VCA stands for “Voltage Controlled Amplifier”. VCAs have traditionally been used in analog consoles to control the amplification of several individual signals with a single fader. This works sort of like a remote control that allows you to group together complex mixer channel structures and control them using VCA group faders. This functionality is also built into modern DAWs. We’ll show you how you can use VCA groups to set up a fader management system and give yourself more control and oversight when mixing several single channels together.
As an example, we’re going to use a drum recording which is split up onto seven tracks/channels.
To help make the difference between audio groups and VCA groups clear, let’s go through a few preliminary steps first:
Snare reverb via AUX 1
Step 1: Create a new channel in the mixer by right clicking on the number of the last drum channel and selecting “Insert Tracks” > “New AUX bus”.
Step 2: Select “VariVerb Pro” under “Delay/Reverb” in the new AUX channel and set the algorithm to “Plate A”.
Step 3: Now to go to the uppermost slot of the AUX section in the snare channel and drag to the right to increase the reverb effect feed.
Step 4: Open the VariVerb graphical interface by right clicking on the plug-in slot and adjust the parameters so that the reverb harmonizes well with the snare.
Create an audio group (also called “audio subgroup” or “submix bus”)
Step 1: Create a new channel in the mixer by right clicking on the AUX channel number and selecting “Insert tracks” > “New submix bus”.
Step 2: Select all drum channels by clicking on the number of the first channel (Kick) and then holding down the shift key and clicking on the last drum channel (Compressed).
Step 3: Now set the output for all drum channels to “Bus 1”.
This allows you to control the total level of all drum instruments via the submix bus fader.
Create a VCA group
Step 1: Create a new channel in the mixer by right clicking on the AUX channel number and selecting “Insert tracks” > “Insert empty track”.
Step 2: Double click on the name field of the channel and name it “VCA_Group”.
Step 3: To properly turn this channel into a VCA group, press the “VCA” button and select “Fader is VCA Master”.
Step 4: Now we need to place the individual drum instruments in the VCA group: Select all the drum channels by clicking on the number of the first channel (Kick) like you did before. Then hold down the shift key and click on the last drum channel (Compressed). Clicking on the “VCA” button now and selecting “VCA_Group1” will assign all selected channels to the VCA group.
The VCA group fader now controls the level of the assigned single channels. This is represented by the “ghost faders” shown in the image.
Of course, you can still adjust the level of the single channels individually.
I. Audio groups vs. VCA groups
You’re probably asking yourself now what the concrete differences are between audio groups and VCA groups.
A) Channel signal to post-AUX sends
An audio group controls the total level of all single channels assigned to the group. A VCA group effects all individual channel faders assigned to the group. To make this difference a bit clearer, try the following:
Step 1: Start playback.
Step 2: Gradually drag the audio group (“Bus 1”) fader downward.
As you can hear, the total level of all channels combined decreases, but the snare’s reverb signal remains unaffected.
Generally speaking, this means that all the effects signals being fed through the post fader AUX channel are reduced to a sum total independent of the audio group signal level.
If you want to maintain the ratio of the direct signal to the effects signal, you have to adjust the AUX send feed in accordance with each change in level made to the audio group.
Using a VCA group lets you avoid having to do this:
Step 1: Set the “Bus 1” group signal back to 0dB and start playback again.
Step 2: Now start gradually dragging the “VCA group” fader downward.
As you can hear, by reducing the VCA group level, all single channel signals—as well as the post fader AUX send feed—are automatically reduced as well. This way the balance between the direct signal and effects signal remains the same.
B) Insert effects and audio output
Another difference is the fact that the audio group (as compared to the VCA group) has its own audio output, meaning it has audio outputs at its disposal, and offers the possibility to further edit the sum total signal with insert effects.
Step 1: Select the Samplitude dynamic tool “AM-Munition” in the plug-in section of the “Bus 1” audio group to edit the group signals.
Step 2: Use the preset “Mastering > Rock > Rock MS” to optimally compress the drum sound and achieve a loudness gain as well as give it a characteristic tube sound.
The VCA group, on the contrary, works purely as a remote control for multiple channel faders assigned to it. No audio signal runs through the VCA group channel fader itself. For this reason, the VCA group does not have insert functionality or its own audio output. You will notice that no output level is displayed for the VCA group.
Hint: Go ahead and try adding an insert effect to the plug-ins section of the VCA group. You’ll notice that no changes are made to the signal in the “VCA group” channel.
II. Combining audio and VCA groups
To get the most out of audio and VCA groups, we recommend you use a combination of both like we did in the example.
This lets you easily control the level of the instruments in the group with only one VCA fader while being sure that the direct signal/effects signal ratio won’t change. Plus you can continue editing the sum total signal with insert effects as well as routing it through the audio group to all available audio outputs.
Note: As long as the audio group fader is set to 0dB (Unity Gain), the output display for the audio group also counts as the output display for the combined channel in the VCA group.
III. Mute groups via VCA group
Due to the fact that when a VCA fader is muted no channel signal is sent to the post-AUX send, the VCA group lends itself well for use as a mute group.
Step 1: Start playback.
Step 2: Click on the VCA group channel “Mute” button. You will notice that you don’t hear anything, snare reverb included. And this is normally what you want out of a mute group.
By contrast, when you use the audio group “mute” feature, even though the drums are muted, you can still hear the snare reverb.
IV. Solo group via VCA group
Step 1: Start playback.
Step 2: Press the VCA group fader “Solo” button.
Depending on which global solo mode you have set, you will hear the VCA group channels in PFL (Pre-Fader Listening) or AFL (After-Fader Listening).
In the following audio sample you will hear the drums being listened to in the “AFL” global solo mode via the VCA group’s “Solo” button.
V. Automating the VCA group
Lastly, we want to automate the VCA group. Automation will effect all channels involved. Here you can also take advantage of the fact that the direct signal/effects signal ratio will not be effected by the VCA group when you adjust the level ratios. Any automation curves you have already set for instruments in the VCA group will naturally be taken into account.
Step 1: Create an automation curve for the volume of the hi-hat by activating the “Vol” button in the track header, then right click in the automation section in the track editor and select “Touch” mode, start playback and use the fader to adjust the volume on the fly.
Step 2: Now create an automation for the volume progression of the VCA group in the same way.
Listen to the effect the two automation processes have on the hi-hat.
The last audio sample will let you hear the combined result on the entire mix.
We hope you have lots of fun mixing with VCA groups.