A thought experiment

[Dave Bagwill]

Okay, you've got an OM top, unbraced. The assignment I've given myself - do not use a soundhole at all. Use a single carbon fiber rod fixed between the head and end blocks in such a way that the braces would not be necessary to keep the top from caving in under string tension: no upper transverse brace in other words. Everything else the same, no more CF.
Now I understand that a greater surface area does not in fact guarantee either more volume or better tone, and that a case has been made that the 'weakening' in the top, caused by the soundhole, and all the gyrations we go through to protect that hole, actually are to the benefit of the guitar's sound.
Could be, but we're just thinking out loud here.

What about this idea? Pic.

[John Parchem]

What would you use for a sound hole. The air needs to come out or you will not have any bass.

[Dave Bagwill]

Just a side-port. My main concern is the bracing.

[John Parchem]

What are you trying to achieve with the design? Louder? more bass? more treble? I have seen designs that are close to it with just a port or set of small ports in the upper bouts probably adding up to the area of a sound hole. Some ovation guitars come to mind. Going to the trouble of Carbon fiber support you might go with two as the strings tension might not be even one side to the other. Two support rods would help avoid the rotation that could be caused. It would be interesting to hear it. why the three ladder braces?

[Dave Bagwill]

As to bass and treble - sanding the perimeter and not locking the x-brace into the lining should give plenty of bass. The ladders are structural, as those long x-brace lets have a lot of work to do, and I thought it might be good to bring in some more of the fundamental of the notes as well. The ladders will inhibit some of the good effects of the X, but might add their own contribution that will make for a richer sound. Maybe.

I would radius all the braces, I think. Probably 5/16" "x" and maybe a full 3/4" high. That can be changed during the chladni process, which should be very interesting. Using that I willl be able to tune the braces (off the body, but still it will tell me much about the top) to get a good visual read and a measured response.

The question is - what does that upper bout really contribute? Is it something we want? That's one reason I'm trying this.

[John Parchem]

Sure interesting. The top and bottom ladders are so close to the very stiff sides I do not think they even count. Yet there is this whole area under the x with no lateral support. May be an nearly horizontal brace closer to the x cross but not touching the x braces. Or just move the bottom one up.

[Dave Bagwill]

Good points. The upper and lower ladders I got from Larrivee patterns, but I see your point.