MATRIXSYNTH: Percussa Considers Entering Eurorack with Super Wavetable Oscillator/Sampler & Controller

Friday, July 07, 2017

Percussa Considers Entering Eurorack with Super Wavetable Oscillator/Sampler & Controller

via Bert of Percussa:

"I'm considering creating a super wavetable oscillator / sampler eurorack module, and would like to see if anyone's interested in having one.

The module comes with a seperate 'controller' module which connects to it via a flatcable (no power necessary for the control module). The main module is called the SWO (super wavetable oscillator) while the "controller" module the SWO-R (super wavetable oscillator remote).

The main SWO module will be based on the quad-core ARM cortex A17 platform I've designed for the Percussa ENGINE synth (see

This processing platform is one of the fastest ARM platforms available for synthesis. With its 4 cores running at 1.8GHz, it achieves about 28,800 DMIPS of processing power. Common processors in Eurorack modules are the single core Cortex M4 and M7 processors, which at their highest clock frequencies of around 200MHz stay below 500 DMIPS. Less common processors in eurorack modules are the single core Cortex A8 at 1GHz, which offers around 2,000 DMIPS of processing power.

Because of the processing power it offers, this "super oscillator" will actually support running around 64 wavetable oscillators in parallel, and with sample rates up to 192kHz with 32 bit resolution. All processing is done using 32-bit floating point precision with 64-bit precision where necessary.

You will be able to chop up the samples you load to create different wavetables on the fly. The software will support scanning the wavetables in various ways with of course modulation possibilities using the CV jacks. In the mockup you can see that the encoders are mapped to coarse/fine pitch, scanning direction, position, keyboard tracking, position noise, and mod A and B which can be additional oscillator parameters depending on oscillator mode. The pushbuttons can be used to choose wavetables, step through the oscillators, change presets, etc.

The module will come with a 1600x480 pixel IPS display, full colour, and high-end AKM ADC and DAC (stereo in and 6 channel out). The display tells you what the push buttons and encoders of the SWO-R module do. The modules have no printing on the jacks, buttons or rotary encoders because all that info is shown on the screen. The screen is NOT a touchscreen.

In addition to these high resolution/sample rate DAC/ADC chips there will be 16-bit ADCs to sample CV inputs (there are 24 connectors on the front site, 18 of which will be CV or gate inputs, configurable via the software to control pitch of oscillators or the various parameters of the oscillators). The stereo high resolution input can be used for sampling or to modulate parameters of the oscillators.

The SWO-R has high resolution endless and clickless rotary encoders (bourns) and high quality MEC switches (industrial type). The encoders have aluminium knobs on them, clear anodisation.

There will also be support for storing presets, and multiple oscillator modes. This way you can store many different routings between oscillators and input and output jacks and recall them with the press of a button.

The input signals will be routable to the oscillators however you want, and the output signals from the oscillators can be routed to other oscillators internally via software or sent out via the 6 output channels.

The SWO unit is 45 HP wide. It comes with a vertical microSD slot and a 16GB professional microSD card for storing samples. The software will support loading really long wavetables (think minutes long).

The SWO-R unit is 36 HP wide. You can mount the SWO-R above the SWO or below it, to the right or left, or whatever suits your rack setup. You could even have it outside your eurorack setup if you wanted, since it draws its power from the main module (the SWO).

Both modules are 3U in height. The depth of the modules will be around 1 inch.

Software will of course be upgradeable through the microSD card.

Cost wise I'm thinking this set of modules (SWO + SWO-R) will be around $1,500.

Power wise I'm expecting the two modules to draw around 300mA together but this still has to be confirmed when prototypes are built (which is subject to enough interest from the community). This number is based on my experience with the Percussa engine.

Right now this is just a preliminary design, so all comments and questions are welcome!"

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