Flat top or Radiused top?

[gordon]

I know that a lot of builders these days use a radius on the guitar soundboard but some builders such as Olson, Ryan, Charis etc don't use a radiused top.

For the builders on the forum, or anyone that wants to contribute, what's the determining factor in making the decision for or against?

[Jim Bancroft]

I'm not an expert, but a radiused top will be more ridgid. less prone to belly, although it will have a belly built in.


Jim

[mathieu thomas-guy]

You can make the top thinner and lighter without compromising the strenght. I have built my few firsts flat (mostly classics tough) and found that my domed top ones are quicker to respond and louder. Maybe thats not what you are looking for, I like flat ones too, great sustain (better?), great voice, just "slower". I believe a domed top will live longer, an arch is a great structure to distribute the load of the strings on the periphery, not just dump it in front of the bridge. Less deformation of the top around the bridge too, its fixed.

Building wise its more complicated to build a domed top so I would recommend a beginner to start with a flat top for sure.

[Ron Frazier]

It is a lot easier to build them flat.

Martin guitar tops are flat.

Need I say more?

Ron

[Laurent Brondel]

Martin radiuses its tops now.
It is actually easier to build the top with a radius, as it will flatten slightly with a low RH, but not distort.
To build flat one needs to have 100% control of RH, and build on the dry side while bracing the top and closing the box, otherwise a lower RH afterward will make the top cave in.
A well built "true" flat top will dome a bit with string tension anyway.

[danove]

I now from swedish luthier Per Hallgren that a little arc is by tradition
built into his flamenco guitars to prevent damages from drying.

I guess there will also be some strengthening effect from this.

[mathieu thomas-guy]

To Danove, you are right classicals have been built that way at least since Torres (around 1850) who uses around 4-5mm, wich is a lot. The rims are still parrallel, not too complicated to build. On some of his guitars the top is as thin as 1mm!! Some of those guitars (Romeros are big fan I had read) are still in super shape and great sounding (some recordings) wich is a testimony for such a lightweight instrument. I dont think doming is as important for steel string guitars, wich is much sturdier.

[Bob Webster]

Holy cow. I didn't know Torres put that much of an arch in his tops. I did a quick calculation and that amounts to around a 12ft radius. Apparently, Torres was not consistent in how he established the dome. In some cases, the top was flat and the bridge was arched (the method that Hauser used) and in others, the reverse was the case. Either would have been relatively easy to do given the lack of bridge pad on the inside.

Building the guitar with the edges of the sides and the bottom of the fingerboard in the same plane and with a 6mm thick fingerboard, height of the string ove the arched top would be about 11mm, just right. So which came first, the chicken or the egg?

Cheers,
Bob

[Tim Mace]

My 2 cents worth is a slight radius is beneficial in at least 2 if not more ways,strength & increased cavity.but since I'm a novice I don't have the experience to say with certainty and conviction.So I will continue to use a radius til' convinced otherwise.Besides it looks cool knowing you did it on purpose. The battle of the bulge!

[gordon]

The answers are interesting. I'm sure that the radiused top is stiffer but that in and of itself shouldn't be the reason for using one. If a flat top sounds better, I'm not saying it does but if one believed that it did than a radiused top, though easier to impliment wouldn't be the best choice would it?
I ask the same question at this forum and got an amazing diversity of answers.
http://www.acousticguitarforum.com/forums/showthread.php?t=146344&a...