May 132015
 
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Jason & Company – Click to Enlarge

88 DMX-Driven RGB LED Nodes

88 DMX-Driven RGB LED Nodes, circa 2005

This was a fun project.  Earlier this spring, University of Buffalo composer and percussionist Jason Ross saw our 2010 post describing a clever way to drive new-at-the-time ‘smart’ LED pixels via MIDI input.

He wanted to do something similar as part of a senior project. He was using a trio of MalletKATs to perform an original composition and hoped to map LEDs to individual notes as they were played. These particular ‘KATs contain four full octaves each, plus an extra ‘C’ on the top end.  He required a real-time, stable, hardware-based solution and we were happy to oblige.

Musicians will appreciate that this quantity of notes exceeds even the extended 128-step MIDI scale.  So we offered some custom programming for the versatile blue DecaBox which made everything work perfectly and simultaneously.

To make the installation a success, we provided three strings of smart LEDs, a power supply / decoder with modified programming, and our standard MIDI to DMX DecaBox, also with bespoke firmware.

We assigned each MalletKAT to a separate MIDI channel, and then mapped the specific MIDI notes generated (C3 – C6 inclusive, plus high C7) to three different ranges of DMX channels.  The DecaBox was then programmed to set all three colors of a specific RGB pixel to equal levels when MIDI Note On messages were received.  The brightness of the bulb tracks the note velocity (or loudness) as it is played. Thus, dynamics can be seen as well as heard.  The pixels are extinguished under MIDI control as well.

It takes a bit of math to route all the data to its proper end position, but that was all worked out through a few hours’ testing.  Our gear can receive and process a full pipe of incoming MIDI data in real time, so the lag between the input and display LED output is only about about .025 seconds.  This was especially important since the piece was to be performed live.

Smart LED DMX Interface - Click to Enlarge

Smart LED DMX Interface – Click to Enlarge

Shown here is the system which receives DMX from the DecaBox and generates the properly mapped control signals for the three smart LED strings.  This was a quick-turnaround project, so we secured the circuitry in a generic CATV demarc box with a laser cut mounting panel.  In this photo, the top cover was removed.

And finally, here is the YouTube link for Synth-phony in Lights:

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YouTube Link – Click to Play

Nice work, Jason.  It was a pleasure to collaborate with you on this design.  Need something similar? Let us know.

 

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