Capturing the energy of a live performance can be one of the more challenges pursuits an engineer faces in their career. While modern digital consoles have made multitrack recording in a live environment almost seamless, successfully putting out a killer-sounding live mix is another task altogether.
Be thankful you no longer have to lug around a 500 pound Studer A827 to get a 24 track recording of your live show, though many engineers did for decades. Since the days of analog, FOH engineers have gone from 24 track hard disk recorders to multiple input interfaces to building interfaces for DAWs right into digital consoles themselves. Audinate has even taken this a step further with the Dante audio network, a protocol that allows un-compressed, multi-channel, low-latency audio to be distributed over ethernet networks between multiple Dante-enabled devices. You can have a stage box with preamps and convertors all on stage and patch in your FOH console, monitor console, wireless mic receivers and your laptop to send audio to and from any device quickly and easily. Incredible that 48 channels of digital audio can easily make its way into a laptop with a single ethernet cable. Over 150 companies have already integrated the Dante protocol into their products, including Yamaha, Allen & Heath, Behringer, Digico, SSL and Presonus, but a few companies (namely Avid), remain committed to their own digital audio protocols.
That being said, there is still a profound benefit for keeping your recording signal chain separate from the FOH whenever possible. Relying on both the preamps and the convertors of the in-house digital console means your putting your faith in the gain staging of another engineer (unless of course that engineer is you). If you have the opportunity to use a split snake (preferably a transformer isolated split as opposed to a parallel split) along with a dedicated recording console, you have the freedom to control your own gain staging for every microphone on stage without affecting the FOH or monitor mix.
Microphone placement and choice is essential. The primary goal is to get the best sounding tone with the least amount of bleed as possible. This means that close mic’ing whenever you can is the way to go. Think about angling the snare mic away from the hihat, positioning the singer off center from the drum kit to avoid cymbal bleed in the vocal mics and either isolating the guitar cabs or at least turning them around backwards to avoid excess stage volume. Anything you can do to better your chances of isolation (without killing the stage experience for the band) will help you immensely in mixing. If you can, try recording a dry guitar and bass signal in case you need to reamp later.
Experiment with audience mics. I’ve tried a pair of small diaphragm condensers on stage left and stage right pointed out at the crowd, behind the speakers, about 6’ above the stage. Try using mic clamps to mount the speakers on lighting trusses or stage trusses. Be careful not mount the audience mics directly to a speaker to avoid vibration. You can also try and XY position near FOH pointed back at the stage, but make sure to document the distance from the stage to the mics so you can properly account for phase correlation.
Once you’ve captured the performance (I typically record the whole show in one session in my DAW) and you’re ready to start mixing, I usually start by picking a song or two to start with that are as close to the energy of the entire set as possible (i.e. don’t pick the slow jam to build your first mix off of or the one song where the bass player plays bass synth). Once you get a pretty decent overall mix of the song, save the session and then save the session again with just that song title. All the individual automation and fine tuning can be done in these individual sessions, which will save you a ton of time on recall or if there needs to be any changes requested by the band.
If bleed is too much of an issue for drums or guitar, I have definitely used sample replacement to keep the kit tones as clean as possible. Instead of using a sample replacement plugin that triggers samples in real time, I actually create a MIDI version of each drum track (kick, snare, etc.) to feed into a program like Superior Drummer. This allows me to make sure that every hit is accurately represented (for example flams aren’t missed, rolls are accurately built and the velocity of each note is correctly recreated). It takes a lot more work, but is worth it to have the control. Of course I always prefer natural tones when possible, but sometimes you have to salvage what you can.
Finally, editing and automation can help clean up the tracks and add energy to big sections, accentuate smaller sections and allow you to push the vocals further with compression than you could normally do with too much bleed. Speed up your workflow using strip silence to start from, then use tab to transient and crossfades to clean up the edits.
Experiment with different impulse response reverbs to try and match the sound of the room. I have even created my own impulse response of the room before the band loads in (although this is obviously a time consuming process that isn’t always possible). The goal is to make every instrument feel like it exists in the same physical space, which isn’t always the case with a studio album.
Be careful with mix bus compression and limiting as too much dynamic control can lead to accentuation of the flaws like bleed and can flatten the depth and dimension of a mix. You want to leave room to push the room mics when possible to pull energy from the crowd and if there is not enough headroom left from your main mix, this will just make the whole mix sound washed out.