I recently conducted a workshop at a nearby church that had quite a sophisticated audio system. Line arrays that covered the sanctuary with front fills, under balcony speakers, personal monitor mixers for the vast array of musicians and a 48 input digital mixer. As I was observing their rehearsal, I noticed the sound operator was sound mixing with all of the console’s inputs. Yes, he was sound mixing with forty-eight faders. Some of you may be asking: “Is there another way to mix?” Yes, there is an easier method and it will save you hours of frustration if you will take some time to learn how to do this. It won’t take long.
Sound Mixing With Groups
After you have identified the channels with their appropriate inputs: voices, instruments, playback sources, you will want to organize them into groups as soon as possible (i.e. Drums, Guitars, Vocals, Keyboards, etc.).
There are two ways of doing this on all mixers. If it’s an analog mixer, you will have Sub-Groups and, on some higher end mixers, you may have VCA (Voltage Controlled Amplifier) Groups. Digital mixers most often will have sub-groups and the digital equivalent of a VCA, known as a DCA (Digitally Controlled Amplifier).
There are similarities and differences between Sub Groups and VCA/DCA.
What is similar is that I can take individual channels that are similar, like drums, and place them in a group that can be controlled by that group’s fader. By raising (boosting) or lowering (attenuating) the group fader, I can raise or lower the level of all the channels in that group. Imagine (not so hard) the drums getting louder during the worship and overwhelming the vocal. Are you with me? Instead of using eight fingers to lower the level of each drum channel, you could use one finger on the group fader, to attenuate the level on all of the drums simultaneously.
Expand that idea now to include other groups of instruments and you’ll begin to get a picture of how much easier a service or a performance would be to mix when using fewer faders. The fewer controls that you have to deal with will reduce the confusion. Virtually every analog mixer has at least two sub-groups, typically called Left/Right Master. Instead of running everything in Mono/Stereo, these could be used as sub-groups. With a pan control I could assign all of the band’s instruments to one group and vocals to the other and do a whole show with two groups. Some mixers will have four or eight sub-groups.
You can see in the illustration below how I’ve organized my inputs into groups. I am now sound mixing with five faders. My lead vocal is in Channel 16 and the four sub-groups are right next to it. If the band is starting to get louder, I can slide over to the groups and pull down their level, or push it up. This is way easier to mix and maintain control than by using every input.
VCA and DCA Groups can be used in the same way as sub groups, but there are some differences.
DCA is actually a remote control for the channels assigned to it.
So as I change the DCA fader up or down, the channels assigned to it will follow.
That’s all it does.
Sub-Groups
Sub–groups are different, in that the channels assigned to them are actually being grouped together into a virtual sub-mixer. One advantage of this is that I can add processing to the whole group. For instance, I may have a compressor on the kick drum, and one on the snare, with EQ applied to each drum on every channel. However, with a Sub-Group, I could put a compressor/limiter on the whole group and EQ the entire drum set as a whole, as one instrument, which would make for a more cohesive, tighter and blended sound. There are some tricks I can do with this application. One would be what we call parallel compression, which we will discuss in a future article.
It’s not possible to do this with a DCA.
Sub-groups will also add level to the individual channels. Please be aware of that as your gain structure will be affected. DCA groups do not add/diminish level.
Sub-Groups will also have a physical output from your mixer to feed speakers or devices where you need to send a sub-mix, i.e. under balcony, front fills, foyer, etc.
DCA groups do not have physical outputs.
Groups can also be muted. Rather than mute 8 drum microphones at once, you can hit the mute on your group and all the assigned channels will be quiet.
Many of the new digital mixers will have sub-groups and DCA groups. In this case, you have options as to how you want to control your groups and if you have a need to use sub-groups for feeding delayed speakers and other applications.
Most of the time you will be limited to how many sub-groups and DCA groups you have to work with. DCA groups are typically limited to 8. On much more expensive mixers, you may yield as many as 12. The Presonus StudioLive 32 Series III is exceptional in its class as it touts 24 DCA groups.
You Might Be Asking, What On Earth Would I Do With All Of Those Groups?
We’re in an era where we are using multiple microphones on kick drums, snare drums, guitar cabinets, multiple keyboards, Leslies, etc. Imagine having a drum group and also having access to groups that cross populate with a kick drum group and a snare drum group. Or you could set up groups that have effects returns or multiple microphones on a guitar amp. This allows for very flexible and ultimate control.
In the next article, we will attempt to demystify Matrix Mixing. This is another area where many church volunteers get confused and once understood, can go a long way in helping you to solve issues related to sending mixes to various destinations in your facility.