Back and Top radius

[Ben-Had]

A comment in another thread got me to thinking how the different combo radii on tops and backs may effect sound, and such.

LMI has 2 combinations of sanding braces; 25 top/15 back and 30 top and 12 back. So in this combo as the top flattens the back has more curve.

I was taught to build with 25 top/12 back and feel my guitars come out sounding real nice. What combos do others use and do you use different combos for different sized guitars? Different combos to achieve a desired dome to get the "correct" bridge height?

[Randy]

Been using flat top, 15 back. Wouldn't think there would be much difference between 12and 15 curvature. How are you setting the angle for your top?

[tippie53]

radius has little to do with tone. Most on the top is for geometry
often 25 is classical 28 steel
I played with a lot of combos and settled in on the Martin stuff.

Here is the key on the top.
Get the matching neck angle. I have seen them from flat to 25 radius . It is all in how you as the builder establish the angles. The flatter the top the less string height at the bridge. This is what will change the tone , the energy transfer at the bridge it isn't the radius.

The back , really don't matter , 15 is the most common

[Ben-Had]

Been using flat top, 15 back. Wouldn't think there would be much difference between 12and 15 curvature. How are you setting the angle for your top?

I match it to the neck angle. If my neck is 88.7* then I make my neck block 91.3*. I make my bridge AFTER the neck is glued on so I get it exactly where I want it for preferred action.