I found Audrey II on Modular Grid, even though it is not a Eurorack module. That listing led me to Synthux Academy, where I found lots of information about the instrument and ordered the DIY kit.

Audrey II is a horrorscape synthesizer designed for fearless exploration of feedback.

Building the Audrey II

The DIY Kit is unusual, as is the entire instrument design. Audrey II is built on the same platform that is reused for additional electronic instruments. Full details are on the Synthux Academy site, but long story short it is a fully digital synth programmed in C++, running on a Daisy Seed. The hardware package consists of a universal Simple Designer PC board with a place for the Daisy Seed and any number of pots, jacks, switches, etc., needed for the particular instrument. Custom front and back panels were designed specifically for Audrey II.

The kit contains one Simple Designer PCB, one unsoldered Daisy Seed, front and back panels and all panel hardware. Panels are made from etched PCB material and have a lovely appearance. A very short USB cable is included for powering and programming the Daisy Seed. An enormous quantity of yellow jumper wires are supplied, much more than needed.

Assembly

The kit comes without printable assembly instructions. You watch a video. The video did not include instructions for mounting the Daisy Seed, which came as the unsoldered version.

Assorted headers were supplied. It was no stumbling block for me, but could confuse a builder with less experience. The assembly video starts out having the Daisy seed all mounted. My mounting procedure was as follows.

• Solder two female header strips, aligning with pin 1, fully to the left side.
• Insert the double male headers (after trimming to 20 pins) into the female headers.
• Place the Daisy Seed onto the male headers and solder.

When first placing the female headers, be careful to align them vertically.

The video proceeds to show inserting the pots, jacks and switch at the correct locations on the Simple Designer board. A template is supplied on github. It’s pretty clever that a pot, jack or switch can go in any location. For Audrey II the locations match to the front panel. All pots are supplied with Vcc and ground, the jacks are grounded, and the switch is also supplied with Vcc and ground. Pot wipers, jack signal pins, and switch center pin are routed to numbered holes matching up to the number position of their component. All that remains is to solder jumper wires from the components to numbered holes going to pins on the Daisy Seed.

For some reason the kit came with forty or fifty six-inch yellow jumper wires, stripped and tinned, ready to insert. You can see above that I cut these down to size. There are only 14 yellow wires, one for each panel component. (There are three power jumpers too, for which I used my own red and black wire.) The yellow jumpers are #22 gauge and just barely fit in the holes. It was tricky to strip and tin one end of these and still fit the hole. Some I did without tinning first. I can see why the demonstration just uses the whole six inch jumper, saving the builder the trouble of stripping and tinning. But it looks awful, leaving those jumpers so long.

Programming the Daisy Seed

Like all Daisy Seeds, programming is done by running an online program with the Chrome browser and uploading the firmware file as directed in the assembly video.

Final assembly is straightforward, putting two washers over each pot shaft to bring them up to the same level as the jacks before mounting the panel and securing with pot and jack nuts.

One small catch

The Daisy Seed comes with a black protective cap over some small pins on the top (seen just to the right of the USB connector in the photo above). With the mounting arrangement using the supplied parts, this little cap protrudes up higher than the panel level. Be sure to remove that cap before installing the panel, or you will end up having to remove all the pot and jack nuts to get it off.

Sounds!