A control device used as an alternative to a keyboard, mainly for playing drum and percussion sounds. A drum pad is intended to be struck or tapped, with either drum sticks or the fingers. It generates a trigger signal which usually triggers an envelope generator to play a sound with a fixed envelope profile. It may also sense velocity. Most modern drum pads use a MIDI interface, and they do the triggering function by sending a note on message with the velocity if sensed, immediately followed by a note off.
Drum pads intended to be played with sticks are usually the approximate size and shape of real drums. They use some type of sensing surface with shock absorbing properties (a lesson learned after the hard-surfaced pads sold with the early version of the Simmons SDS-V caused wrist problems for some performers). The sensing surface may be divided into multiple zones which send different signals depending on where the pad is hit. They are frequently assembled into drum kits, in the same general manner as conventional drums. Drum pads intended to be played with the fingers are softer, smaller, and more sensitive such that an uncomfortable amount of force does not have to be used. They are usually grouped into rectangular arrays in a tabletop unit.
Drum pads that output MIDI data indicate different sounds to be played by using different note numbers in their note on messages. The mapping is usually arbitrary; there is no standard, and one annoyance of using drum pads is setting up the note mapping between the pads and the sound source such that each pad plays the desired sound.