Topics for this post include Subgroups and AUX busses on mixing consoles. Subgroups can really simplify managing the mix, especially if your services are very dynamic. AUX busses are a necessity as well if you are running your monitor mixes from the same console as the FOH, and I will also elaborate on how I use AUX busses for my record mix.
Subgroups are smaller (sub – below a full mix) mixes within the main mix generally. Here’s how I use mine (on a Mackie SR32.4) and why: I assign my vocal mics (for singing) to subgroup 1 by first depressing the button on each vocal mic channel labeled 1-2, then turning the pan control to the left which narrows the scope of the signal down to subgroup 1. I assign my two speech mics to subgroup 2 by again depressing the 1-2 button and turning the pan control all the way to the right. I assign my instruments to subgroup 3 by depressing the 3-4 button and panning all the way left, and lastly I assign my six drum mics to subgroup 4 by depressing the 3-4 button and panning to the right. What this allows me to do is run most of the service with 5 or 6 fingers. Once I have established the balance of the vocal mics (by pressing the solo button on the Subgroup 1 master channel strip) I can adjust vocals as a whole with a single fader. Same with my instruments on subgroup 3, the speech mics (for speaking, a wireless Shure LX series handheld with SM87 head, and an old AT W series with 831c lav), and the drums on subgroup 4. Because of the way I have my record mix setup (or should I say I setup my record mix this way because) I can tweak the speech mic level going to the record mix by adjusting the channel fader for that mic, and while watching the level meters on the PMD570 recorder simultaneously trim subgroup 2 to maintain the appropriate level at FOH. If the voice (person) leading a given song changes I can always trim up that channel’s mic to bring it out in the mix, and I may pull back subgroup 2 as well, depending on what kind of level we’re already at and if the other vocalists will be coming in at all. But you get the general idea: make your fine mix adjustments with the individual channels (by using the solo button on the associated subgroup master channel strip), then make the coarse adjustments with the subgroup. And again, note that this allows my record mix through the AUX busses to work out the way I want which I’ll explain. One thing that I know generates confusion about AUX busses is the whole “pre-fade” and “post-fade” thing. What this means is that the signal feed to a given channel’s AUX 1 control (being pre-fade, for instance) is pulled from the channel before the channel fader. Which means what? You can jack the channel fader around all you want and the level of that channel’s signal going into the AUX 1 mix (presumably a monitor mix) will not change. Which is how we want it 99% of the time; we don’t want to mess up the person’s monitor mix when we make a change to the FOH mix. Post-fade is the opposite, the feed to that channel’s AUX buss 3-6 (on the Mackie, and 3-4 is switchable) comes after the channel fader. Which now means that it doesn’t matter how high you hack the AUX 3-6 send on that channel, if the fader is all the way down, the most you’re going to get is maybe a smidge of crosstalk. Post-fade sends (tech speak for AUX buss) are used for effects such as reverb and delay, and also for record mixes (at least in my setup.) My theory on this is that if I need to trim a vocal channel or the speech mic for the house, then I would also want to trim it for the record. The trick is getting the AUX level set for each channel so that that relationship works for both mixes within tolerance. But that’s also the beauty of it – I can setup a different mix for recording than I use for live, which means I can use ambiance mics for the record and just not assign them to the FOH mix. And I feed the PMD570 into the tape in on the console so that I can monitor the record mix from the console as well – including the processing I’m doing between the console and the recorder, a Behringer Ultramizer (which I wouldn’t recommend to anyone.) It was a good idea in theory, but the hard compression that this unit applies means all it’s good for is a fancy limiter. Being 2 bands it does allow you to reduce some of the brutality by setting the crossover point just high enough that thumps and bumps and heavy low end don’t bring the entire mix to its knees. And why am I doing all of this? So that when I get home with the flash card I can have a good solid recording that only requires some simple edits in Fission, final MP3 encode and it’s ready to upload. See what you think of the results, our sermon downloads are here and here. Low bitrate versions are encoded with iTunes using this workflow. So, back on the main highway here, a very general guide is that you use pre-fade AUX busses for monitor mixes and post-fade busses for effects (but not processing devices such as compressors since in general they’re meant to be inline devices, not mixed in in a parallel fashion (as you typically would with reverb or delay), and to feed recording devices and/or even distributed sound speakers in the nursery or bathrooms. Our distributed feed is tapped off the output of the Ultramizer, which is feed by AUX 5 and 6. Which brings me to the last thing I want to cover, using a pair of AUX busses to generate a stereo mix for your recording device. I’d love to run a multitrack recording of our services, at least in theory, but that’s not a real need now and just another way to burn up 8 more hours of my precious time. So, for a time I was using AUX 5 and 6 for Left and Right channels, respectively, to generate a stereo mix for recording. What you do to “pan” a voice or an instrument is adjust the AUX 5 and 6 controls differently, for instance; to pan hard left you only turn up the AUX 5 control for this channel, and leave AUX 6 all the way down (and then feed AUX 5 to the left channel of your recorder, and AUX 6 to the right.) To pan in the middle just adjust 5 and 6 to be the same. And for somewhere in-between adjust one AUX slightly higher than the other. That’s the down and dirty way to pan. When we regularly had 2 guitarists playing it really added some nice width to the soundstage of the recording to pan each one fairly hard to one side and the other, and of course panning the cymbal mics and toms, and the vocals.
