I was inspired after watching a video of the “Hang Drum” to make a MIDI controller based on a hemisphere. I’ve used the awesomely fun DJ TechTool’s MIDI Fighter 3D for live performance in the past and wanted to make a “hemispherical” version of this. Why a hemisphere? This way, one can fit more buttons in the same space and not have to switch pages. In terms of hand placement, the curved shape is also more ergonomic.The hemisphere is an 8” IKEA Blanda Matt salad bowl. The holes were made using a 25mm holesaw. The buttons are Sanwa OBSF-24 Arcade buttons.
The internal wiring will be hooked to an arduino which will send the data on the various button states to the serial monitor. MAX/MSP will then be used to convert the serial data from the arduino into midi messages that will be sent to Ableton Live.
The layout consists of “layers” of eight buttons and was originally conceived be used to as a “hemispherical MPC”. However, the layout also paves way for adding scales to each of the circular layers. For example, a C major diatonic scale can fit on the first “layer” of 8 buttons with each layer being an octave lower. This is similar to the approach used by the Ableton Push controller where the user can “play a scale” on the 8 x 8 array of buttons. In this case, it is a hemispherical array of 8 buttons.
I originally wanted to fit a potentiometer to the top of panel of the device for lowpass and highpass filtering, but now this pot can be used to select the scale or mode.
Each “layer could” also be tuned to provide the best layout for playing chords. For example, the first layer is a C diatonic major scale, but the layer below is “offsetted” such that the corresponding button below any note on the topmost layer is actually a perfect 5th or perfect 4th above/below the note. This would be like the tuning each layer of buttons akin to the strings of a guitar. In this case, LED feedback using clear rim arcade buttons can be used to indicate whole steps and half steps etc.