Overview

The lx-euclid is the result of a collaboration between Lucas Bonvin and ATOV. It is a 4 channel trigger sequencer based around Euclidean rhythms with a great focus on playability and fast editing. This was achieved by utilising an unusual interface based on two touch rings and a circular display, allowing for both fast editing as well as performance controls (Mute, Fill, Resets, etc.).

Along with normal rhythms the lx-euclid can also generate bursts of triggers. When a burst is triggered, the current rhythm plays at a multiplied clock rate. The burst continues until both the multiplied rhythm and the original rhythm align on the same step.

The lx-euclid features 4 assignable CV inputs for external modulation, as well as a probability setting for each channel giving more variations. The input range is -5V to +5V.

The lx-euclid has 8 preset slots to save and recall your rhythms.

The lx-euclid was also a ground of study for what more could be done using Euclidean algorithms, leading to the exploration of modified distribution algorithms:

• Linear Euclidean
• Exponential Euclidean — The beats will tend to accumulate around the beginning of the rhythm
• Inverse Exponential — The beats will tend to accumulate around the end of the rhythm
• Mirrored Exponential — Half the rhythm is Exponential Euclidean, the other half is Inverse Exponential

The voltage of the gate outputs goes from 0 to 10V, and the gate length is adjustable and randomizable.

The module automatically saves the current state and will recall it the next time you power on your system.

Powering the lx-euclid

The lx-euclid is powered using a Eurorack power supply and runs on +/-12V. The power connector is shrouded, and the power lines are diode-protected.

Connect the provided 10 to 16-pin ribbon power cable from your Eurorack bus board to the module. If you are not using the provided cable, always make sure that the -12V aligns with the red line on the cable.

Here is a 30 minute video about how to plug your Eurorack module correctly.

The lx-euclid consumes 120mA at +12V and 7mA at -12V.

Important! While booting, the lx-euclid performs a calibration routine of its touch sensor. It is therefore important not to touch the rings when powering up the unit.

Interface

1 & 2 - Inner ring & Outer ring

The rings can be tapped and scrolled. Remember using the original iPod? You will feel right at home! If not, try touching the surface and moving your finger around the circle.

3 - Tap button

When the module clock source is set to internal, this button allows you to set the tempo by tapping. It can also be used to manually reset all channels — press and hold the button and on release the rhythms will all reset. When preset recall mode is set to internal reset, this action also recalls the currently armed preset.

4 - Channel selection buttons

These buttons allow entering the channel edit page. From left to right these buttons allow editing channel 1 (Yellow), 2 (Red), 3 (Blue) and 4 (Turquoise) respectively.

5 - Config button

Pressing this button allows you to either enter the channel configuration page while editing a channel, or the configuration options of the module itself while on the main page.

Since Firmware V1.14.1, a long press on the config button takes you straight to the preset page.

A - Reset input jack

When a rising edge is detected on this input, all rhythms will reset and the next step to be played will be the first step.

Note: For internal resets, you can use one of the channels of the lx-euclid — for example connecting channel 4 into the reset input. In this case you should play with the offset setting of the resetting channel. If there is a trigger on the first step of the resetting channel, the lx-euclid will be stuck to its first step.

B - CV input jacks

These inputs are the CV controls of the module. They can be freely assigned to parameters of a channel (Reset, Length, Beats, Rotation, Probability, Fill and Mute). One CV input can be assigned to multiple parameters across multiple channels.

C - Clock input

When the module clock source is set to external, every time a rising edge is detected the channels move one step in their sequence. Internal clock dividers can be configured for each channel.

D - Gate outputs

These are the gate outputs of each channel. They are at 0V when inactive and 10V when active. The length of the gate can be configured in the channel config page. The LED above each jack indicates the state of the output.

Edit a rhythm

After the booting routine, you will be presented with the main display showing a graphical representation of the 4 rhythms.

To edit a rhythm, press one of the 4 channel buttons. This will bring you to its edit page. You can now use the rings to set the rhythm parameters. The outer ring sets the length of the rhythm, and the inner ring sets the number of beats.

Pressing the button again leads to a second page where you can set the probability with the outer ring and the offset with the inner ring.

Pressing the button a third time exits the rhythm edit pages and returns to the main page. At any time, pressing the tap button also exits the rhythm edit page.

Channel edit config

Pressing the config button while in the rhythm edit pages leads you to additional parameters for the channel. With the inner ring, you can select which parameter you would like to affect.

All channel and rhythm parameters are saved in the module memory and will persist after a power cycle.

At any time, pressing another channel button lets you configure that channel. Pressing the button of the channel you are currently working on takes you back to its rhythm edit mode. Pressing the config button returns you to the previous configuration page.

CVs

Here you can assign how input CV affects this channel. Select a destination using the inner ring, then in a second page choose a CV source.

• Reset
• Length
• Beats
• Rotation
• Probability
• Fill — If the voltage at the input is higher than 1V, the channel is in fill state (beat ON every step)
• Mute — If the voltage at the input is higher than 1V, the channel is in mute state (no triggers come out of this channel)
• Burst (Introduced in Firmware V1.16.0) — If the voltage at the input is higher than 1V, burst will be triggered. The rhythm will remain in burst mode until the CV goes under 1V.

You can also reset the assigned CV by pressing Clear CV.

Algorithms

• Linear Euclidean — Standard Euclidean rhythm algorithm
• Exponential Euclidean — The beats will tend to accumulate at the beginning of the rhythm
• Inverse Exponential — The beats will tend to accumulate at the end of the rhythm
• Symmetric Euclidean — Half the rhythm is Exponential Euclidean, the other half is Inverse Exponential

Clock divider

Here you can apply a subdivision of the clock to this channel. The divider options are: 1 (no division), /2, /3, /4, /6, /8, /16.

Note: The module moves one step per clock pulse. However, many clock signals run at higher resolution — for example, the ALM Pam's Workout and OXI One use 24ppqn clocks by default, which you will need to divide by 6 to get to a standard 16th note triggering.

Gate time

This allows you to set the length of the gate in milliseconds emitted at the output of this channel for each trigger. You can also choose to randomize the gate time, using the set value as the maximum.

Burst Div

Introduced in Firmware V1.16.0. Here you can set the speed at which bursts run. The available multiplications are: 2, 3, 4, 6, 8.

Config menu

While on the main page, pressing the config button leads you to the config menu. All configuration parameters are saved in the module memory and will persist after a power cycle.

Presets

This is where you can load and save your rhythms. When you enter the preset menu, you can choose one of the 8 preset slots to load a rhythm. To save a preset, press the Config button again, then use the inner ring to select the slot where you'd like to save the current rhythm.

Since firmware V1.14.1, pressing the config button a third time takes you to the preset recall modes:

• Direct with reset — The preset is recalled immediately upon touching the ring. Internal counters are reset and all rhythms start from their first step.
• Direct without reset — The preset is recalled immediately upon touching the ring. Internal counters are not reset and rhythms remain in their current positions.
• On external reset — Touching the ring arms the preset for recall. It is recalled when the lx-euclid receives a reset pulse through the reset input.
• On internal reset — Touching the ring arms the preset for recall. It is recalled upon triggering an internal reset by pressing and holding the Tap button.

The following parameters are stored in each preset: Length, Beat, Rotation, Probability, Clock divider, Gate time, Gate time randomization, Algorithm.

All other settings are saved as a global state, recalled on boot.

Macro

Here you can edit the function of the rings when on the main page. First, select whether you would like to assign a macro to the Inner Ring or Outer Ring. Then assign the function and select the channel(s) you want to affect.

Available functions: None, Reset, Length, Beats, Rotation, Probability, Fill, Mute.

Special cases — Reset, Fill, Mute and Burst work differently. To trigger them, touch the ring in a specific location corresponding to the channel:

• Up (Ch1)
• Right (Ch2)
• Down (Ch3)
• Left (Ch4)

For Burst, it will be triggered as many times as you touched the ring.

More

In this section you can modify internal parameters of your lx-euclid: clock source and touch sensitivity.

Clock source

• Internal — Use the tap button to set the tempo. Since V1.14.1, you can set the tempo in BPM — the inner ring gives fine control and the outer ring gives coarse control.
• External — The tempo is driven by the clock input. At each pulse, the clock advances by 1 step.

Touch sensitivity

Set the sensitivity of the rings to suit your liking: High, Mid or Low.

Firmware update

Start by checking the firmware version of your unit. The firmware version is shown on the display at start-up.

The current version is V1.16.0

Procedure:

1. Download the latest firmware on the GitHub project page.
   • Latest: stable and official release
   • Pre-release: unstable, in development, contains upcoming features
2. Turn off your Eurorack system and disconnect the lx-euclid from your system.
3. Connect the lx-euclid to a computer using a USB-C cable.
4. Press and hold the USB BOOT button, tap the RST button and release USB BOOT. Both buttons are located on the edge of the PCB.
5. The lx-euclid will appear as a storage device named RPI-RP2.
6. Drag and drop the firmware file into this storage device.
7. The unit will automatically restart — check the version number on the display.
8. Reinstall the module in your system.

Patch ideas

Sequence your sequencer!

To create progression with an algorithmic sequencer, you can control it using a slower sequencer. Here are a few methods:

One approach is to use a channel from the lx-euclid to sequence another. For example, connect the output of CH1 to CV1 (with an attenuator between them for finer control) and set CV1 to control the beat count of CH2. Add a clock divider to CH1 and extend the gate length so adjacent gates merge.

Another method is to use a clock divider and a mixer with attenuverters, like the MMx2. Connect time divisions to the mixer and route the output to a CV input. Matrix mixers like the MMx2 are ideal for modulating multiple CVs and parameters simultaneously.

You can also connect a CV sequencer to a CV input, driven by a clock divider. Use one channel of the lx-euclid with a single-beat rhythm to act as a divider, or use the internal clock divider for slower divisions. Smaller step counts (4–8) work well, but experimentation is key.

For a more unpredictable approach, replace the CV sequencer with a looping random sequencer like a Turing machine, driven by a divided clock. This setup is perfect for live performances where the Turing machine generates fresh progressions as a creative partner.

Independent Gate/Pitch Sequencing

One of the great advantages of multichannel trigger sequencers is the ability to sequence pitch and gate of a voice independently. Connect one channel to the gate input of a synth voice to trigger envelopes, open the VCA, and control dynamics. Then use another channel to clock the sequencer controlling the pitch, allowing for flexible and independent control over both elements.

Locking your Euclidean Rhythms

Euclidean rhythms, with their polymetric nature, create complex and pleasing phase shifts. However, this phasing may not always align perfectly with a track's structure. A simple solution is to use a clock divider to reset the lx-euclid at the start of each phrase, giving your rhythm a defined starting point and making it more cohesive.