Pendulum Prototype Process

For my project, I am attempting to build an instrument around the mechanic of Steve Reich's Pendulum music, a microphone swinging over a speaker. In extending this idea, I've decided to create multiple pendulums which activate different tambral effects when passing one another, In order to create polyrhythms between different swinging pendulums.

To begin this process I tested sensors that could be used to sense a pendulum passing and what pairs of speakers/microphones generated desirable/consistent feedback. The results were documented as follows:
SENSORS:
-Acrylic square swinging past distance sensor

-snappy response at distances 4.5-22.75 inches

-LEDs (ultrabright green) going past photocell

-noisy response in light at distances 0-3 inches

-noisy response in dark at distances 0-5 inches

-Neodymium magnet going past hall effects sensors

-noisy data within 1 inch of sensor

FEEDBACK SYSTEMS:

-Capacitive mic through arduino in front of 8 ohm speaker

-low low low fidelity, works more like switch than mic

-sounds horrible

-Boyscout earpiece as microphone swinging past 8 ohm speaker with laptop preamp

-nuanced feedback within 4.5” of speaker

-sounds cool when frequency shifted in MAX

I concluded that the IR distance sensor was the ideal sensing mechanism for this project and that the boyscout earpiece reversed to be a microphone over the little 8 ohm speaker would be most reliable and desirable for the project.

Then I designed a structure that I could swing things from and sense their passing. The sketch looked like this:

I designed all of the parts for laser cutting a 2 pendulum (thinner) version of this structure, I printed it out and it turned out like this:

It works! The microphone on the left pendulum swings over the speaker and its passage of the other pendulum triggers a modulation of the feedback frequency, meaning that as the left block passes the origin it creates a rhythm and as it passes the other block it creates a polyrhythm. Solid!

It is already pretty fun to play but offers mainly 3 modalities:

-full on feedback from right pendulum and moving left to play the modulation rhythmically

-free swinging right phasing with freeswinging left creating a polyrhythm with a variable duty cycle

-tapping on the right cube to make drum-style rhythms while moving the left to modulate

I'm excited to add more pendulums to increase the possibility for more complex interactions to work with. 

Many design flaws (note pipe cleaner and hacked support stand) are due to mis-measuring. 

Making this prototype out of plywood found in someones yard and in the Design Lab scrap pile has helped me evaluate the way I'm supporting structure and making me realize (with some help from Professor Gurevich) that I could benefit from a second shaft connecting the stands in addition to a stand somewhere in the middle that'll support it between the pendulums. I also need a proper amplifier for my little 8 ohm speaker and a place to mount all the components.

I will post a video demo soon, the one I already recorded has piercing audio because of my cell phone microphone trying to interpret feedback noise as a human voice... pretty piercing.