Richard Jernigan -> RE: picado technique (Dec. 19 2014 21:02:10)
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Al Carruth wrote up some relevant experiments in his "String Theory" .pdf. http://www.alcarruthluthier.com/Downloads/stringTheory.pdf Plucking the string puts a kink into it which travels along the string until it hits either the nut or the bridge saddle. We would hope the kink would just be reflected at the nut, but would impart considerable energy to the saddle/bridge/soundboard at the other end of its trip along the string. The force exerted by the kink at the saddle can be resolved into two parts. Al calls them tension and transverse. Tension means the string pulling on the bridge in the direction of the string's length. Transverse means perpedicular to tension. The transverse force can be further resolved into up-and-down, and sideways. Al's measurments show there is a lot more energy in the transverse force. The up-and-down component of the transverse component tends alternately to drive tihe soundboard down and lift it up. The sideways component tries to shear the bridge off the soundboard, while providing a little torque, since the top of the saddle is above the soundboard. How you pluck the string regulates how much force goes into each component. Pressing down puts energy into tension and up-and down. Plucking the same amount sideways puts the same energy into tension, but puts the rest into sideways. Tension is always less enrgetic than either sideways or up-and-down. Sideways puts far less energy into the soundboard than up-and-down, if the sidways and up-and-down plucks displace the string by the same amount. So according to the experiments, pushing the string toward the soundboard and releasing it is a far more efficient way of producing sound than puling sideways and releasing. Of course you never pluck exactly sideways or up-and down. If you pluck straight sideways, the string has to go down some to pop off the fingernail. If you press straight down, the string has to go a little sideways to pop off the nail. But you can try both ways slowly, and notice that for the same string displacement, up-and-down is louder. RNJ
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