Logic Pro X - Effects Sends: Post Pan, Post Fader, Pre Fader, Sends on Faders, Independent Pan
If you don’t already know, effects SENDS are typically used to route signal off of channel over to an auxiliary channel, or aux track as I call them. This is different than routing an output to an aux because sends split the signal. So if you just send signal over to an aux without adding any effects to the aux, you’ve effectively just doubled the signal. The most common use of effects sends is for time-based effects, like reverb, delay, chorus, and other modulation effects as well.
There are three types of sends: post pan, post fader, and pre fader. These can be a bit confusing because you might think that the pan knob comes before the volume fader, just because of it’s position on the channel visually. The opposite is actually true. The pan knob comes AFTER the volume fader from a signal flow perspective.
Note that post pan sends have green level knobs to the right of the send tab, post fader sends have blue level knobs to the right of the send tab, and pre fader sends have blue level knobs to the left of the send tab.
The signal flow of Logic’s channel strips is as follows:
Input > Audio FX > Volume Fader > Pan > Output
With a post pan send, the send comes after the pan and the volume fader:
Input > Audio FX > Volume Fader > Pan > (Post Pan Send) Output
Post pan sends will affect the volume and pan of the signal going to the aux track. So I typically use post pan sends when I want the time-based effects to follow the panning of the dry channel, like when I double guitars and I have left and right guitar parts.
With a post fader send, the send comes after the fader, but before the pan knob:
Input > Audio FX > Volume Fader > (Post Fader Send) Pan > Output
Post fader sends will affect the volume, but not pan adjusts of the signal going to the aux track. So I typically reserve these for when I want to pan a dry channel, but I want the time-based effect to stay center panned. If you use post pan for hard panned tracks, this can make the time-based effect on the aux track sound askew far left or right.
With a pre fader send, the send comes before both the fader and the pan knob:
Input > Audio FX > (Pre Fader Send) Volume Fader > Pan > Output
Pre fader sends come before the volume fader and the pan, so any changes you make on the dry channel will not affect the aux channel in any way. This allows you to independently blend the wet and dry signals.
Two new options were added in Logic 10.4.2 — Sends on Faders and Independent Pan. Sends on Faders allows you to control the send amount on the faders, rather than the tiny little send amount. Independent Pan adds a new yellow pan knob and allows you to independently control the pan of the send. Keep in mind, when you use these options, you are temporarily disabling the the channel volume and pan. Turn off Sends on Faders to go back to level mixing.