Acoustic Guitar Construction

Just downloaded plans from Georgia Luthier Supply: Grand Symphony 12-String Guitar Plans, and aim to start this when I've completed the D28.
Currently thinking about materials and which way to go - bright or mellow, I've alpine spruce and western red cedar I can use for tops, Indian Rosewood and flame maple back/side sets but also thing about possibly using a mahogany for the back/sides but think with the western red cedar that would be too mellow...
There are some other nice woods around but trying to keep costs down if possible by using whats available in the wood store.

Other details like cutaway size/shape (if I use one) carbon fibre neck stiffeners/truss rods etc., etc will be detailed before the build begins. For now I need to sort out what body timber combinations will produce the bright/mellow options...

That I hope is where you good people might help!

Francis

Sounds like a fun project. Leo Kottke played (plays?) that Taylor 12 string which is a mahogany/sitka spruce combination which works pretty well.

I would not use Cedar on a 12 string -- making the top thicker and braces beefier is not enough, Iv'e seen bad things happen even on six string Cedar topped guitars strung with mediums for a couple of years. $.02

Francis: I agree with Ken. There is a special structural issue when making a 12-string, as I am sure you realize. Some time ago I built a 12-string and a 6-string (14 fret necks both) the same year with the same materials, except for the top. The 6 used Cedar and the 12 Sitka. Eventually I had to replace the bridge on the 6 because the Cedar began to give way just beneath the glue line. The 12, on the other hand, has survived with light gauge steel strings ever since.

Sitka is the only spruce used - I think - for aircraft props and ship's masts because it is resilient, that is, can bend without breaking. That seems to be how it has worked in my 12-string. I have not used alpine. Cedar has never been used for props or masts.

Dave, Ken, John,
Many thanks for the comments especially as they have a personal use basis. That I think puts WR cedar firmly back on the wood store shelf!
Its very early days on this project so expect more questions over time on this.
Thanks again
Francis

Well best laid plans about keeping costs down - just ordered back and side sets of Amazaque/Ovangkol and decided to make a matched pair of 12 and 6 string guitars (madness). Ordered other stuff too like fret boards etc. Already have the spruce sound boards.

I like the look of Ovangkol -- however it can be pretty stinky, I sold a knock around Yamaha Classical because the odor from the Ovangkol was unpleasant.