LED Sousaphone Bell

by John Baylies - sousastep.com

Many thanks to the Brooklyn College Sonic Arts program and the Performance And Interactive Media Arts program.

Click here for a compilation of short clips I recorded while I was making the bell.

If you haven’t soldered before, Nic Collins’ book Handmade Electronic Music is a great way to learn how.

Adafruit has a soldering guide specifically for LEDs.

If you are unfamiliar with Max/MSP, check out the tutorials.

Also, check out Jay Converse’s LED bell because it’s cool too.

Materials

Initial Setup

Click here for instructions on how to connect the OctoWS2811, Teensy 3.2, power supply, and LEDs. This is to make sure everything works before it’s installed on the bell.

Download this folder o’ files. If the Google Drive link ever goes down then the files are also available in this repository.

Upload success.ino to the teensy by following these instructions.

This part of the code is the most important, and may need to be changed.

const int ledsPerStrip = 26;
const int numStrips = 8;
  • Open testpatch1.maxpat

  • Turn the patch’s audio on.

  • Clear the serial ports and locate the teensy.

  • Enable jit.world, and the LEDs should light up…

Getting the Coordinates

Here’s how I got the coordinates for remappedLEDcoordinates.txt

I found this website, clicked “table”, selected the first 200 coordinates, copy-pasted them into google sheets, exported the sheet as a csv file, and used Justin G’s max patch to convert the csv file into Max’s coll object.

then,

max-scale-coords.png

This patch will get the Fib. Spiral showing up properly in jit.world

flipped-on-xaxis.png

Left, incorrect, flipped on x-axis. Right, correct. (challenge: turn the coordinates 90 degrees. It’d look more symmetrical.)

Arranging the LEDs

Take a screenshot of the spiral in jit.world (or use the one provided above), and use a projector to project it onto your sousaphone bell. This will be where you place your LEDs. I found that it is easier to place the LEDs while the projector is on than it is to mark the spots with a marker and then put the LEDs on top of the marked spots. Once completed, the bell will look best from the point of view of where the projector was while you were placing the LEDs

One problem I faced is that I placed half the LEDs, then took a break for a few days, and when I tried to set up the projector again I learned that realigning the projector perfectly is impossible. This led to one speck of light hitting the flare of the bell the first time, and the throat of the bell the second time, which made me place one extra LED, which led to much confusion later on.

You’ll want to wire the 200 LEDs in eight groups of 25. You should use your own discretion to do this as efficiently as possible. You can use my wiring diagram below as a guideline, but be warned that it’s flipped on its X axis, and I had to account for one extra LED. Fibonacci index #29 corresponds to wiring index #35 and #170.

numbered-indices.jpeg

I used this diagram to reorder the coordinates from the Fibonacci spiral order to my wiring order.

The top numbers are the Fibonacci indices, which can be obtained from here by clicking number. The bottom numbers are the wiring indices. I did not plan out the wiring indices in advance. I simply turned on the first LED in each of the eight chains and wrote down the wiring indices on the above chart.

Then I typed all of those indices into a coll object, which allowed me to reorder the coordinates properly using the patch pictured below.

coll-reorder.png

This essentially makes the whole thing a big, low-resolution TV screen.

…and that’s all the info you need to do this yourself. Best of luck!