Pre- vs post-fader sends
We’ve established that auxes are damn useful for both mixing and creative reasons, but you might not be aware that they come in two distinct flavours: pre- and post-fader sends. What’s the difference? Well, as the name suggests, a pre-fader send is taken from the channel’s signal path before the volume fader, whereas a post-fader send is routed from after the fader. This means that, when you’ve got your send set to pre-fader, the volume of the signal that’s sent to the aux isn’t affected by the level of the volume fader. A signal sent post-fader, however, will disappear when the fader is pulled right down.
Pre-fader sends are used in recording scenarios to create headphone mixes, as their level isn’t dependent on the position of the volume fader, meaning that adjusting or muting the channel’s volume level has no effect on the amount of signal sent to the aux. This allows you to set a rough mix up during a recording session without having to constantly adjust the aux send levels to maintain a balanced headphone mix, which is both easier for us and more comfortable for the artist.
In contrast, a post-fader send is generally used for sending signal to processing such as reverb, delay or chorus as, when the fader is pulled down to silence, the effect receives no signal at all. This also means that any onboard EQ, dynamics or plugin processing you’ve applied directly to the channel will be present on the signal that’s going to the aux send. Generally, this is more desirable in most cases, because if you’ve applied some processing to tidy up the signal going through your channel, then the processing will also apply to the signal going to your return. However, pre-fader sends do have creative uses in the studio. Next time you place reverb on a vocal or synth part, try using a pre-fader send and pulling down the dry signal’s volume to create a more spaced out, reverb-soaked sound that can work amazingly well as an edit or in a sparse breakdown section.