All About The Stems
Stems is just a catch word for an audio track containing an element of your song (verse, hook, snare, bass etc). The quality of these tracks is of immense importance as they establish the 'ceiling of awesomeness' that the resulting mix can achieve. Remember that a mix is not a live performance. In a live performance the audience can feed off of your energy directly. More importantly, a live performance exists for the duration of the song/set and when it ends it exists only in the hearts and minds of your audience (like theater). A mix is forever (like film). That one part you wish you had done just a little differently slowly drives you mad with time. Because recorded music is made to be listened to again and again, precision has become a bigger and bigger deal. I have worked on dozens of concert videos and can tell you that even those 'live performances' are highly edited before distribution. A good engineer will make great stems into an awesome mix. Conversely, the same engineer, with great effort, may be able to turn bad stems into an acceptable mix.
So what is a quality stem? One with a high signal to noise ratio and one that captured a high quality 'image' of the sound source. We'll avoid the 'tracking' (recording) rabbit hole and stop there...
So, back to mixing, let's assume we have our high quality stems. In the perfect world, most engineers would start with cleanup and recon work. This would involve removing/lowering noise between audio content, performing basic repairs (swapping flubbed note or or fixing a mic pop), dialing in breaths and so on. This would also involve listening through all the tracks and making note of 'cool licks' that should get their day in the sun. This also gives engineers a chance to acquaint themselves with the piece. Remember that the first time they heard your piece may have been when you walked in the door. This 'listen through' will help them to make quality editing and mix decisions and get the most out of your piece. This step is usually the one sacrificed during a 'quickie mix'. It is also (along with pitch and timing) the source of the most common complaints brought up after the fact. So if possible, do not skip this step, as it is foundational and, like 'stem quality', will determine how great a mix can be.
THE DIY OPTION
If money is an issue and you have a set up of your own, you could do this step before you deliver the stems. Just make make sure the edits are clean and the stems are as dry (unprocessed) as possible. Another possibility is that you could make a note of any needed edits/cool bits and share that with the engineer when you deliver the stems.
PITCH AND GROOVE
The next part of editing would be pitch and timing. No matter how good the musician, in today's commercial market, these edits must be made. In 'live' and 'classic era' work it is done with a very gentle touch, but it is still done. Otherwise, with each listen through, the flat note here or the 'out of synch' rhythmic passage there will sound more and more prominent until you want to claw your eyes out.
Once again if money is an issue and you do the recording yourself, you can make sure the takes you keep are as accurate (pitch and timing) as possible. In vocals pay close attention to the ends of phrases as they tend to go flat. Guitars and basses should be tuned continuously, especially if they are to be paired with keyboards or other 'perfectly tuned' elements. Make sure that the rhythm section is tight, particularly drums and bass, as they constitute the rhythmic foundation of the whole piece.
The editing phase is an extremely important but often overlooked part of mixing. It is best to address these issues first, as many mixing decisions will be based on the initial stems/edits. A stem change after the fact could invalidate hours or even days of work. This can put great strain on the artist/engineer relationship, especially if working within a flat fee arrangement. Next time we will discuss some editing tricks and delve into the 'rough mix' phase.