Project Scope
Design and build a large rotary subwoofer that generates high-energy infrasonic audio for resonance trials and practical theater effects.
Project Considerations
- Thorough safety and FMEA analysis
- Minimal vibrations
- Power compatibility
- Rigid fan blades
- Constant fan velocity
Design Solution
- 30-inch blade diameter
- 3 kW AC servo motor
- 1 kW solenoid drive
- RC helicopter hub
- Wired control box
Assembled Project
- Billet motor spacer
- Rolled steel duct
- 3D-printed linkages
- Isolating feet
Project Summary
The Large Rotary Subwoofer was a passion project I completed through the Audio Engineering Society at Michigan Tech. A rotary subwoofer is a unique type of speaker that plays infrasonic frequencies at high energy levels. This technology had caught my eye on YouTube around the time that I started college, and when I found the Audio Engineering Society I decided we had to build one. With club backing I fundraised a $2,500 budget that let my team bring the project to life. The subwoofer uses an RC helicopter pitch collective to decouple motor velocity and blade pitch. The 30" blades paired with a 3kW AC servo motor and 1kW subwoofer solenoid mean that the rotary can deliver wall-flexing power to its environment. During trials it reproduced tactile effects that simulated a minor earthquake. The project was showcased at Michigan Tech's annual Design Expo, where it competed against senior design projects with a showcase video and poster presentation. In Spring 2025 a Michigan Tech Archaeology class reached out to use it for fossil resonance trials, vibrating fossils underwater with infrasonic frequencies and picking up resonances with a water microphone. With more time and budget I'd love to continue improving the frequency response by designing lower-inertia blades made from carbon fiber laminates.
Design Expo Video
Open the Design Expo poster (PDF)
