Physics of Percussion Instruments Drum Shell Bearing Edges

Physics of Percussion Instruments Drum Shell Bearing Edges Final Talk • Eric Macaulay • Prof. Steve Errede Department of Physics University of Illinois August 8, 2003 emacaula@iwu. edu

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 45ºExperimental 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± 1 g 590± 1 g B - Single 45º w/round-over 461± 1 g 598± 1 g C - Double 45º 444± 1 g 660± 1 g

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 Macaulay emacaula@iwu. edu