Question about braces

[Matthew Tucker]

Originally Posted by Ken McKay

Smoother or more even resonances are not superior to a more "reedy" or peaky, viol sounding bass, only different.

Right.

... curved to a radius, resulting in the back being dome shaped which create about a half inch of curve from end to end and side to side. Even the area above and below the break angle is curved in the dome shape. The reason is to mitigate against cracks and to create a flat back that behaves like a carved one.

... similar to my approach, and to the construction of a roundback, you are making quite a rigid shell, inhibiting "pumping" vibration very strongly. very different to the top plate with its inbuilt flexibility at the edges. It may feel like the back is vibrating, but I think this will be largely the resonance of the whole, via the ribs. The endpin material, density and weight of the bass (inertia) will affect how much vibration is felt through the back, and how much impedence there is in the shell.

But the outcome is, as usual, hard to predict!

I feel that the back, like the bridge and neck, has a filtering and reflecting effect more than an emitting effect. No proof of this though, just a feeling. The laws of conservation of energy and momentum say that for every movement there is an equal and opposite movement, and you can't create something out of nothing, so I would think that the MORE the back is a moving component, the less the top will move for any given energy input.

If the free vibration of the back is that advantageous, I'm wondering why anyone hasn't built a bass with identical top and back plates; identical materials, grads and arching?