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I have a body style that gives me 14 frets clear and yet the bridge is at the middle of the lower bout. I have read that this is ideal for moving the top. To do that I have to use 00 specs, not shape.
I am thinking for enlarging the body to say 000 specs to get more interior space in the hopes of getting more sound. Doing that will move the bridge up and away from the center of the lower bout. That is the way most guitars are so no doubt it would be ok.
My question is this, is a central bridge better at making sound or will more interior make more sound? No point in making a bigger guitar if it is not producing more sound. I define that as volume which allows the qualities of the instrument to be better heard.
I am a lurker so I want to take this opportunity to thank all of you that share so freely from your experience so that beginners like me can enjoy and learn. You should see my files. My computer is mostly a cabinet for guitar info.

its a combination of things. Martin uses the same shape on the 14 fret 000 and OM. On the OM the bridge is lower on the body. There are plenty of things that can be done to increase volume and tone .
There is no one answer for your questions and you will get many opinions on this. A lot will depend on scale length , bridge height , and braces.

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John Hall
blues creek guitars
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You Don't know what you don't know until you know it

I thought this might be of interest:

http://www.lutherie.net/12-14-evolution.html

I would also question that the notion that the bridge should be in the center of the lower bout for the "best" sounding guitar. If you look, most instruments with soundboards have the bridge placed in non-central location. The best (or worst? ) example of this would be a banjo. It would be very easy to design one such that the bridge would be right in the center of the membrane yet banjo makers choose to place it off center always. That's also true of Violins, Guitars, Pianos, Mandolins etc. etc. I suspect that placing the bridge off center actually might allow more displacement in the monopole and possibly helps the even numbered modes vibrate asymmetrically which should be better for volume and tonal interest thought really I'm just speculating on these points.

Now, placing it in the center of the lower bout is definitely asymmetrically placed in terms of the whole guitar but If we figure that most of the sound is produced in the lower bout....(ducking for cover)

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Good points, Andy. Also, at least on X braced guitars, you have to consider that the whole triangle of bridge to X intersection is more or less a rigid unit... so perhaps the 12 fret neck on 14 fret body position is in fact more centered between upper brace and tail, as well as the lower bout?

Another point is waist tightness... to me, the 14 fret position seems much more logical on a dread. The waist is so wide, there's still plenty of space to the sides of the bridge for it to move freely. On something like an L-00, the bridge wings are quite close to the edge... seems awfully constricted, especially in the cross dipole/side to side rocking motion, but also motion of any sort. At least you'd probably want fairly flexible and/or smaller bridge wings, and position the X so it's closer to the center part of the bridge so you still get good coupling.

Here are some points in favor of 14 fret, though:
Caving into the soundhole causes more trouble than bellying up in the lower bout... thus more structure is needed above the bridge, which restricts movement there.
The waist makes the above-bridge area smaller and thus able to move less air anyway.
There's a big hole in the middle of it... the area that would get maximum excursion to move air in long dipole mode actually moves none.
Bottom line, the north quadrant has many reasons not to produce much sound, so you might as well make it smaller and try to get the rest of the top moving more. Question is, does having the bridge in the 12 fret position in fact allow you to get the rest of the top moving more than you could have with 14 fret anyway?

My next planned guitar is 14 fret, but after that I'll try a 12 and come up with some actual opinions rather than theoretical points.

I have read many times people touting the mid bout bridge so I assumed it was best. An example would be the Norman Blake. Some reading on that should give some thought. One reply used the banjo as an example so I will use the drum. Having been in bands in my younger years I have hit on them and hitting in the middle gives a different sound than hitting toward the edge. I think there would be a little similarity to the guitar.

On the continuum of the instrument families, while the banjo has a lot of construction in common with a drum, its sound production method is much closer to that of a guitar or a lute. If you were to strike a drum but had keep the stick pressed down on the head after you hit it, where would you hit it for max sound?

I'm not saying you flat out shouldn't try putting the bridge where you propose, I'm just recommending that you question that idea. A lot of trial and error has placed bridges off center on every stringed instrument I can think of.

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What about classical guitar? That's about as centered as you can get, between the lower cross brace and tail, and at the widest part of the lower bout.

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Somogyi has quite alot to say about this. To cut along story short he defines the "middle of the lower bout" as the middle of the area between the tailblock and the nearest transverse brace. This brace on a classical is typically "below" the soundhole resulting in a bridge nearer the tailblock. The UTB on a steel string is above the soundhole and results in a higher bridge.
I always sort of assumed the middle of the lower bout to be on a line between its widest points. Intersting FWIW

I think the reasons for placing the bridge near the center of the lower bout have more to do with the type of sound you are going for than the volume. It also depends on what style of music you want to play mostly. Volume for flatpickers is different than volume for fingerstyle players. Flatpickers want headroom so a larger box and a little thicker top is helpful. Fingerstyle players want more volume with less effort and that usually means a thinner top and lighter bracing, a guitar that could not be driven by a flatpicker without losing focus. The more central bridge yields a sweeter sound and a bridge closer to the soundhole yields a more powerful sound in my guitars.

I'm curious what 00 specs you are talking about that put the bridge where you want it. Pictures and scale length would be helpful.

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Ken Franklin
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It would take be a while to take a pic and figure out how to post it but it looks like a '28 Nick Lucas/L1 as far as body shape. The specs are larger though. The width is 14 1/4, the thickness 4 1/4 and a 14 fret neck. My thought is to increase the body width even more to 15 1/8 but keep the
4 1/4 depth. I am planning on a scale of aprox 25". That will pull the bridge toward the sound hole which will make it look like an sj 200 but of course smaller. ?
I understand the difference between a dread and a 00. If I do make it bigger it will have 000 specs. So for a guitar of that size given what you might expect for construction will moving the bridge up loose what I gain by a larger top or will a larger top give me more of what I like on this guitar? It is not as simple as comparing a Martin 00 and 000 because both of those have high bridges.

A short scale with medium strings will give you more power. A longer scale length like 25.4 with light strings will give me more power too. A 13 fret like the Santa Cruz H model is a nice compromise. Larger guitars aren't always louder, so the increased lower bout may not give you what you are looking for. The top thickness and bracing are just as important for volume as the overall size. If you are talking about a rounded bottom NL shape then making it bigger probably won't help with volume for fingerstyle play unless you get the bracing and top tickness just right. It might be alright for flatpicking volume. Moving the bridge changes the type of sound more than the volume of the sound in my guitars.

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Ken Franklin
clumsy yet persistent
https://www.kenfranklinukulele.com