During mixing, the aux sends are used to add effects to our mix. The aux sends are mainly used to send a copy of the channel's signal to an external module. So, once the signal has been sent to the module, we wish to bring back the signal that has been manipulated and use it in our mix. To do so, we need to use an extra input on our mixer called aux return. Let's imagine that we want to add a reverb effect to the lead vocal. Following our example we can use the aux send 1 of channel 10. By turning both this potentiometer and its respective aux send 1 master we'd get a copy of the lead vocal at the aux send 1 output. The latter is available on the patchbay, therefore we can connect this output to our chosen reverb unit's input (the connection to this input also is located on the patchbay). Once the signal has entered the effect we can adjust its volume (either with aux send 1 master or the effect-input gain). At this point, the effect's output is connected (still using the patchbay sockets) to the aux return 1 input (usually the returns are stereo). In the mixer's master section we find the controls for using these returns. Here we can adjust the volume (with the aux return master) and route the returns to various destinations, like the groups for example, or directly to the master output. Remember that aux returns can only readdress the signal: it doesn't have the facilities to perform any manipulations. If manipulations were necessary, we could consider the option of sending the signal back into two unused channels rather than to the aux return section. For example, we could use channels 30-31 (our reference mixer has 48 tracks) seeing that reverb supplies a stereo output to emphasize the feeling of spaciousness: on these channels we can now use all the available facilities, like equalizers and compressors. The signals on these two channels could be sent to groups 11-12, thus allowing us to control two voices with two faders (lead and harmony) and their respective reverbs (to send the harmony to reverb too, all you need to do is lift channel 11's aux send 1... easy peasy, eh?).
The mix bus output is connected to the DAT for the recording of the master. When we're satisfied with all our levels, all that remains is for us to press rewind on the multi-track recorder, record onto DAT and... enjoy the show!