Computer Musician, Programmer, Hardware Hacker

Here's the first prototype of my tabulaRasa wavetable oscillator module

Making progress on the tabulaRasa hardware – ordered the second prototypes from dorkbotpdx today. More soon.

The box the Ohm came in.

I recently found out that you can get a “graveyard” Ohm MIDI controller from Livid Instruments for $30. This is a defective unit that they couldn’t sell. They’re secretive about what’s wrong with the units, and there’s little to no documentation available, but I thought it would be fun to attempt to rebuild one.

I also ordered a Ohm64 case, which is a wooden shell for the hardware. It’s not exactly the right size, but I thought I might be able to convert it to work with the Ohm Classic.

The circuit boards of the Ohm, as I received them.

You can see in the image above that the boards are a bit old, I had to rub some corrosion off – a bit of rubbing alcohol did the trick. The “double-checked” marking  on the back of the main board was reassuring. The loose wire beneath that main board was a bit scary, but it turned out the be a ground wire which connected the three panel boards to the main controller board.

In all, I received 4 boards – three, attached to the panel, which contained the pots, sliders, and buttons. These three connected to the fourth through a set of ribbon cables and power wires.

Note that these “graveyard” Ohms do not come with the MIDI/USB I/O board. I ended up having to order one separately. Extra shipping – be careful!

Main board, wired up for testing.

My next step was to somehow power the board – without the I/O board power circuitry – and test the controls. More on that later.

I’ve made an Octomod object in PD-Extended and bundled it with a modified version of the NRCI library I co-developed a few years ago. It’s got a great set of control data and rhythm generators, which make it really easy to get some interesting patterns up and running quickly – and now sent out over OSC to the Octomod Processing app.

Here’s the PD-Object and library. (open the -workspace.pd file)

And for more info on the use of NRCI:

https://ccrma.stanford.edu/~cburns/NRCI/