In audio a submix is a grouping of instruments or tracks that are mixed or inserted into the “main” mix as a composite signal (usually as one or two inputs). Submixes are used in many different types of situations and can take many different forms. Most mixing boards have a number of subgroups that can be used to help the engineer organize different kinds of sources. Drums may be on one subgroup (sub, for short), while vocals are on another. This can make it much easier to control groups of instruments without having to make identical changes across many channels of a mix. Submixes are also handy when there aren’t enough channels or recording tracks to handle all of the sources. In those cases a separate mixer is employed to “pre-mix” a group of sources down to a one or two channel composite that can then be brought in to the recording or main mix.