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How many builders here build with a flat top with no raidus in the bracing??
I know of a few companies like Olson and Laravee (sp) that do them flat.
What are the adventages and disadvantages ??

Thanks Gary

Gary, my understanding is that the dome provides added strength and provides slight play to allow the wood to move without cracking. A true flattop might make setup easier as the upper bout doesn't have to be braced flat or flattened by sanding. However, I may be wrong and usually am. I know most folks here are building with 25 tops and 15 backs. I use 28 tops and 20 backs.    

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Don Atwood
Arlington, VA

I heard it also affects the tone, but who really knows. It just makes logical sense that the top would be stiffer if domed and less chance of cracking when the wood expands do to humidity changes. But I would suspect that if you built in a controlled environment of 40 to 45 Relative humidity, then maybe this would not be an issue. I do mine as 15' and 25', but on the next it will be 15' and 28'.
Tracy

The domed top will rise and fall with changes in humidity, a flat top will be more likely to split when it shrinks due to a sudden drop in humidity.

Tracy is correct. The bigger the dome the more treble response you will get from your guitar. I have found the opposite to also be true.    I am sure that some would argue with this but this has been my experience.

More radius = higher timber and more sustain.

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tim...
http://www.mcknightguitars.com

My guitar (my first) has a 25' cylindrical radius on the bass side, 12.5; cylindrical radius on the treble side. Hard to say what effect it has, as I have no "base line" guitar to compare it to.

[QUOTE=GCote] How many builders here build with a flat top with no raidus in the bracing??
I know of a few companies like Olson and Laravee (sp) that do them flat.
What are the adventages and disadvantages ??

Thanks Gary[/QUOTE]

Just a not on Larrivee: unless they've changed their construction methods in the last 10 years (since the GAL talk that's in the Big Red Book, volume 3), Larrivees are built with a radius in the upper bout, and none in the lower, relying on string tension to 'pull' the arch into the lower bout.

[QUOTE=GCote] How many builders here build with a flat top with no raidus in the bracing??
I know of a few companies like Olson and Laravee (sp) that do them flat.
What are the adventages and disadvantages ??

Thanks Gary[/QUOTE]

Are you sure? 100% dead flat tops? This seems against all building principles for the acoustic guitar.

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Lance@LuthiersForum.com

[QUOTE=Tim McKnight] More radius = higher timber and more sustain.[/QUOTE]

Makes sense. Dome = high timber. Question though, what does it do to the timbre. Sorry Tim, I just couldn't resist

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Don Atwood
Arlington, VA

That is what I remember reading in the last few years.

I also use a 15 and 25" raidus but was just curious about no raidus on the tops. I would also think it would not be as strong. Thanks for all the input guys..

Gary

[QUOTE=Don A] [QUOTE=Tim McKnight] More radius = higher timber and more sustain.[/QUOTE]

Makes sense. Dome = high timber. Question though, what does it do to the timbre. Sorry Tim, I just couldn't resist [/QUOTE]
chhhhching ....

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tim...
http://www.mcknightguitars.com

Charlie Hoffman use a flat top with no dome or arch. Hoffmanguitars.com See step 14. for his rational.

On the occasional acoustic I build I use the Hoffman method too, and it works fine for me. It's worth mentioning, however, that we don't get such extreme humidity variations in the UK as you do in the USA, so I don't know how it would hold up under those conditions.

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Pete
http://www.petewoodmanguitars.com

I suggest you take the top splitting theory seriously.

I built my second with a flat top. Not because I wanted to but because I'm not real good at this guitar building thing. Sure enough the first winter the top split. I'm in Toronto, so we do get pretty dry winters up here. If you anchor the two sides of a thin piece of wood, then allow humidity to shrink the wood, it will split.

I have always loved this topic. Olson makes 60+ guitars a year, aguably, one of the nicest and sound wise one of the best acoustics out there. His guitars go all over the world and some of the most renowned acoustic players play his guitars.

When I was building my first, I phone Jim and asked him about this, he builds with a 100% flat top, and he drops the front of the body to account for the set of the neck.

I have a friend who has two olson's and the older one, 1992 I think has an induced dome to it due to string tension. I live in BC, Canada on the west coast and we get very wet weather compared to Minnisota where Jim lives.

So, here is a guy (Jim Olson) putting all the marbles on the table (his reputation and livlyhood) building and designing one of the worlds best guitars (arguably of course) which is traditionally inferior in design to the majority of the building community (100% flat top). When I spoke with him, he told me he has never had a guitar returned due to a spit top.

So, I built # 2 and # 3 with 100% flat tops, the jury is still out there on them as # 3 is only 3 months old, yet # 2 is 1 1/2 years old, no problems yet.

By the way, both # 2 and # 3 sound better than the first (usually happens this way though) and I do beleive that it has something to do with the design and brace placement (Jim also has a different lower brace (tone bar) brace placement that may aid in the strength for the "flatness" of the top).

Anyway, If it's working for someone as succesful as Jim Olson or Charlie Hoffman, who's to say that it is incorrect or detrimental to the design.

Take this for what it's worth, but i think they may have something. Oh, if you read on Charlies site, he changed his design years ago after he saw the way Jim did his tops.Rod True38494.6554861111

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