Acoustic Guitar Construction

Seems it would lend itself to an adjustable configuration. I played a Charles Fox with a raised fingerboard and it felt -- well, not comfortable.

Violin family instruments and archtop guitar soundboards are braced very differently from flat top guitar soundboards. The shoulder brace/ upper transverse brace/ whatever you feel like calling it brace that runs above the soundhole puts a big samper on how much the area above it can vibrate anyway. An archtop instument does not have the aforementioned brace and instead utilizes two long tone bars that run parallel-ish to the string path. Thus, in theory, more of the soundboard can vibrate freely if the FB does not touch the top. On a flat top, it seems to make little difference.
You could always try touching the area next to the FB extension on one of your guitars after strumming a chord to see what happens. I know for sure when I touch the soundboard behind the bridge on my guitars it makes a BIG difference in the sound of the guitar. Same with damping the back against my ever expanding stomach. Less touching means nicer tone to my ears. I have never ever touched the soundboard above the soundhole to see what happens.
Classical and Flamenco builders generally only consider the area of the sound board that is aft of the big brace they place below the soundhole to be the key vibrating area. And we all know that classical and flamenco players are very picky about tone, don't we? If you didn't know that before, you do now.
Anyway, this is all a moot point because Somogyi said the area above the UTB is not important in sound production so...end of discussion. I'm kidding of course, but he does seem to know a fair bit about guitar construction.

I would submit that Somogyi's statment about the upper bout not contributing to sound quality is based on the narrow view of common convensional guitar structure -- without question expanding the vibrating sound-board surface area will have an effect on the instrument's audio output traits. I think Dave wants to know if those changes are good or bad and worth the effort? McPhearson's are amazing guitars but they have many different design features as well as a raised FB extension.

I would suggest that my mention of what Somogyi thinks was tongue in cheek. He might build guitars that sell for $30,000 but that does not necessarily mean everything he says is Gospel. He does know a fair bit about building a decent guitar though. But saying that everything above the UTB is just a wasteland? I don't agree 100%. He never said it was a wasteland, those were my words, but he does say that area does not contribute to the sound all that much if at all.

Your comments are "spot on" Tony -- I do respect Somogyi, he's a good one, but truth is that some of his comments and even so called engineering principle demos are just opinions (not facts) and over reach, this tends to turn off some of his peers.

As normally constructed - that is, with all the materials devoted to keeping the soundhole from collapsing, the UTB and all that stuff - it's no wonder the upper bout is not allowed to do much but be a defense against an explosion; asking it to also contribute delightful sound as well is asking too much.

Move the soundhole to a more secure location though, and I see no reason the otherwise heavily carpentered upper bout, freed from its restraints, cannot do whatever it is called upon to do within its capabilities - which is up to the luthier.

I'm getting close to closing the box on an A frame guitar with an offset soundhole - 2 holes actually, since I spread the 'A' as far as I could within the limitations of the saddle width and that meant, if I wanted to achieve the soundhole size I sought, I had to divvy it up over two smaller holes - in any case, I'm looking forward to seeing what quality of sound I can get out this. The volume will be less because of the soundhole placement, but is that really a concern? If the sound is good, I'll put a mic in front of it and it will be plenty loud> :-)