If you were to ask 10 sound engineers how they build their live mixes, you'd probably get 12 different answers. Everyone tends to go about it a little bit differently, which is a product of the bands they're working with as well as the fact that in live sound, you work with what you've got. Even with all that variation, however, I think there are some common elements that most engineers use to achieve the result they're after.
Regardless of how you build the mix, I think it's important to develop a process that works for you and stick to it. Randomly bringing up instruments and vocals may result in a good mix once in a while, but for more consistent results, stick to a process. Your process will be based on your equipment, the band and the style of music you're mixing. It's important to note that what works for [insert name of famous mixing guy] here might not work for you; that's OK. Learn what you can from as many people as you can then work your own system. Here are a couple of ways to approach mixing.
THE TOP DOWN APPROACH
Some mixes start with vocals and build the music in behind. This was a reliable technique back about 10-15 years ago when worship music was very vocally driven, and the music was really a back- ground track for the vocals. When building a mix this way, you'd start by bringing up the vocals to the desired level, then start working your way through the band. Often, the second layer is guitar and/or keys de- pending on the orchestration. Drums and bass are usually left to the end so as not to overpower the vocals.
There's nothing wrong with this approach, especially if the music your church sings is largely led by vocals and/or a choir. In this case, the vocals should be right out front with the music playing a supporting role.
Modern worship music has changed, though, and I think there is a more efficient method for building mixes if that is your church's style.
THE BOTTOM UP APPROACH
Most modern worship music has much more of a rock-n-roll heritage, and is really driven by the drums, bass and guitar. Vocals are still important and need to be very present in the mix, however a solid foundation is critical to making this style work. In this case, mix engineers generally start at the bottom with the kick, the rest of the drum kit and the bass. Some guys like to do kick and bass together as those two sounds really form the foundation of the mix. Drums, guitars and keys are layered in on top to create a solid wall of sound, with vocals brought in at the end.
Going this route will probably lead you to mixing at a higher sound level than the top down approach—and I think that's OK. Modern worship music needs to be louder than praise team-style music. It's important to have a goal in mind when you start and keep track of your levels as you build. If you start the foundation too loud, by the time you get to the vocals, you could be way too loud. Don't fret, go back to the beginning and start again.
In modern music, you may need to spend more time getting the kick to relate properly to the bass—then layering in the snare, hi-hat, toms and overheads. Some like the toms right out in front with the snare, others prefer to set them back a little further. Again, the style of the music will dictate their placement.
WIDE OPEN SPACES
In keeping with the older/newer theme that's developing, let's consider effects and “space” in the mix. Older praise music (think Sandi Patti or Maranatha) utilized a lot of vocal reverb and typically had a lot of space in the mix for that reverb to decay. In a mix like this, you would rely on plenty of reverb and keep the instrumentation simple and in the background.
You might also use quite a bit of reverb on the drums and a good bit of compression on the guitars and bass to keep their levels in check. Again, if this is the style of music at your church, this is how you want to mix. And again, modern music has changed this paradigm.
IT'S MY DENSITY
Modern music tends to be much more dense, and by necessity tighter. You can't have a really full mix of guitars, keys, bass and drums that sticks together well if there's a ton of reverb bouncing all over the place. When mixing today's popular music, it's typical to have just a little bit of reverb on the vocals to air them out a touch, and possibly some simple delay as well.
You might find some reverb on the drums, but it's typically going to be pretty tight; maybe a short plate, just to make them sound more “live.” In this style of music, you're going to have multiple sources all coming at you at the same basic level,
so it's going to be important to give them their own space—not with reverb, but with frequency selection.
LAYERING WITH EQ
If you think of a mix as a layer cake, with low frequencies at the bottom and higher ones on top, the idea of mixing with EQ can start to make some sense. Perhaps mixing with EQ is a bit of a misnomer; you can't EQ a bass guitar to sit on top of a vocal (at least from a frequency standpoint) and make it sound good. However, by choosing to accentuate certain frequencies of each instrument, you can give them their own space and keep the levels up where they are prominent in the mix. For example, if you have two acoustic guitars on stage, it might be prudent to listen to their tone acoustically, and then roll off some of the highs of one, and the lows of the other. That way, they're not playing on top of each other and are both heard distinctly. Done right, this also takes them out of the vocal range and gives the mix a more three- dimensional quality.
You can also use EQ to create some space for vocals—by scooping out some space from instruments that are competing with them. A few dB deep by 1.5 octave-wide dip centered at 180 Hz in the piano channels can really make a male vocal stand out more, for example.
At the end of the day, the style of mixing is subservient to the style of music. Trying to mix vocal-heavy praise music like modern rock will result in frustration for all. Reversing that will lead to anemic sounding mixes that have no power or life. As engineers, our job is to serve the musicians and music. When mixing live, we can only work with what we're given. It is incumbent upon us to understand the music well enough to be faithful to the style.
