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.

VCA Automation

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.

  • Johnson Detlev

    Question on that: If you are lowering the gain of a channel via a VCA fader, does that mean, that there is less gain fed into the insert plugins? Or does that reduction happen after the insert effects?

    • imamusicmogul

      Good question. No, it does not effect the gain fed into the insert plugin as that will always stay as you set it. It will only effect the level being sent out to AUX tracks and of course the overall signal of your track.

  • Aldy Waani

    So basically it’s just a fader that control a group of channels? What’s the different with ‘Groups’ in Logic 9? I assigned 8 channels of drums to a Group and all 8 Faders will move all together. Just prepare a track with 0dB and include it in the group to be the VCA. Is it the same thing?

    • imamusicmogul

      VCA is also control the proportionate send amount on any of your buses. That is the main difference between VCA and a group.

  • André Paixão

    that was so cool. tx a lot

  • Kevin By

    wonderful! thanks alot…highly valuable. I’ve been often times annoyed having to mute sends when wanting to isolate certain group aux.

  • Paulo Clayton

    The only issue I see is normally when I’m bussing tracks (i.e. drums), I’m also using a plugin on the drum bus like SKNote Disto, and the VCA track doesn’t have plugin slots. Wondering how I’d be able to make this part of my workflow… Perhaps control the drum submix as well as my parallel comp I’ve got for kick & snare? I’ll have to try that.

  • gatorsmash

    what if I have some bus tracks set to prefader? Does the VCA affect the signal to the bus?

  • Mickowest

    Thanks for that VCAs are great but you don’t seem to able to put a plugin on the fader, whereas you can on a aux bus…
    If I wanted the drums to distort, how can this be achieved using VCAs? Many thanks