Audio Graffiti project was developed as part of Roland Cahen’s sound art workshop between 7 and 11 September 2009 at Computer Music and Technology department at Sibelius Academy Finland. Concept and design was developed by Matti Luhtala and myself. Workshop outcomes were published in 14 September at old railroad tunnel redefining the previously forbidden space. Idea was to make a graffitti that makes sound by itself.
The version that we came up with wasn’t actually painted, we used alumium tape in stead of real conductive paint. To connect the electronic circuit to the alumium tape we used much more expensive copper tape. Copper tape is quite awesome stuff, the magic is that the glue on the tape is also conductive which is not the case with common alumium tape. As the glue is conductive, you can just tape a circuit on a surface. So we used common alumium tape for larger surcafes and copper one to connect two alumium tape slices to each other or to circuit itself. If we would have used conductive paint, we would still have used the alumium tape to make sure the paint is well connected to the other components. This project didn’t need too many components: couple resistors and capacitors, solar panel and piezo.
The fundamental idea was to have a painting that would produce sound without any other power source than the sun. Basic idea was ripped of from Ralf Scheiber even though we didn’t use any of his concrete designs on our graffitti. Instead I designed my own circuit using some random 4 gate NAND chip that was lying around in my stach. NAND gate synths are quite easy to design. As I’m writting this half year after this project was done, I don’t anymore remember the actual diagram, but fundamental idea is to create zillion wacky feedback loops between the gates of the chip. Tuomo Tammenpaa has detailed description at his blog about NAND chips. When you understand the magic behind the chip, you can pretty much consider it as four module modular synthesizer and patch it any way you wish to. If you don’t, just follow Tuomo’s blog entry and replace power source as solar panel.
It turned out that tuning the circuit is extremely hard as everything affects anything and sun being the most important input source keeps moving in the sky! But when you get everything tuned correctly, you will have your bird chirping by almost unheardable volume under the traffic noise. Which I in a way enjoy as trying to cover noise with sound is always some kind of loudness war. Even though chirping of the graffitti is super quiet, it can be heard surprisingly far, assuming that you are quite young person. That is probably as the frequency band the chirping happens isn’t that crowded of traffic noise.
Images © 2010 Matti Luhtala / Tunnelvision