Quote:
Originally Posted by Craig Regan
I have noticed different arching profiles on string bass tops. Some rise up in hight quickly then flatten out across the f holes. Others are more dome shaped, cresting at the middle of the top. How does this effect the sound?
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Yes Craig it does. One of the greatest, if not THE greatest violinmaker thought so. Guarneri del Gesu altered his arching over time. Of course this is violin but it is directly related. While he kept other things surprisingly similar. He was getting more power and the later violins are more desirable by players.
The arching is the voice of the instrument. Along with other factors such as wood and how stiff it is across and along the grain, plate thickness, ff hole placement, bass bar placement, varnish etc...
You won't know how the cross arching will effect your sound until you make similar instruments and just change one thing.
Intuitively you can try for a stiffer or less stiff arching for whatever reason you have, such as if your wood seems to be floppy across the grain, it could be made stiffer in that direction by arching a more dome shape rather than a flatter slope. But it is hard to determine the cross grain stiffness in a wedge or thick plank. With thin guitar top wood this is easy just by flexing. Make a guess and hope you are right, if not you can then alter stiffness by leaving it a little thicker. Ideally, theoretically you want the top as thin and light as possible yet not too thin to promote cracking. And for similar wood (identical) a more domed shape will be stiffer at the same thickness.
All that said, it is more practical and advisable to look at the arching of good sounding basses, pick one and follow it.
I am posting this now and will add another thought later about a pinched arching.