I participate in a forum for SAWStudio and SAC users. There was a question posed on the forum about mixing a recording. While the advice given was in the recording forum the principles apply equally to mixing live sound. The reply in the thread, written by Cary B. Cornett, presents information that reflects much of my philosophy in live sound mixing. I requested and received permission to reproduce the post here.
Cary's Forum Post
The real problem is the desire to make each and every element in the mix sound "big" or "fat". In my experience, you can have maybe 3 "big" sounds in a mix. Go for more than that many, and soon your mix will have a "cloudy" or "blurred" sound. The easiest way to avoid that problem is to have fewer sounds to deal with. An arrangement with "space" or "air" designed into it will be a lot easier to mix.
If you MUST have a bazillion sounds going at once, there are, as I see it, two different approaches to getting a decently clear mix. The first approach is what they did in the "bad old days": Pick the few things that really need to be clearly heard, and let everything else sort of blend into an indistinct background (Think Phil Spector's "Wall Of Sound"). The more modern approach is to "sculpt" most of the sounds in the mix so that they all make room for each other. If you could go through most of today's mixes and solo the different mix channels, you would discover that many of the individual parts/tracks sound "thin" or "wimpy" by themselves, even though the overall mix sounds good.
Here are some general "sculpting" tricks to play with (not invented by me, this all seems to be pretty standard stuff):
First sculpting tool: EQ
Start by cleaning up the bottom. Listen to a track. If it doesn't need low bass, put in the high pass filter, crank the frequency up until it starts to "hurt" the sound of the track, then back down to just below that point. If the part seems a bit "woofy", pull down the low frequency EQ a bit. Repeat with every track.
Too much "mid-bass" has a way of making mud. If a part doesn't need to sound "full", you might want to make a broad dip centered somewhere between 200 and 400 Hz. Even a modest dip here, applied across several tracks, will noticeably improve "clarity" in the mix.For any track, look for frequencies to cut rather than boost.
If there are two parts that seem to fight for the same frequency range, find a way to EQ them to sound different from each other. For example, you may want to slightly boost a given band on one track and slightly cut the same band on the other.
Second sculpting tool: Volume
Usually making everything loud is a mistake. Select certain parts that MUST be dominant, and let all other parts be a bit quieter. For any part that doesn't have to dominate the mix, see how low you can set its level and still hear it. Stuff with really strong upper mid and top end can often "cut through" and be heard even at a limited level.
Third sculpting tool: Panning
A really well-balanced mix should still stand up in mono, but you can still use panning to move competing sounds (parts with similar frequency range/tone) away from each other on the stereo stage.
There is a ton of other stuff you can do (remember whole BOOKS are written about mixing), but these bits should start you on your way.HTH
Cary B. Cornett
Book of the Day
This witty and informative book demonstrates the finer points of live sound mixing from the perspective of an industry veteran with a proven track record.Check It Out