GrooveTransformer Eurorack

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If you are interested in trying out the module, there is a software version of it available here

Permission is hereby granted, free of charge, to any person obtaining a copy of this hardware design and associated documentation files (the “Design”), to deal in the Design without restriction, including without limitation the rights to use, copy, modify, merge, publish, and distribute copies of the Design, subject to the following conditions:

THE DESIGN MAY NOT BE USED FOR COMMERCIAL PURPOSES.

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Design.

To cite this work, please use the following BibTeX entries:

@inproceedings{Haki2024GrooveTransformer,
  author = {Evans, Nicholas and Haki, Behzad and Jorda, Sergi},
  booktitle = {Proceedings of the International Conference on New Interfaces for Musical Expression (NIME) 2024},
  year = {2024},
  month = sep,
  publisher = {NIME},
  title = {GrooveTransformer: A Generative Drum Sequencer Eurorack Module},
}

@phdthesis{Haki2025DesignDevelopmentDeployment,
    author = {Haki, Behzad},
    title = {Design, development, and deployment of real-time drum accompaniment systems},
    school = {Universitat Pompeu Fabra},
  year={2025},
}

You can reach any of the authors if you have any inquiries or questions about the project.

Overview
Demo

Source Code
PCB
Faceplate
- Design
- Different Finishes
Interface Controls and Parameters

Source Code

PCB

`Schematics`

Download File: Front PCB

Download File: Bottom PCB

`Gerber Files`

Download File

`JLCPCB Production Files`

Download File

`Images`

BackPCP 1 BackPCP 2

FrontPCP 1 FrontPCP 2

Faceplate

`Design`

Panel Design

`Different Finishes`

No Faceplate:

NoFaceplate

Laser Cut and Laser Etched Wood:

Wood

Glass:

Glass

Glass with Printed Sticker:

Sticker

Interface Controls and Parameters

	Figure Index	Name	Description
Utility Parameters	1	Internal Clock Tempo Knob	Sets the internal clock tempo
	2	Internal Clock CV Output	CV clock output
	3	External Clock CV Input	Input for external CV clock source
	4	Metronome Click Output	Metronome click audio output
	5	Play/Stop Switch	Starts and stops the outputs and input groove record buffer
	6	Record/Overdub/Off Switch	Three-way switch to change the mode of the input groove record buffer
	7	Clear Button	Clears the input groove record buffer
	8	Shift Button	Enables secondary functions of other buttons
CV/MIDI Pattern Generation Output	9	CV Gate Voice Output	MIDI output and CV gate and velocity output for each voice
	10	CV Velocity Voice Output
	11	MIDI Output
Input Groove Control	12	Input Groove CV Gate Input	MIDI input and CV gate and velocity input for input groove
	13	Input Groove CV Velocity Input
	14	Input Groove MIDI Input
	15	Input Groove Velocity Knob	Quantizes the input groove to the grid and quantizes the velocity of each note
	16	Input Groove Offset Knob
Generation Control	17	Uncertainty Knob	Sets the value of the Uncertainty parameter
	18	Uncertainty CV Input	CV input for the Uncertainty parameter
	19	Voice Density Knob	Controls the number of hits in each sequence by adjusting the threshold of the model
	20	Voice Velocity Scale Knob	Scales the velocity output. At minimum value, no scaling is applied to the outputs. At maximum value, all velocities are scaled to the maximum value.
Latent Space Interpolation	21	Preset Selection Knob	Selects the preset number to be loaded or to be saved to. A preset consists of the saved states in the latent space Z_A and Z_B
	22	Preset Save/Load Button	Saves current states Z_A and Z_B to the selected preset number. Pressing with shift button loads the preset at the selected preset number
	23	Save/Randomize A and B Button	Sets the current state to be Z_A or Z_B in the latent space. Pressing with shift button generates a random placement for Z_A or Z_B in the latent space
	24	A/B Interpolation Slider	Interpolation position ( \alpha ) between states Z_A and Z_B in the latent space
	25	A/B Interpolation CV Input	CV input to automate the interpolation position ( \alpha ) in the latent space
	26	Follow Knob	Sets the value of the Follow parameter ( \beta ) in the latent space
	27	Follow CV Input	CV input to automate the Follow parameter ( \beta )

Eurorack Jams

Setup:

For the GrooveTransformer’s input groove, it receives a multiple of the Intellijel Metropolix gate and pitch sequence that controls the Acid Technology Chainsaw voice in the Eurorack. In this scenario, we have opted to use the pitch values of each note event to represent the velocity of the input. The pitch and gate voltages are sent from the Eurorack to the GrooveTransformer via an Expert Sleepers ES-9 DC-coupled audio interface and a Cardinal CV to MIDI converter plug-in. Generated drum patterns from the GrooveTransformer are converted to Control Voltage (CV) and sent to the Eurorack via a PolyEnd Poly2 MIDI to CV converter.

Drum Synthesis:

We use 7 voices of the generated patterns (kick, snare, open and closed hi-hat, and lo/mid/hi tom) to trigger 4 voices in the Eurorack:
Kick: Schlappi Engineering Angle Grinder + Make Noise Moddemix VCA + Intellijel Quadrax envelope generator Snare: Intellijel Plonk Open and Closed Hi-Hats: Basimilus Iteritas Alter Lo, Mid, Hi Toms: Akemie’s Taiko

To retain generated dynamics, the kick, hi-hats, and toms are routed to individual channels on a Mutable Instruments Veils. The level of each channel is controlled with the velocity sequence associated with the corresponding voice The Intellijel Plonk has a dedicated velocity input that we utilized rather than routing the signal to Veils

Video 1

Video 2

Video 3

Video 4

Module Videos (Exploring Synthesis)

Hardware 1

Hardware 2

GrooveTransformer Eurorack

Source Code

`Daisy Seed Source (C++)`

`Libre (or RPi) Code (Python)`

`Additional Info`