physics of percussion instruments drum shell bearing edges final talk eric macaulay prof. steve...
TRANSCRIPT
Physics of Percussion InstrumentsDrum Shell Bearing Edges
Final Talk• Eric Macaulay• Prof. Steve Errede
Department of Physics
University of Illinois
August 8, 2003
Overview
• Motivation
• Methods
• Results
Motivation
• Understanding more about drums• Manufacturing better drums• Development of software
Three Bearing Edge Designs
• Single 45º -Classic Design
• Single 45º w/round over-Modern Design
• Double 45º-Experimental Design
• Better Energy Transfer
Problems with Drums
• Drums are not identical
• Different Masses• Different Shell Ply
Organization• Different Resonant
Frequencies
Drum Shell Weight
Rim Weight
A - Single 45º 491±1g 590±1g
B - Single 45º w/round-over
461±1g 598±1g
C - Double 45º 444±1g 660±1g
Recording Shell Sound
• Interested in how the shells themselves vibrate.
• Nothing attached• Lugs attached• Drum mounted on
stand
Progression of Major Shell Harmonics
Recording Drum Sounds
• 2 microphones• 1 to monitor
overall sound• 1 very close to
the shell
Record at Different Head Tensions
• Drum Dial (left) measures head tension at each lug.
• Drum Torque measures torque of each tension rod
Testing Tune-ability
Example of 2 Microphone FFT
Shell Mic/Head Mic
FFT Ratio vs. D. D. Tension
A: shell/head B: shell/head C: shell/head
A: head/shell B: head/shell C: head/shell
Head FFT with Chebyshev Filter of First Harmonic
Shell FFT with Chebyshev Filter of First Harmonic
Exponential Fit to Standard Deviation of Filtered Data
Time Constants From Curve Fits
Shell/Head Coefficient Ratios of Curve Fits
Conclusions/Acknowledgements
• The double 45 degree bearing edge appears to be better and transferring energy
• More evidence is required
• More drums• More testing
• Special thanks to Prof. Steve Errede
• Jack Boparai• Lee Holloway• Mats Selen• Nicole Drummer• Dennis at Phattie
Drums
Eric [email protected]