Noise Engineering - Tonnetz Sequent


Tonnetz Sequent is a three-voice chord/triad generator basing on mathermatician Leonhard Euler's Tonnetz idea, expanded by a number of triad transformations and transpositions. All functions which transdorm triads can be activated by buttons and gate signals rhythmically. Output sockets carry the Root note, the Third and the Fifth plus a trigger with each triad transformation.



Euler's Tonnetz principle has to be considered a conceptual lattice diagram representing thirds and fifths and the interval relations. For that reason Tonnetz Sequent has three outputs with 1V/octave characteristic: the Root note, the Third and the Fifth.
Gate inputs of the module allow for moving within the triad space by rhythmical siglans like gates. The three inputs and gate inputs for standard transformations are:

  • P (Parallel Transformation). In major mode the third is transposed one semitone down, in minor mode one semitone up.
  • L (Leading = Tone Exchange Transformation). In major mode the root is transposed one semitone down; in minor mode the fifth output is transposed one semitone up.
  • R (Relative Transformation). Major: fifth is transposed one semitone up. Minor: root is transposed one semitown down.
Besides this there are three more buttons/gate inputs referring to the triads directly:
  • M (Mode Transformation). Selects triad pairs which are to be transformed: minor/major, major/augmented, augmented/major, major/minor, minor/diminshed, diminished/major and back to the beginning.
  • H (Home Transformation). Resets the current triad back to the root chord of the current Mode pair.
  • T (Transpose Transformation). Transposes all notes of the triad one semitone up.

The Group function offers a voltage controllable rotation of P, L and R.
The Modulo switch limits the triad's range to one octave. Notes which would fall outside of the octave will be mapped to their equivalent tone within the base octave.
Every time a transformation occurs the trigger output emits an impulse.
When pressing the Tune button all outputs generate the same constant voltage - perfect for unisono tuning of the VCOs which is necessary prior to using the module.


six transform gate inputs: P, R, L, M, H and T
group CV input, trigger output
1V/octave outputs: root, third, fifth


3U Eurorack module, 8HP wide, 35mm deep
power consumption: 50mA @ +12V and 5mA @ -12V

0.068 kg
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