The Tactus: a Tangible , Rhythmic Grid Interface Using Found-Objects

This paper describes the inspiration and implementation of a tactile, tabletop synthesizer/step sequencer. The Tactus is an expandable and inexpensive musical interface for the creation of loop-based music inspired by the Bubblegum Sequencer [2]. An optical camera, coupled with a computer running Max/MSP/Jitter can turn almost any matrix-like object into a step sequencer. The empty cells in the gridded object are filled with a fitting, colored object; the placement of which is analogous to adding an instrument or switching on a box in a step sequencer grid. The color and column position of every element in the matrix are used as parameters for a synthesizer while the row position of that element corresponds to the moment within the loop that entry is sounded. The two dimensional array can be positioned anywhere within the camera's visibility. Both the translation and rotation of the physical matrix are assigned to global parameters that affect the music while preserving the color and order of the cells. A rotation of 180 degrees, for example, will not reverse the sequence, but instead change an assigned global parameter.