The Violin is an extremely sophisticated and absolutely perfect product of engineering science combined with art. This hollow wooden box with four strings attached to it can make you cry or bring you joy. Some 18th century Violins can cost millions of dollars, not only because they are rarities, but also because they can sing. The voice of the old Italian Violin is as beautiful and expressive as the voice of the top opera Soprano. And it is also unique as any human voice. No one in this world can ever recreate the sound of any Amati's Violin, even Stradivarius couldn't do that.
Let us see how the Violin is built.
A violin consists of a spruce top, maple ribs and back, maple neck, maple bridge, spruce soundpost, bass bar, usually ebony fingerboard, wooden or metal tailpiece, endpin and four strings stretched between the tailpiece and four pegs. When the bow is drawn across the string, it makes the string vibrate with particular frequency and produce the sound of particular pitch. The sound of the string alone is very weak and poor. The rest of the Violin, excluding the neck and fingerboard, serves as an amplifier and enriches the sound with timbre or "colour". If the Violin is well crafted, the timbre is rich and beautiful, if not - then it is "ugly".
All sound producing parts work in a team, and, if any of them is not fulfilling its duties completely, it has an impact on the whole team work. Even a perfectly made violin will not sound well if the bridge is made of insufficiently dense maple, or if it is not adjusted properly to the top and not sitting well. This applies to every part.
There is not much that can be done with the top plate or back, it is given. But in the whole sound making chain every link should be working properly. Then only you will be able to get the sound out of your Violin and make it sing as you want it to sing.