CTA Classroom: Using Auxes, Groups, VCAs & Matrixes Pt. 3

After our little theory discussion on how Auxes and Groups work, let’s get into some practical application. I’m not going to try to be exhaustive here; there are many, many different ways to use all four types of controls. But hopefully, this will give you some basic ideas as to what you can do with these things. 

Using Auxes

The most common use of an Aux send is for a monitor mix. The rule of thumb for this is to use a pre-fade mix (that is, the house fader will have no effect on the aux mix) for monitors so that any mixing changes you make in the house will not effect the monitors. On most desks, aux mixes are mono, but sometimes you can combine two auxes to form a stereo mix. Stereo is ideal when using ears, though occasionally we’ll see stereo wedges. Different consoles make stereo auxes differently, so consult your manual.

On this console, the first 4 auxes can be paired in stereo with a button press. Notice the pre button to set a pair (1&2, 3&4, etc.) as pre- or post-fade. Image courtesy of APB Dynasonics.

Think of each row of aux controls as another row of faders, but instead of moving up and and down, they rotate. By adjusting the levels of each of your channels in an aux mix, you build that mix for a monitor. At least that’s one use.

The second most common use of an Aux is for effects. Let’s say you want to put some reverb on your vocals. Now, you could buy a reverb unit for each vocal, and insert it on each channel. But that gets expensive and complicated, and it’s tough to control when the reverb is on or off, and how much reverb you have. The smarter way is to use an aux mix. FX Auxes are typically post-fade because if we turn the channel down in the house, we also want less of that signal going to the effect unit.

In this case, you’d take your vocals, and send them all to a post-fade aux. The output of that aux goes to your reverb unit. The output of the reverb then comes back in on a return or another input channel. You can now control not only the level of reverb that gets added to the mix (by the return channel), but you can also control how much of each vocal goes into the reverb. You may want to vary that depending on the voice. 

You can also use an aux mix to create another mix for broadcast, a cry room or lobby or a board mix. In this case, you’d probably want to use a post-fade mix so it will track your mix. But you can add in more of the pastor’s mic and less of the band channels so it balances out better. While you can do this, I think there’s a better way, which leads me to…

Using Groups

If you only have groups and no VCAs on your console, you can use groups to control larger chunks of your inputs via a few faders. For example, you could set up a band group, a vocal group, a playback group and a speaking mic's group. So as you’re mixing, if you want to boost the vocals a little bit, you simply push that group up and all the vocals go up. Handy, right? There’s more!

You could also use the groups to turn the entire band off with one switch. Most times, groups will have a mute on them, so with a single button press, you mute the band. But there’s a catch; this will not typically mute the aux sends, so your monitors will still be hot. So you’ll still have to deal with that. 

In this case, we've used 4 of our Groups to split the band up into manageable chunks. Image courtesy of APB Dynasonics.

Another way to use groups is to break up your band into parts; drums and bass on 1, guitars on 2, keys on 3, vocals on 4, etc. Now you have a little more fine-grained control over the mix. To use either of these methods, you would simply assign the individual channels to the group you want, but not the L&R group. Next, assign the group masters to the L&R mix. This is kind of a poor man’s VCA approach. But wait, there’s more!

I use groups for a few things. The first is for parallel compression. I send my drum mic's (all 8 of them) to two groups, a normal drum group and a drum spank group. I do this to keep the processing paths the same length so everything stays in time. The normal group is unprocessed, but the drum spank group has a compressor on it. I compress the entire drum kit, then mix varying amounts of spank into my mix as the song requires. 

I occasionally do the same thing for vocals if we have a big event and multiple people will be doing lead parts. I’ll use snapshots to send them to the vocal smash group and mix that in. That way I don’t have to double-patch every potential lead vocalist. 

In the Aux section, I was talking about creating a broadcast or lobby feed. Here is another great use for groups. I have four groups set up and every input goes to one of them; band, vocals, speaking mic’s, playback. Those groups are combined in various levels in my matrix (which we’ll get to next time) for various outboard mixes. I have a lobby/cry room mix, a video mix, a board record mix, and a CD record mix. I’m not really using these groups to mix per se, because the relative levels of each input happens on the faders. But the groups are used for level-balancing. Because music is 20-30 dB louder than speech I add some more speech into my outbound mixes to keep the relative levels closer. I then have to compress those feeds less, which keeps everything sounding better. Clever, huh?

You can do more with groups, but we’ll stop there for now. Next time, we’ll wrap this up with some uses for VCAs and the Matrix.

Today's post is brought to you by GearTechs. Technology for Worship is what they do. Audio, video and lighting; if it's part of your worship service, and it has to do with technology, GearTechs can probably help. Great products, great advice, GearTechs.