A (usually) tabletop box containing knobs, sliders, pushbuttons, or other user interface controls, which generate MIDI messages when operated. Knob boxes are frequently used to control parameters of soft synths, which relieves the performer of having to use the computer's mouse for the purpose. Using a knob box is more convenient when performing live, and some performers prefer using a knob box because it seems more like a musical instrument than the computer's user interfaces do. In the past, extensive programming effort on the user's part was often required in order to make the knob box's controls generate the desired MIDI messages, but many boxes now have automap capability, which can query a compatible DAW as to the soft synth's available parameters and automatically assign them to controls. Some such knob boxes have small alphanumeric displays which indicate the names of assigned parameters for each control.

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