Background and Motivation

Since this project involves a bunch of digital audio stuff that some of my readers might not be familiar with, I’ll start by describing my motivation for the project and some of the background information about the protocols and hardware involved. If you’re already familiar with this stuff and just want to see the hack, jump to the next section.

I have a somewhat unusual audio setup at home. I use a DAW (digital audio workstation) software on my desktop computer as a digital mixer for all of the sound coming from it. Using JACK on Linux, I route the output of each program to a different mixer channel, so in addition to having different volume settings for each program, I can apply effects as well (such as equalization or applying a little bit of compression when watching a movie late at night, so the loud parts aren’t quite so loud.) I can then route the audio between multiple outputs, primarily my studio monitors and my headphone amplifier.

The sound card I use is an RME Digi9652. These are older PCI cards, which are now inexpensively available second-hand since newer computers have mostly PCI-e slots instead. But, the card still works on my motherboard, has great Linux support, and provides 26 inputs and 26 outputs with very low latency. Like many multichannel audio cards, all of the I/O is digital. The 9652 has three pairs of ADAT Lightpipe ports and one pair of coaxial S/PDIF connectors. In order to get analog audio in and out, it requires the use of external converters connected to the ADAT ports.

I designed these boards to be integrated into 12VDC track lighting fixtures with MR16 LED lamps in the Media Lab atrium. They are based on the Atmel XMega A4 series (originally designed for the ATxmega32A4 and that’s what’s in the atrium lighting installation, but forwards-compatible with the A4U series chips; most of my current uses for this board use the ATxmega128A4U) and the AT86RF231 radio (though the RF230 and newer variants like the RF233 should also be usable.)

The idea of starting with a digital model of a 3D object and having a physical representation in your hands a few hours later is certainly kind of magical. I remember when my department at UW got its first 3D printer (which cost about as much as a nice car and was the size of a refrigerator) I spent hours staring through its window, watching it build up objects a layer at a time. Amazingly, just a few years later, there are now several desktop-sized printers available at a fraction of the cost. With the recent availability of these “personal” 3D printers, it’s been interesting to see the resulting models that people have printed. I’ve yet to see one that doesn’t have a few chess pieces and an Eiffel Tower or two sitting next to it, showing off its capabilities.

While these intricate models are definitely cool, 3D printing isn’t just about models that look nice. To me, the real value of 3D printing is being able to print out physical models that are functional, that wouldn’t otherwise be easy to obtain. I’ve recently been working with the Form 1, which is a recent desktop-sized 3D printer capable of some pretty impressive prints. While I’ve certainly printed a few things that are just for looking at, I’ve also been using it to make functional objects. And so far, I’ve been pretty happy.