One major new feature in Logic Pro X 10.1 is VCA faders and VCA grouping. In a large analogue mixer, a VCA (Voltage Controlled Amplifier) is a channel gain control. This allows the engineer to control several faders in a group all together while maintaining any offsets within them (and sends) by only moving a single fader. Your probably thinking you can achieve the same result by creating a AUX track to act as a group fader on several tracks in your mix, for example your drums. In this tutorial I’ll show you how they are different and why you should start using VCA faders.
VCA faders vs. AUX tracks
1. When you are working with effects from a post-fade send and use an AUX grouping method to bring down the level on the master sub-mix, you will end up with a wetter signal, because the gain has been reduced in the dry path but the wet path has stayed the same. In the circumstance of a VCA group setup, the group fader is changing the gain of each channel, so the amount of signal fed to the post–fade send also reduces by the same amount and the dry/wet balance is maintained – this is the desired result.
2. VCA groups can ‘group’ channels that are routed to different outputs, which would be impossible using conventional grouping and group faders when working with AUX tracks. It can be done, but it’s more time consuming than anything – not to mention confusing as to many tracks will be routed back and forth.
3. VCA Groups also use less CPU power than say a AUX group track. Anytime we can lower CPU power is good in my books.
One draw back using a VCA faders is the lack of automation options. You essentially can only automate the groups volume. In reality, you don’t need anything more than this. When working with a large session you usually want to create groups. One group for the drums, one for the strings, one for the vocals and so on. Using VCA groups in this manner can help you automated each section volume while only using 4- 8 faders – especially useful if you only have a 8-fader MIDI controller. Think about playing back a song in realtime with the ability to automate volume from section to section using a minimal amount of faders.
Watch this video to get a better understanding on the differences between using an AUX track and a VCA fader and why VCA fader can help on your mixes.