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If you can get hold of William Allen's article on air resonances in 'American Lutherie #1', or the first 'Big Red Book' it will tell you a lot about what to expect. But not everything. One thing in this context is that, as you move the hole away form the middle of the box the 'Helmholtz' air pitch drops. Several people have shifted the hole up into the upper corner on the bass side to drop the 'main air' resonance down to the region of the lowest played note, expecting better bass. I'm not sure that pans out. However, you could shift the hole up and make it bigger, which would keep the 'air' resonant mode pitch the same, but should alter the high frequency response. I would consider an Ovation a poor model for what to expect on a guitar you made: they do too many things differently.
It's likely that a dozen small holes spread out within a five inch circle would give the the same 'main air' pitch as one five inch hole. I've noticed that putting a 'rose' or 'feedback buster' in a sound hole may not drop the air pitch, even though the total area of the holes is smaller. What does happen is that a lot of little holes will have much more 'edge' in relation to the area than a large one, so there's more drag as the air flows in and out. This increases the loss and lowers the output of the 'main air' mode. That's how feedback busters work: with more loss you need to use higher gain to initiate feedback.
I once made a guitar with two smaller holes in the upper bout instead of the usual big one in the normal place. This was at the request of a customer, who wanted to get more vibrating area in the soundboard. Basically, I changed the upper transverse brace into a shallow X, and put the holes in between the arms of the X. Structurally it worked great. There was a problem with the sound, though.
There's a 'crosswise sloshing' type of resonance in the upper bout of the guitar, usually up around 700 Hz, iirc. Normally you don't hear much from it, since the normal hole is in the middle, where there's no pressure change to speak of in this mode. The two holes in the corners picked it up, and shifted the pitch a bit higher in the process. Because they were radiating sound from that mode out of phase they tended to 'beam' it out in two directions at an angle to the center line. It turned out that the player would get a pretty good dose of this, which made any note that had an overtone in that range sound loud. Naturally, you'd back off on those notes. The result was that some listeners found the tone 'uneven' out front: it wasn't so much a problem with the guitar itself, but it's hard to not back off when a note sticks out so much.
There does seem to be a complicated interaction between the shape of the guitar, the way the walls vibrate, and the normal sound hole location that can contribute to the timbre. Basically, it seems as though having the hole in the usual place, just above a pronounced waist, which is itself above the center of length of the box, and having the walls of the box, particularly the top and back, able to vibrate, tends to split the lower order air and wood resonances into multiple peaks. You can often find two 'A-0' Helmholtz-type resonances, and two 'A-1' "lengthwise sloshing" modes that couple with the top 'long dipole', so that it, too, shows up at two pitches. All of this adds quite a lot to the complexity of the output of the guitar, which is generally a good thing, since it's what makes the sound interesting. Shifting the hole up to the upper corner kills this, and I often don't see this sort of splitting in Dreads, which don't have a pronounced enough waist, apparently.
In short, there seem to be reasons behind tradition.
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