Earlier today I was on the website of one of my favorite DAW plugin authors, iZotope. Specifically, their page for the latest iteration of Nectar 3, which is a complete vocal processing suite in one plugin. There are lots of cool things in this software, most notably a frequency unmasking feature which works with other plugins in their software suite by communicating across channels and letting the user know which instruments are clashing at similar frequency regions. They have been leading the charge with this particular type of mixing aid for a couple of years now, and I used to be pretty excited about it when it first debuted. But now I'm like:
The problem behind the problem:
This is a really simple one. Frequency overlap between tracks in a mix is due to one problem and one problem only:
For example, let's use the extremely simple confessional-boy/girl-at-the-piano genre: are you going to play notes/chords that are in the same octave that you're singing in? NO. (Or, at least, you shouldn't.) You will leave musical space around the vocal so it fits in.
What's more, this idea of how to make a great mix has been understood by composers and musicians since the 18th century, if not longer. You want to hear the bassoon in a symphony orchestra? Then make most of the orchestra shut up, bring the volume level of the supporting instruments way down, and make sure they stay out of the range of whatever the bassoon is playing - and boom, there's the bassoon, no DSP/AI magic required. And it will always, Always, ALWAYS sound better.
A great example of good arranging:
Click play to listen*. Now, while you're listening and reading, take note that this album was recorded with minimalist microphone techniques (by Bob Katz). I don't know exactly how he did it, but I'm guessing he used 3-4 microphones at the most. So there is very little wiggle room to compensate for poor arranging by this group. With drums that are capable of deafening SPLs in the same space as a delicate classical guitar, it's a recipe for a musical disaster. Yet they pulled it off. How? Listen and find out!
And now, here is an example of arranging that could be... better:
And yes, I'm fully aware that I just made an example out of a song from an album that won the Grammy for Best Engineered Album (Non-Classical) this year, by one of the most respected recording artists of our time. But don't be distracted by any of that (I'm also leaving the artistry of the music itself alone - maybe for another time). Another reason I reference this song is for anybody who is running Logic Pro X v10.4 and later, who may or may not know that they have access to the complete session file for this song in their template chooser. If you are one of the blessed, you can see the 130+ tracks that make it up, and how many of them, at any given time, are effectively inaudible unless you solo them in the software. (So why bother?)
And even at that, the four or five elements that are going at any given time are all competing in the same frequency space (the speech intelligibility range - 1k-5k - no less); and while I can't speak for anybody else, this mix is like fingernails on a chalkboard to me. NO AMOUNT OF MIXING, no matter how expert, can fix it. Except maybe some creative use of mute buttons.
(In partial defense of the Grammy's, the other final nominees for the BEA-NC category were actually very well done and deserving of that honor. Check them out.)
IT'S THE ARRANGEMENT, SMART GUY.
* Please sign up for an Apple Music membership (if you haven't already) if you love to listen to music. Or feel free to search for these songs on whatever platform you prefer to use. But you would still do well to consider using Apple Music, as it is currently, to my knowledge, the most equitable service in the streaming market, in terms of compensating artists fairly for their streams. No, the streaming game is not perfect, mind you, but A.M. is the best thing out there given the current (sad) financial reality that faces most musicians. Please also note that I am not a brand ambassador for Apple. This is just free consumer advice.