de/Rastra – http://yaktronix.com/derastra
The de/Rastra oscillographic synthesizer is a real-time audio/video instrument and computer-interfacing device that allows a performer to generate visualizations intrinsic to cathode ray tube technology while simultaneously creating the acoustic analog of the displayed imagery. The de/Rastra oscillographic synthesizer is an open source project and will eventually be accompanied by tutorials on methods of CRT hacking. Related tutorials can be found at http://www.crackedraytube.com/textstutorials.htmlbut specific information regarding de/Rastra are in progress.
A microcontroller transmits sensor information from the CRT to a computer. The data is interpreted and used to control multiple sound synthesis techniques all within Max. The resulting audio signal from Max is amplified and used to drive the yoke of the CRT creating the visualizations.
Do you remember the first Max patch you ever made? What was it?
The first patch I can remember making was actually for a digital synthesis class in my undergrad studies at The School of the Art Institute of Chicago. My professor introduced us to additive synthesis by assigning us a project to create a bell instrument using Jean-Claude Risset's Bell Synthesis Algorithm. I was amazed at how such complex timbers could be created through varying combinations of basic waveforms. I remember thinking that this was the first sound I had ever "built." No sampling or presets needed, a sound that I truly made. It was quite exciting to say the least.
The project was not only a great introduction to sound synthesis techniques, but it also helped me to establish an initial knowledge base of Max/MSP by demonstrating basic objects and methods. Even as my capabilities to build more complex systems in Max grew, I have still always been drawn to the fundamental synthesis techniques such as Risset's additive approach and John Chowning's FM work. It gives me a historical perspective that I feel helps to ground my work.
How did you come up with this project idea?
de/Rastra developed out of the combination of two aspects of my work; one being my long interest in musical instrument creation and computer interfacing using micro controllers, and the other being my fascination with CRT television experimentation. I became interested in CRTs as they began piling up in the thrift stores and left in alleys around my Chicago apartment. I saw them as an accessible medium ripe for experimentation. I initially only explored external manipulation techniques, such as video transmission, which evolved into a source of material for my ongoing VGA/TV collaborative project with James Connolly, Cracked Ray Tube.
Inevitably I was drawn further into the possibilities of CRT hacking and, after much study in proper safety precautions, I began internally manipulating the devices. I first experimented with using handmade electromagnets to distort the image on screen; a process greatly influenced by Nam June Paik's Wobbulator. Soon, I became fascinated by the Lissajou shapes that could be created by converting the TV into an oscillographic device. The concept of using basic sinusoidal waveforms to generate beautifully mathematical designs appealed to me greatly and sparked my interest. My first implementation of this method was for my installation piece sine.magnet.phosphoresced, which used Max/MSP as a sound source to drive a massive hacked CRT and subwoofers in the space. I was happy with the piece but my interests have always lied in performance, so the installation naturally migrated to the stage, eventually developing into de/Rastra. I thought of no better method to present this process than having the TV itself become the central instrument by applying gestural interfaces (accelerometer, force sensing resistors) to the physical chassis.
What sorts of problems did you have to solve?
Outside of myriad typical technical complications, I spent much of my time tuning and exploring the different waveform combinations to create interesting visuals. I wanted to create a direct 1:1 relation between the audio and the visuals; so what is seen is also what is heard. The problem is that an interesting visual does not necessarily make for an interesting sound, and vice versa. A beautifully complex sound could result in nothing more than noisy visuals without a noticeable connection between them. Conversely, an incredible visual could result in an uninteresting sound.
I found that simple FM synthesis worked best for creating visualizations. This is why the piece uses mostly fundamental sound sources such as sine waves, pulse waves, and white noise because these components resulted in more recognizable associations between the sound and image. It became quite a challenge to balance out the sonic and visual elements resulting in an extended amount of time dedicated to experimentation.
If there were one person who you would want to see your project, who would it be?
I would say Ben Laposky. Laposky was an artist and mathematician who was the first to explore these Lissajou shapes in an artistic setting. In the 1950s, he used laboratory equipment, such as function generators and oscilloscopes, to design abstract electronic visuals he called "oscillons." He would photograph these oscillons and display them in galleries all over the US. I obviously gained much influence from his work and began exploring in real time what he started producing in the '50s. I always admire people working in an area where art and science intersect. His work existed somewhere between mathematics and aesthetics, which is a space I find very compelling.
At the conclusion of this project were you:
b) ready to do a new one
c) thinking of ways to expand it
d) [other, please describe]
All of the above really, but mostly “d”. What I felt most was excitement to get out and perform it! More than building my instruments, I love performing them. I do enjoy the challenges that come along with the building process, but my overall goal with anything I make is to present it. In a performance environment I get to really learn to play my instruments.
There are always so many undiscovered idiosyncrasies with any new electronic instrument, and often they are discovered by accident during a performance. This is what is so exciting about digital performance, so many unexpected things can occur that introduce someone to areas that they didn't think to explore previously.