Master faders can come in two varieties, Pre-fader or Post-fader. This indicates where in the signal chain the insert effects are in relation to the master fader output. Let’s dive in to learn more about the two types, and why one might want to use one over the other.
“Pre-fader” means the sound coming into the master fader will go through the effect inserts of the master channel strip before flowing out to the master fader itself. Since the inserts come before the fader in the signal chain, adjusting the master fader itself merely adjusts the overall volume of the sound after it’s been processed by any insert effects. The sound will remain unchanged when moving the master fader, it just goes up or down in volume.
“Post-fader” means the sound coming into the master channel will go to the fader first before it’s sent to the effect inserts of the master channel strip. This means you can use the master fader itself as a trim control, allowing you to control the amount of signal being fed to your master effects chain. Changing the amount of signal can change the way processors react to the signal, so it’s important to understand this and find your sweet spot if your master fader is Post-Fader.
Pro Tools works in a Post-Fader fashion while other DAW’s typically tend to be pre-fader. Some DAW’s, like Harrison Mixbus, will allow you to choose between pre and post so you can pick whichever is more comfortable to you and makes the most sense to your workflow. It’s important to know how this works in your chosen DAW for several reasons. For example, If the master fader inserts are pre-fader, we’ll need to know how to control the levels of the signal hitting the master channel before any processing takes place. This is why many videos about gain staging mention the need to keep signal from “piling up in the master channel”. What most of these videos don’t tell you is that a standard trim plugin is linear and won’t change the sound in any capacity. It just turns it down. This means if you’re hitting the master channel too hot in a Pre-Fader system, you can simply use a trim plugin before your other effects to turn down the signal and ensure that you’re feeding the appropriate level to your master bus chain. Since I work in REAPER, and REAPER is Pre-Fader, I often use the HoRNet Track Utility for this task. I can make sure the signal hitting the master chain is calibrated to the level I want automatically.
However, if the master fader is Post-Fader, as with Pro Tools, there’s no need for a trim control. The amount of signal being fed into the master bus chain is changed by the level of the master fader itself, and the master fader is also a linear process. This means you can adjust the level of the master fader to ensure that you’re feeding the right amount of signal into your processing chain.
In both instances, I find it beneficial to have a VU meter plugin placed at the beginning of your master channel inserts. Pre-Insert chains can benefit from a VU that has a trim control built in, such as Klanghelm’s VUMT or Hornet’s VU Meter MK3. The trim control allows you to adjust the amount of signal hitting the meter, giving you one more point of control of your gain staging before the signal hits the processing chain of the master channel. Post-insert chains don’t necessarily need the trim control, but since the trim control is linear it’s not going to hurt anything to use a VU meter that has one. You can either adjust the master fader until the VU meter reads the level you intend, or you can adjust the trim control. The choice is yours.
So why would we want one instead of the other? Why do we have different configurations? That’s easy. Post-Fader insert chains more accurately mimic an analog console’s workflow. After the master fader, the signal of the console could be fed into an external processing chain. But the amount of signal hitting the processing chain would depend on the level of the master faders themselves. To keep things familiar and encourage people to migrate from consoles to ITB workflows, DAW’s like Pro Tools incorporated this into their system. However, DAW’s like REAPER working in a pre-insert fashion often feel more intuitive for those who learned in the box and haven’t lived in the analog world (people like me). This is where a trim control would come in handy as the first insert. It’s easy to use and is sonically neutral. If you’ve hit your master fader too hard, turn down the trim control.
In the end, when mixing ITB it’s really up to your preference of DAW and your own workflow. You should know how the master channel of your DAW works and how to control the level of signal hitting the inserts of the master channel. There isn’t a better option, just different approaches.