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ADDAC System402 Heuristic Rhythm Generator


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The ADDAC402 Heuristic Rhythm Generator is a four-channel rhythm generator that excels at creating complex rhythmic patterns. Each of the four channels have a step and fill knob, with individual fill CV inputs as well as skip step and reset buttons. These function differently depending on what mode you have selected—but more on that shortly. There is also a play/pause trigger input, a clock input, a master reset, a swing control, and an assignable CV input. Each of the channels has a gate output and a complementary inverted gate output that mirrors the state of the gate output. The gate lengths can be set either by a switch or by knob in some of the modes. There are 16 preset slots available for saving and recalling settings.

There are seven modes in the ADDAC402. These include: gate sequencer, Euclidean, Game of Life, Golomb rulers, probabilistic, Footwork’n, and Pong. The gate sequencer is a fairly straightforward step-based gate sequencer mode. The pattern length can be set with the steps knob, and the fills knob moves the cursor. The skip button adds or deletes the selected step. In Euclidean mode, the steps knob controls pattern length and fill controls number of active steps. The steps are evenly spaced throughout the pattern length. The skip button can be used to manually advance the sequence independently of the clock speed. In gate sequencer and Euclidean modes, the individual resets and master reset both are used to reset the sequences back to the first step.

Game of Life, originally developed by John Conway in 1970, is a cellular automata-based “game” that creates complex results from simple initial states. The Game of Life mode randomly creates patterns of steps that turn on and off (steps are born or die in Conway’s terms) based on the state of the adjacent steps. Steps knob has no function and fill sets the number of bars in the grid. Individual resets will create a new initial pattern while the master reset calculates an entirely new Game of Life pattern.

With Golomb rulers mode, fills sets the number of marks in a pattern, no two steps have the same distance to each other. This works in contrast to the equal distribution of the Euclidean mode. In Probabilistic mode, the fill knob sets the chance that a gate or trigger will be output from the module. The probabilities are related to each other and adjusting one affects the others in turn.

Footwork’n mode is based on a code bug and uses the four fill knobs together to set various functions. Speed is related to the clock but kind of does its own thing. Events sets the quantity of events (it’s an event-based mode, surprise surprise), factor influences events rhythmically, and length defines the length of the momentary event. These controls may not be immediately apparent, as they affect the algorithm over time. The steps knob sets the gate length for each channel.

Pong is the classic arcade game adapted to generate gate patterns. The gate outputs are triggered when the ball hits the walls. Fills one and four move the paddles up and down, while fill two sets the speed of the game and fill three sets the size of the paddles. The fill CV inputs can be used for voltage controlled classic video games.

If these modes are confusing the Mode Info button can be pressed and the screen will display a bit of text describing the mode—so help is always within reach!

ADDAC402 Features

  • Four-channel complex gate generator
  • Seven modes from gate step sequencer to code bug
  • CV control over fill function
  • Global swing
  • Up to 16 presets
  • Complementary inverted gate outputs
  • Play/pause trigger input
  • Clear OLED screen
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  • Eurorack module
  • Width: 20hp
  • Depth: 55mm
  • Current draw: 140mA @ +12v, 40mA @ -12v
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