Send-tracks or Sends are the software audio routing equivalent to the aux-sends found on multitrack sound mixing/sequencing consoles.
Contents
Background
Software packages such as Reason, Renoise[1] and Ableton Live are based around the concept of multitracked music, where the overall sound is made up from individual sounds playing on individual tracks. For example, one track could contain the drums, one track contains the vocal lead, one track contains the guitar lead and so on. During composition, individual volume can be adjusted on each track, and effects can be applied likewise, for instance allowing a composer to add reverberation to his drum track while maintaining a clean vocal track.
The need for send-tracks arises when the composer wishes to apply exactly the same adjustments to the audio of several tracks at once, for instance if the drums are not on one track, but are instead spread out across an array of tracks, and the need to equalize them all comes up.
Advantages
Send-tracks are inherently more flexible than their hardware equivalent, since any number of send-tracks can be created as needed. For more complicated effect chains, send-tracks also allow their output to be routed to other send-tracks, which again can switch their routing to other send-tracks at the user's will through automation. The complete automation solutions offered by most multitrack software provide musicians with an easier (although arguably less hands-on) approach to controlling sends and their respective effects on the audio.