UPDATE: This article appears in The Ultimate Guide to Creative Mixing on the Digico SD5.
Have you ever had to mix some really dense backing tracks that made it impossible to find a place for the vocal?
When I was working on building the mix for the Ringling Bros. Out Of This World tour I ran into exactly this problem. Not only did I have a very mid-range dense arrangement, but there was an equally dense sweetener track mixed in at the same volume. The musical director was asking for more sweetener and I was struggling to find a place for the main vocal. The vocal was fighting to be heard over everything else going on.
The solution: a ducker.
This is the first time I relied so heavily on a ducker to make the mix work, but it was pretty simple to set up. I simply inserted the ducker on the channels that were giving me the most trouble and set their sidechains to the main vocal. I set the reduction to as much as 5 dB, which would have been too much with that channel soloed, but you could hardly tell in the context of the entire mix and it was just the amount of help I needed to pull the whole thing together.
I used the same trick on the bass and the some of the low-end heavy synth patches to help with the kick as well.