Mix N’ Match – LED Art Installation

Mix N’ Match – LED Art Installation

In October 2015, Cory Cope from Flyspace Productions called Ben up and asked him to come down to Market Square in downtown Pittsburgh to help diagnose some problems they were having with an LED mockup. That initial conversation turned into us providing design and technical services for a 32,000 square foot public art installation that included over 6000 individually controllable LEDs, an integrated audio playback unit, and a system to monitor the installation for the 6 weeks it was open. Working closely with Flyspace, artist Allard Van Hoorn, the Pittsburgh Downtown Partnership, and the Office of Public Art, we helped to turn Market Square into a giant spinning record player, complete with an urban soundtrack composed for the project by Van Hoorn.

Audio Playback

Working on the audio playback unit inside the pin
Working on the audio playback unit inside the pin

The first component of the project was the audio playback unit, which allowed guests to select and queue songs. The songs from the queue were played through both on-board speakers and headphone jacks, and when the queue was empty, the controller randomly selected songs to play. One of the challenges with this unit was that the system was enclosed in a giant aluminum pin that was mounted in the center of Market Square. Being outdoors and unattended, we wanted to maximize the audio experience, but also maximize the ability of the system to survive both the turbulent March and April weather and the locals (who are frequently not the most sober of art enthusiasts).

For playback we used surface transducers, which are similar to the driver parts of speakers, but with rigid surfaces instead of paper (or plastic) cones. These were bolted directly onto the pin structure, transforming the whole pin into a huge speaker. They were rugged and performed well, with a decent sound quality – the only problem was that they really didn’t transmit bass frequencies at all. After some discussion with the rest of the team, it was decided that the quality was acceptable for the audio being broadcast into the Square; the water-proof headphone jacks were fed from a high quality headphone amp, so listeners could still hear the high quality audio by attaching their headphones there.

LED Spiral Control & Power

View of the pin and record player from inside Market Square
View of the pin and record player from inside Market Square

The second component was the controller for the 215m spiral, which contained over 6000 individually controllable LEDs. This controller played an animation loop on those pixels, creating the spinning disk of the record. Programming the animation took some time, but the real challenge was getting power to the spiral itself: pulling 65A of power at 5V, it required #6 wires to distribute the 5 volts without excessive voltage drop. Because the entire system sat on the Square where people could walk over it, we couldn’t add power supplies anywhere but at the ends. After considering several different options, we came up with a design to feed the entire system from a single power supply located in the pin.

Tone Arm Control

The third component of the control system ran the tone arm, which was a 3-step animated display made up of 12V LED strips that were not addressable. For this, we created a 3-channel DC dimmer capable of handling the 20A per channel that the tone arms drew.

The three controllers were networked together with Ethernet cable, but we also wanted to include wireless access, so the system could be controlled remotely. We weren’t able to get wireless signals out of the pin, since it was solid aluminum, so the tone arm controller (located in a control box adjacent to the end of the tone arms) had both a GSM interface and a WiFi card. The GSM interface put the whole system on the internet, letting us use our Horatio system to monitor what was happening in real-time, while the WiFi card allowed wireless access to the control system while in Market Square (or the Primanti Bros. across the street – one of Ben’s favorite programming locations).

Monitoring and Maintenance

Mix N' Match real-time interaction data
Mix N’ Match real-time interaction data

Using Horatio to monitor the installation created a robust and maintainable architecture that gave us peace of mind that the system was running as it should. Output currents and power supply voltages were continuously monitored, alerting the production team within minutes via text and/or email if there was a variance (potentially indicating broken power supply wiring, failing hardware, or another system issue).

Additionally, this monitoring system gave us real-time access to analytics data about guest engagement: we were able to watch as the varying weather and promoted events changed the level of engagement. While Market Square is a public space that sees a lot of activity, it is also completely outdoors. When it was cold or wet, there were fewer people around, and there was less interaction on the piece; when it was warm and clear, the interaction went through the roof as people spent time in the Square. Horatio allowed us to provide Pittsburgh Downtown Partnership and the Market Square Public Art Project with useful data as to how accessible the interactive elements of the piece were and how they were being used.

Links and Other Info

Mix N’ Match Press:
Tribune Review
NEXT Pittsburgh
Pittsburgh City Paper

Time lapse video with a great view of Market Square front and center: