The internal shape of a dayan is a cylinder? and the external is shaped as it is only to aid tuning (i.e increase tension when wood blocks are pulled down)? Or does the increasing top to bottom mass add any characteristic to the sound produced?
A cylinder is the best shape to maximise a standing wave (I think). Is it presumptuous to say that the length of the cylinder is chosen such that a standing wave is excited around the target pitch? (subjectively aiding the sound and sustain).
I guess my underlying question is whether tabla are designed using a precise science or perhaps only traditions?
The cylindrical shape of is conducive to optimizing the resonance and the direction of the sound. It would help to imagine how sound waves would behave if the shape of the tabla were to be a cube. Definitely the pattern in which the waves would hit the inner surface of the walls of the cube and bounce would decide the behavior of those waves and the resulting sounds.
Yes, you are right. The two ostensible reasons for the gradual increase in the diameter and mass at the bottome of a cylindrical 'dayan' are:
1. To allow for a progressive increase in the tesion of the head as we move the pegs towards the bottom, thus increasing the pitch.
2. The increased mass at the bottom provides for the equillibrium of the 'dyan' so that it would stay in position in spite of agressive play.
However, the cylindrical shape and the gradual increase in the diameter and mass of a 'wooden' 'dayan' does not guarantee an evn distribution of the mass. Thaat is the reason we should be careful not to go only by the sahpe. Even a perfectly shaped dayan sometimes is lacking in equillibrium. If the 'dayan' were to be made out of a metal in a mold, we would be able to achieve and even distribution of the mass.Since we rely on nature when we pick a log of wood, it is very rare that the makerds find a piece with perfect equillibrium. And the mekaers recognize those and save for the 'ustads'
Vikash, I�ve been looking at the DYI speaker progress pages on your website and I certainly believe you�d be capable of building a dayan of your own design; you have the tools, the mechanical and scientific expertise and you appear to be the penultimate craftsman. I have been toying with the idea of finding a creative substitute for lakadi�s (dayan shells) since it appears, due to environmental issues that the supply of quality sheesam and rosewood may no longer be infinite. Even if quality instrument makers weren�t forced to cut corners to compete in an expanding world market, their raw materials are dwindling. 1.If you know of supplier of premium, cured hardwood blocks in North America of the size that would be suitable for a standard dayan I would certainly like to know. I have been looking for almost a year and a half with no luck. Unless it�s done VERY slowly, large blocks tend to check, or crack even microscopically during the curing process rendering the wood�s density a moot point not to mention the difficulty of turning a checked block or without having it warp eventually. Most wood-turners in the West rely on gluing pieces together to form a large block but that would be less than ideal for an instrument whose mass and equilibrium should be unbroken and uniform. 2.Turning a block of wood for a lakadi might work on the outside, however if I�m correct in what I�ve read, the inside cavity should be made with a chisel. I can�t remember the reason why but believe it would take someone with experience to recognize the shape and size of the cavity. 3.Using composite wood such as MDF might work because of it�s compressed mass, but it�s always denser on the outside where it�s been rolled than at it�s core. 4.I know instrument makers who�ve attempted to use aluminum in their prototypes and found it was one of the worse conductor of sound waves. Brass or bronze might work but it�d be expensive and extremely heavy in the standard dimensions. 5.High-fired clay is the material I�m leaning towards and other high-tech composites such as Corian I haven�t yet tried because of it�s expense in required dimensions. I remember there was a person once who made tables on a stand that looked like snare drums but if I�m not mistaken they also required an amplified pickup. I�d be interested to hear some other suggestions or if someone could prove my observations wrong Good luck, and please keep us informed of your progress.