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EuroPi Hamlet - Sequencing Drums and Two Voices

author: Sean Bechhofer (github.com/seanbechhofer)

date: 2022-04-16

labels: sequencer, gates, triggers, drums, randomness

TB or not TB?

Hamlet is a drum and voice sequencer based on Nik Ansell's Consequencer, which is itself inspired by Grids from Mutable Instruments. It's also influenced by O_C's TB3PO. Hamlet adds two tracks of CV and gates to the Consequencer, sacrificing one drum track to do so.

The app provides two gates for drum patterns and a pair of channels giving gate/CV to drive voices. Density of notes played on the CV tracks can be adjusted.

Use outputs 1/2 for drum gates. Pairs 3/4 and 5/6 provide gate/CV for melody lines. Send a clock to the digital input to start the sequence.

Demo video: https://www.youtube.com/watch?v=bEbHBpgIl4A

Credits:

Controls

hamlet_controls

  • digital_in: Clock in

  • analog_in: Mode 1: Randomness, Mode 2: Selects gate pattern, Mode 3: Selects voice patterns

  • knob_1: Adjust sparsity

  • knob_2: Select pre-loaded gate pattern

  • button_1: Short Press: Select previous voice pattern for tracks 1 and 2. Long Press: Cycle pattern length multiplier

  • button_2: Short Press: Select next voice patterns for tracks 1 and 2. Creates a new pattern if we're at the last. Long Press: Cycle through analogue input modes

  • output_1: gate 1 e.g Kick Drum

  • output_2: gate 2 e.g Hi-Hat

  • output_3: track 1 gate

  • output_4: track 2 gate

  • output_5: track 2 randomly generated stepped CV

  • output_6: track 1 randomly generated stepped CV

Getting Started

The following sections provide instructions for creating a simple 2 drum pattern with a kick and hi-hat, then using random CV patterns to drive voices.

Basic Usage

  1. Connect a clock input to the Digital input
  2. Connect a Bass Drum to output 1, Hi-hat to output 2
  3. Start your clock - the pattern will output gates on outputs 1/2.
  4. Select different patterns manually using knob 2 (right-hand knob). The first section of the selected gate pattern for track 1 is shown visually on the screen.

Voices

  1. Connect output 3 to gate on voice 1
  2. Connect output 6 to pitch on voice 1, optionally via quantiser/attenuator.
  3. Connect output 4 to gate on voice 2
  4. Connect output 5 to pitch on voice 2, optionally via quantiser/attenuator.
  5. Gates will be output on 3/4 according to the gate pattern
  6. The gate pattern for track 1 will be shown on the screen.
  7. Knob 1 increases or decreases the sparsity of the gates sent to outputs 3 and 4. Fully CCW all notes are played, as the knob is turned CW, notes will drop out of the sequence.

Sparsity

A key feature of the two voice tracks in Hamlet is sparsity control. With this set to 0, all events in the track are present. As the level of sparsity increases, the number of gates emitted reduces. The CV output values will only change when a gate is emitted.

This is done as follows. Each track has a number of steps, each with a voltage and sparsity value: here we assume 16 as this is a common pattern length. Sparsities are allocated randomly from 1 to the length of the track. When the value selected by the left knob is greater than the sparsity value, the step is disabled, and no change to CV value is made. The figure below shows this, with values V1 up to V16 being the voltages in the pattern and the sparsity values shown in the second row. As the knob value increases, more gates are disabled. Here, VX refers to the CV value that was being emitted before the pattern started. For example, if the knob sparsity is 10 and the pattern is looping, then VX will be V16.

hamlet-sparsity

Note that every time a CV pattern is created through a right button press, that pattern will have a new random set of sparsity values. Note also that track 1 and track 2 have different gate patterns, thus different notes will drop out giving some nice interplay between the voices.

Pattern Length

CV patterns are N, 2xN or 4xN steps, where N is the length of the current drum pattern. This can be varied through a long press on Button 1, and the display will indicate 1x, 2x or 4x respectively. Patterns of length 2xN and 4xN will be made up of two or four (different) N step patterns as described above. So when sparsity is set to 15 with pattern length 4x, there will be four notes played across the 64 note sequence.

Selecting analogue input modes

Hamlet can perform 3 different actions when a control voltage input is received at the analogue input. The current running mode is shown on the bottom right of the screen (e.g. M1, M2, M3) Cycle through the modes by long-pressing and releasing button 2. The following modes are available:

  • Mode 1: Randomness
  • Mode 2: Control voltage selects the gate pattern
  • Mode 3: Control voltage selects the stepped CV pattern

Controlling a pattern using CV

  1. Select analogue mode 2.
  2. Send a control voltage into the analogue input

A fixed voltage will select a single pattern and varying voltage (e.g. an envelope or LFO) will smoothly cycle through patterns.

Adding / Removing / Updating Gate Patterns

  1. Update patterns in the code
  2. Restart the Europi module, or restart the program if using a micropython IDE/CLI

The syntax is like Consequencer, but with only two tracks.

The mapping of BD, HH is as follows:

  • BD: Output 1
  • HH: Output 2
    BD.append("1000100010001000")
    HH.append("1111111111111111")

Known bugs / Interesting features

Probably.