Gliss Lets You Synthesize Music by Drawing Waveforms

Every note and chord has a unique waveform. The famous A-440 note without any other characteristics, for example, is a perfect sine wave with a frequency of 440Hz and the amplitude corresponding to volume. But real instruments impart their own characteristics upon the waveforms they generate, which is why you can easily differentiate a clean synthetic note from the same note produced by a guitar or flute. Gliss is an open source touch control synthesizer module from Bela that lets you draw your own sine waves with the touch of a finger, so you can produce complex tones that don’t sound like they came from a computer.

Gliss is a two-dimensional touch control synthesizer module, with the first dimension being the linear position of user’s finger on the capacitive touch pad and the second dimension being the pressure the user puts on the touchpad. Those two dimensions give the user the ability to draw on the two axes of a graph that represents the waveform. That makes it easy to create organic waveforms that would be difficult to produce using conventional synthesizer controls that tend to conform to a handful of preset shapes. A typical synthesizer might let you select between sine waves, sawtooth waves, or old-school square waves, but Gliss lets you drawn any wave you want.

That works thanks to a high-accuracy Infineon CAPSENSE touch sensor, which can detect finger position in submillimeter increments. There are 24 individually addressable RGB LEDs backlighting the touch pad to provide visual feedback on the drawn waveform. There is also an illuminated and configurable input button. Gliss comes with a single mono input jack and two mono output jacks, all of which can be set between -5V and 10V. All of the functionality is handled by a powerful STM32 Cortex-M4F microcontroller, which has more than enough oomph to generate complex waveforms. Gliss fits in a 4HP slot in Euroracks, so it doesn’t take up much room and can slide in right next to your other equipment.

Bela's Gliss campaign is currently up on Crowd Supply, priced at $139, along with new and updated versions of the team's Trill sensors for purchase. Orders are expected to ship May 1, 2023.