting them to sell their guitars. He says that they almost all look like exquisite works of joinery and splendid lacquer but uniformly don't sound very good.

I'm also able to enjoy the advise of fellow artist and member of this forum, John Link, who lives about 30 miles west, for the soundboard dimensions in my previous comment as a point of departure.

Somewhere on the Net I found somebody who said about soundboard thickness, “Wah, just plane 'em down until they rattle like sheet metal”. I'm not doing that yet, but the point is the top has to move to pump sound. It can be thin but if the bracing is too stiff, where are you? Like Peter said, all the parts have to play together. Bracing is scalloped to decrease stiffness.

Guitars are like paintings, as statement; it's all hanging out there for all to see or hear, nowhere to hide. For a guitar to really sing it pretty much needs to live at the ragged edge of self-destruction.

In Guitarmaking-Tradition and Technology, Wm Cumpiano states that the top should be 'quenched'. The top should be thinned until there is no discernible note when tapped. I believe this the same thing Kent Everett talks about in his video. If there is a note when the the top is tapped, it will be too stiff to be responsive when braced. It will still sound like a guitar, but may not have much sustain either.
Remember also, the big companies do not want warranty work to eat at their bottom line. When Country and Western players began putting heavy gauge strings on their guitars and played them hard (ie. beating the crap out of them), Gibson and Martin had to make some adjustments or they would go broke. The two most notable changes were, shifting the X-brace back and ramped braces rather than scalloped. The guitars were built 'heavier' overall. If you ever pick up an old guitar from the 1920's or early '30's, thy are usually very lightweight. This is why pre-war Martins are prized by many players. Lightweight and responsiveness died in the 1940's. Now, Somogyi and others have gone back to making guitars in the old style. These guitars are selling for very large prices. At the same time, we are using lighter gauge strings and have amplification.