A pre fader send simply routes a copy of your track before the channel fader, whereas a post fader send will do this after your channel fader.
But what difference does it make?
Well in terms of mixing it is often advantageous to use a pre fader send. This is because the signal itself will essentially be independent of the channel fader, meaning you are free to raise or lower the fader without influencing the level that is being sent to the auxiliary track.
When To Use Pre Fader Over Post Fader?
Pre Fader Use Case #1: Effect Tracks
There are several reasons why pre fader sends are advantageous, one being that an auxiliary or bus
track can be used solely as an effect track (such as reverb or delay).
You might find the sweet spot on your guitar reverb but if the signal is sent post fader any tweaks made to the guitar channel fader are going to affect how the reverb sounds and you’ll be forever correcting each.
You could however simply insert a reverb plugin onto the track you want to affect, which isn’t technically wrong — but using this method you will easily eat into your computer’s resources if you have multiple plugins with effects on each.
Using an auxiliary track just for your effect means you can route multiple tracks into one effect, therefore only using one plugin for the whole process.
A great way of improving your workflow is to set up a template for your mixes, typically with three or four auxiliary tracks – two reverbs (long and short) and two delays (long and short).
This way you can easily route your tracks to these plugins but also set the level independently meaning you are free to lower and raise your channel faders without changing the effect.
Once you have set up your template, try setting the ‘dry’ setting on your reverb and delay to zero and
the ‘wet’ to full. This will mean your auxiliary track will only produce the affected sound, which you can lower and raise yourself to taste. It will also mean that you have a dry and an unaffected track which you can blend together with your channel faders.
Inserting an EQ plugin after your reverb and removing some of the lower frequencies with a high pass filter will remove some of the muddiness that reverb can cause.
The advantage of this is you can aggressively EQ the reverb if need be without affecting the original signal.
In the example below, you can see a vocal track being routed to a long reverb and long delay track. The vocals have their independent level whereas the faders on the effect tracks are set to different levels and will not be affected by any changes in the vocal fader.
The effects are set to 100% wet meaning the only thing we will hear on these tracks is the effect itself, and a high pass filter has been applied with the EQ plugin:
The level of signal being sent to the effect tracks can also be raised or lowered:
Pre Fader Use Case #2: Parallel Compression
There are of course other situations where you may want to use a pre fader send. For example, you may want to parallel compress your drums tracks.
Parallel compression is where the original track is blended with a heavily compressed track, so in this case you would want to hear all your drum microphones but route each track to a separate compression track to be heavily compressed.
By sending the signal pre fader you can ensure you are hearing both dry and wet tracks, but you might find you want more cymbals in the dry mix, and less on the auxiliary track.
A few simple tweaks and you’ve created two mixes of the drums.
Pre Fader on a Mixing Console
The idea of pre fader sends can be utilized on a mixing console as well as in the box. Like the above ideas, pre fader sends can be used to create auxiliary tracks to be compressed or sent to a piece of outboard equipment.
A pre fader send is also advantageous when creating mixes for your performer to hear in their headphones.
For example, if you are tracking drums then your drummer will usually want to hear the backing or guide track and the click track as well.
By sending both tracks to their headphones pre fader you can create a separate mix for the performer
and for you monitoring in the control room.
The drummer will need to hear the click track to ensure they are staying in time, however in the control room you will be listening to a number of things such as the mics themselves, the timing of the drummer and the overall feel.
Because you’ve sent your signal pre fader, your drummer has their own mix and you are free to raise or lower the click, the drums or guide track in the control room via the desk faders without changing what they are hearing.
When To Use Post Fader Over Pre Fader?
Post Fader Use Case #1: Bussing
If you’ve recorded a guitar-heavy track for example you can use a post fader send as a way of controlling all the guitar levels with one overall fader.
Let’s say you have double-tracked your guitars and have also recorded a lead line over the top. You’re
happy with the levels but feel that they may want to come down a touch in the chorus.
By setting the output of your guitars to an auxiliary track you are sending the signal after the channel faders and can, therefore, use the fader of the auxiliary track to raise and lower the guitars.
A bit of simple automation on the auxiliary track will allow you to lower the levels of the guitar in the chorus with one fader rather than three.
In this example the output of each track is routed to the Guitar Bus.
This means that the levels of each guitar track can be controlled by the bus track in yellow.
There is however a difference between routing your channel output to an auxiliary and using a send. A send can be set to post fader, but it will route a copy of the signal to the auxiliary meaning you will still hear your original tracks and their volume will still be independent from the auxiliary.
Below, we can see the guitar tracks are sent post fader, meaning that the bus fader in yellow will control a copy of the signal, rather than the original.
As you can see both pre and post fader have their advantages, however using a pre fader send gives you an extra level of depth when it comes to mixing effects and can create some really interesting sounds which often will add another dimension to your mix.
That’s not to say that post fader sends aren’t useful as they can be great as a way of controlling the
levels of a group of instruments which would be time consuming otherwise.
Try experimenting with both and see what results you get!