Bridge Location SS Falcate

[Deems Davis]

The book speaks to this related to X braced guitars, but not specifically Falcate bracing. I understand the point about maximizing the effectiveness of the lower bout, but I'm clueless as to how to determine where to place the bridge center of mass relative to the size and shape, scale length.... Are there any guidelines/rules for placing the bridge when contemplating a new design?
Trevor makes the comment in the book about placement being less critical due to the braces being integral to the bridgeplate.
Curious as to what folks are doing.

Thanks

Deems

[Trevor Gore]

Most of that stuff is covered in Design, Chapter 5. Once you decide on the scale length and how many frets to the body join, you aren't left with a lot of room for maneuver. That places the bridge in terms of spacial coordinates and it's then a case of chucking a body shape around it. In terms of body shapes, the major decisions are how high the waist and how high the hips. Using circles and lines to produce the body shapes tends to give a more traditional look, using B-splines tends to give a more modern look, but all shapes can be created using either technique.

[Deems Davis]

Thanks for the reference. I was thinking that if the lower bout were a circle then it would seem that the bridge would be at the center in order to maximize the effectiveness of the sound board. Since guitars traditionally have a modified hourglass shape and the T(1,1)2 is more egg shape. Most examples I see have the saddle not on a line coincident with the widest portion of the lower bout, but positioned closer to the sound hole (I assume to better utilize that portion of the soundboard.) It would seem that overlaying a body shape template after identifying scale length, saddle position etc. could be problematic. In that the body shape could leave the position of the saddle so that it does NOT optimize mobility.
Said another way, if you could accurately predict the shape and size of the T(1,1)2 you should be able to mathematically predict the point where the maximum efficiency would be obtained when exercised.
Maybe I'm full of fog in how I'm thinking about this?
Deems

[MattW]

[quote="...Most examples I see have the saddle not on a line coincident with the widest portion of the lower bout, but positioned closer to the sound hole (I assume to better utilize that portion of the soundboard.....[/quote]


This might be due to a 12 fret v 14 fret to the body design. 14 frets to body ends up with the bridge closer to the sound hole.

Imagine half the scale length (12th fret at the body/neck edge) then moving it out 2 frets to accommodate the 14 frets design. This would basically drag the bridge in the same direction resulting in the bridge being 2 frets closer to the sound hole, and "off the center" of the sound board. With the bridge not in the middle of the lower sound board bout area, the 14 frets design (possibly) doesn't drive the sound board as well as a 12 fret design. Classical guitars have stayed with the 12 fret design for acoustic efficiency, guitars designed for different purpose (dreadnoughts) have tended towards the 14 frets design.

[Deems Davis]

Thanks Matt

I get the 12 vs 14 fret thing, and how the traditional 14 fret join under optimizes the soundboard efficiency. What I'm searching for is:

a. information about how to design the body shape relative to the scale length (which pretty much dictates where the bridge/saddle will be) so that with a 12 fret join the bridge/saddle placement drives the soundboard in the most efficient manner.

or.

b. evidence that with falcate/radial bracing that overlays/integrates with the bridge plate it really doesn't make a discernible difference so long as.


Deems

[Trevor Gore]

Either way, you're requesting a level of theory that hasn't been developed and likely can't be developed. Both require the development of some objective function that can be optimised or minimised against criteria that are difficult to define in an objective way.

[Deems Davis]

Either way, you're requesting a level of theory that hasn't been developed and likely can't be developed. Both require the development of some objective function that can be optimised or minimised against criteria that are difficult to define in an objective way.

Trevor thank you for taking the time to weigh in on this. I'm certain that the further development of this as a theory is beyond my pay grade, so for now I guess we'll leave this one in the "luthier artform" catagory