I talk a lot about how one of the first steps in building a great mix starts with getting great sounds from the source, making sure the instruments are sounding their best before you put a mic on them. Drums should be tuned and the heads in good shape, guitar tones dialed in, etc. that's the obvious, but it also includes balancing keyboard patches and playback tracks.
When you’ve got a keyboard player with a variety of keyboards, synths, and rack full of sounds it’s very important to work to get not only the levels, but the tones balanced.
It’s equally important with playback tracks or stems that can come in many different configurations and from many different sources.
I’ll start with keyboards
There is often a big difference in what the keyboard player hears coming from their keyboard rig through their IEMs and wedges, versus how it translates through the PA.
For example, they could be compensating with extra high end on a patch to cut through their wedge mix, but that extra high end is far too much for the FOH mix or cutting the highs because they’re killing him in his IEMs.
This becomes a problem when you’re trying to get that string patch to cut through in the house. Of course, you could always add some top end with the EQ on the channel but when the keyboard player switches to a different patch, for instance, some crazy synth sound that’s just screaming, you’re left scrambling to undo the EQ you just did.
The ideal thing to do is first work with the keyboard player to understand what they are looking for in their sounds. Get things sounding right in the PA and then let the monitor engineer adjust the mix on stage to compensate for any changes needed to cut through or fatten up the sound in the monitors.
You want to avoid a situation where the keyboard player is constantly making adjustments to the levels and sounds they are sending you during the show. Consistency is key when mixing live music.
When the keyboard player starts altering his/her levels and tone during the show, it's not just affecting you, it's affecting everyone else on stage with keyboards in their mix. So now you or the monitor engineer have got three out of the five band members waving at you to bring the keyboards down in their monitors.
If the keyboard player needs more high-end to cut through their mix, those adjustments should happen in the monitors, not the keyboard rig itself.
You should also spend time working on getting the levels between patches to be as consistent in volume as possible. This is especially important if you’ve got a variety of different sounds or several keyboards sub-mixed down to two channels.
Compression is an option, but there comes a point when you have to make a decision between hitting those channels with significant compression and sucking out all the dynamics, or having uncontrolled sounds jumping out of the mix unexpectedly. Having consistent keyboard levels is much better. So whatever you can do to make sure the levels coming to you are consistent and the tones are balanced, will be of great benefit to your mix.
Stems and Playback tracks
Stems and playback tracks often present their own set of complications.
Depending on the act that you are mixing, the likelihood of your show containing at least a handful of playback tracks is very high. With the current trend of pop music and other genres employing a multitude of producers or 'beat makers' on every single song, it's very common to have tracks/stems coming from more than one source/producer.
This translates to very little consistency of instrumentation or levels on the stems from song to song. Some producers will only hand over a stereo mix of their stems, some will provide a breakdown of all the individual stems. There are many possibile combinations of everything in between. More often than not the stems or tracks will need some or a lot of work.
For instance, your breakdown of stems from producer #1 for Song A is:
Stereo Drums that include- Kick, Snare, Toms, Percussion,
Mono channel of Bass guitar
Stereo channel of Horns and Guitar
Mono channel of Acoustic guitar and fiddle
Stereo Background vocals
But, your break down of stems from producer #2 for Songs B, C, and D is:
Mono channel- 808 kick drum sample and synth bass
Mono channel hand claps
Stereo channel Synth 1
Stereo channel Synth 2
Stereo channel Strings/ horns
You stems from producer #3 are a left/right mix.
And so on...
Hopefully, you’ve got a talented Programmer with you that can arrange things in a way that makes sense and works for both you and the band.
First, decide on how many channels you can allocate to playback and what each will contain. Group things in a way that makes the most sense for ease of mixing. Keep in mind, you'll need to consider what the band members need in their monitors. If you've got a ton of key and synth stuff on stems including string patches, horn patches, organ, piano, etc. You may choose to combine all of that into two channels. However, the band needs the strings, piano, and organ in their monitors but none of them want the horn patches.
After you decide on the number of channels to be used for playback, and you re-arrange them to meet everyone's needs as best they can, it's a great idea to work with the Musical Director and or programmer to balance the levels between all of the tracks.
You want everything coming to you to be as consistent as possible. Again, a little compression to keep things in check is fine, but you shouldn't be dealing with 10db level changes between songs.
It's all about the Bass
Much of the time, when stems are being prepared in a studio there is a tendency to overcompensate with the Bass. What happens is the level on the Bass tracks is boosted so much that when played over a PA system, the bass is overwhelming and can easily drive the system into compression.
If time allows, I suggest spending an hour or so with the MD or Programmer (whoever is responsible for the tracks), and listen to the tracks by themselves in the PA. Listen to how they translate over the sound system. Aside from adjusting the bass levels, other stems may need some tweaking. You may find certain things get lost in the mix when the band is playing and they will need to be boosted in the tracks to cut through.
Finally, when mixing playback tracks with a live band, there can be an obvious difference in the sound of the tracks vs live instruments. Apply EQ to create a more consistent sound across all of the inputs.
Once again, start with great sounds at the source. Work to get the tones and levels as balanced and consistent as possible before they come to you and this will make your job of mixing much easier.