MODIFYING AN ARRAY OF CELLS IN A CELL MATRIX FOR A STEP-SEQUENCER

A method of operating a UI for controlling a virtual musical instrument can include receiving a first input corresponding to a selection of an array of cells within a cell matrix, each array of the cell matrix assigned to audio sample data stored in a computer-readable medium that, when triggered, causes the audio sample data to output corresponding audio, and each cell within its particular array of the cell matrix, in response to being selected for playback and upon being triggered to begin playback, causes the audio sample data corresponding to the cell's particular array to be played. The method can further include receiving a second input corresponding to a changing of a number of cells within the particular selected array; and changing the number of cells within the selected array based on the second input and maintaining a number of cells in other arrays within the cell matrix.