Having finished the brief overview of the individual components of working with a mix, now it’s time to start putting it all together. How do we take all these various bits and pieces and turn it into something coherent and enjoyable for whatever audience we’re aiming to reach?
Building the Mix
Everything starts before the person or group we’re mixing for even gets there. If we’re lucky, they’ve sent ahead a input list or technical rider that tells you everything they expect. If you’re less lucky… well hopefully you’re good at winging it!
Input Lists
Whether it’s something given to you or something that is in your head, knowing where everything is getting plugged in and sent to the mixer is the most important thing we can do. It doesn’t do any good to know the piano needs to be louder if, by the time you find the piano’s channel, the pianist has moved on to another section in which the piano is just the right volume. Board tape and a sharpie will help this, but if you can develop a consistent way of hooking things up that works for you, you’ll always know, or at least have a pretty good idea, what channel something is in.
Everyone does this a little different, of course, but here is how I will generally set up my input lists. (Let’s assume a 4-piece drum set, bass, keyboard, 2 guitars, and 3 vocals)
- Kick
- Snare
- Mounted Tom
- Floor Tom
- HiHat
- Overhead Left
- Overhead Right
- Keyboard Left
- Keyboard Right
- Bass
- Guitar 1
- Guitar 2
- Vocal 1
- Vocal 2
- Vocal 3
While this will vary depending on the mixer I’m using, in general, my inputs are grouped as: kick, snare, toms, cymbals, overheads, keyboards, other instruments, guitars, vocals; multiple instruments of the same type go from left to right as I am looking at the stage. This way, whatever I have to mix, I have a good idea of what channel everything will be in no matter what.
Sound Check
Sound check is the easiest way to get a mix ready to go before the event actually starts. You can get each channel sounding the way it’s supposed to and even take the time to blend the whole mix, so that when it’s actually showtime, everything sounds great for the audience right away. Unfortunately, in the real world, we too often barely have time for a “line check”, so it can take the first song to get everything dialed in correctly. But, no matter if you have 2 hours before the event or 2 minutes, it’s important to make the time for something so the audience has a good experience from the start.
Line Check
The first step in a sound check is the line check. Most mixers have some kind of level meter with a “0dB” indicator, and it’s best to set the gain of your source so that it hovers right around that zero. This gives you enough signal to be louder than any noise in the system, as well as giving you enough extra headroom so as to not cause problems. (It may be a good idea to set your gain so the level is a little bit lower than 0dB, as musicians will often not play as loud during sound check as they will during a performance.) Then just bring the channel’s fader up until it’s at a reasonable volume.
Monitors
If the musicians have a monitoring system, and you are responsible for it, the next thing you should do is make sure the musicians can hear themselves. Interact with the musician being sound checked (and the other musicians available) to get their levels where they want them. Do note that musicians will often want louder monitors than they’ll actually need. This can happen when musicians keep asking for more volume, but don’t ask for less. If you can hear the monitors from your mix position, ask if there is anything too loud in the monitor that can be turned down; work together to create the best sound for the audience.
If you don’t have a lot of time, between the line check and setting monitors you have probably reached the point of being “good enough” and can mix the rest on the fly. Remember: the more time you take for sound check, the better and more consistent a mix you’ll produce. Use as much time as you can to get as much done as you can.
Effects
When it comes to setting effects, it’s best to start ones that make the biggest changes and work through to the smaller. Usually I’ll set my highpass filter first, then the gate, followed by EQ, compression, and finally the modulation and echo effects. This method gives you the least amount of having to repeat yourself — it’s no fun to create the perfect reverb and delay combo only to have it all ruined once you change the channel EQ.
Where to Begin?
Almost always, when I’m on the musician side of a sound check, as a drummer I get to go first. Most sound checks start with channel 1 (usually the kick drum), gets it sounding good, mutes it, and moves up from there until each channel has been checked in turn. This is a fine and good system, but it does have a problem. The mics most likely to have the other instruments bleed into them are the ones you check last, giving you no way to account for the snare drum getting picked up by the guitar amp mic!
Instead, I like to start my sound checks with the microphones most likely to pick up the most stage noise, and leaving those mics on while I check everything else. This effectively works backwards, starting with the vocal mics, progressing through the guitars, and ending with the drums. This way, when the guitar amp gets picked up by the third background vocalists’ microphone, it’s not a big deal. You’re already accounting for that when you sound check the guitar after the vocalists.
Routing
Now that your sound check is done, it might be handy to put similar instruments together. It’s a lot easier to move one or two faders if the drums are too loud instead of trying to move all of them the same about. Routing these channels into groups can make mixing less hassle, even if it adds a bit of complexity.
Audio Groups
Audio groups are the kind most often found on analog mixers. Instead of a channel going directly to the master, it first goes through this special kind of channel. The advantage is having control over multiple channels with one fader, but a major disadvantage comes about when dealing with effects. Lowering the volume of several channels by an audio group will not lower the volume of any effects mixes on those channels, so you could end up with a lot more perceived reverb when you meant to just make it all quieter. Audio groups are becoming less common as digital mixers have become more affordable and popular.
VCA/DCA Groups
Voltage- or Digital-Controlled Amplifier groups have the same result as an audio group, but go about it a very different way. These are found on many digital mixers, as well as higher-end analog mixers. Like audio groups, VCAs (assume I’m talking about DCAs as well from here on out; they function the same way) control multiple channels with one fader, but instead of passing audio through them, VCAs act like a remote control of the channels assigned to them. Turning down a VCA has the same effect as turning down each channel assigned to them. This eliminates the effects problem with audio groups, as each effect send will also be lowered as each channel fader is virtually lowered by the VCA.
Mute Groups
Mute groups are a limited-scope group in that only control if or not a channel is “off”. This can be handy in a number of situations, but especially in venues like churches when it is convenient to, with one button, mute all of the musician channels while the pastor is preaching.
Auxiliary Mixes
Aux mixes are what let you send only specific channels to effects, monitors, additional speakers, and so on. They generally come in two types: pre-fader and post-fader. Pre-fader mixes are not affected by the channel fader going to the master output, but post-fader mixes are.
Effect Sends
Effect send mixes are usually best set post-fader, so the wet level of the effect stays roughly constant compared to the level of the dry signal. Effects also have to come back to the board somehow, either into a dedicated channel for the effects (as on many digital boards) or plugged into an “aux return” or a regular input channel (as on most analog boards).
Monitor Sends
Pre-fader mixes are the way to go for monitors. Usually musicians want their monitor mixes to sound a certain way, and it just wouldn’t do if every time something changed in the master mix it also changed in the monitors. The pre-fader aux mix means the monitors are somewhat independent (at least in volume) of the mains.
Aux-Fed Subwoofer
A more complex, but very helpful, kind of post-fader aux mix is one that feeds a subwoofer. This gives you more control over the low frequency content of your mix, as only certain channels are sent to the subwoofer (such as kick drums, synthesizers, bass guitar, and similar instruments with low frequency content) but, most importantly, any low frequency noise from vocal microphones and such doesn’t go to the subwoofers at all.
Common Issues
It won’t take long before something unexpected will happen. Here are a few of the most common problems in sound systems.
Feedback
There are many things in audio that are called feedback, but most often it refers to that lovely squealing sound that gets louder and louder until everyone is miserable. This happens when a microphone picks up the sound coming out of a speaker, which is sent back through the speaker and amplified, until everyone in the venue turns around and glares daggers at the sound tech.
The quickest way to fix feedback is to quickly turn down the offending channel (which sometimes means turning down the master fader if the offending channel can’t be found). The best way is to determine at what frequency the channel is feeding back and remove that with EQ. If many microphones are feeding back at once, it might mean EQ’ing out the frequency on the master channel, either via its own channel EQ if it has one or an outboard graphic EQ. Many graphic EQs have “feedback finder” lights to help this process.
Before a show, it can be helpful to “ring out” a system by turning all available microphones on and turning up the master volume until feedback occurs, EQing out the offending frequency, and repeating until feedback occurs at multiple frequencies. This can have a negative impact on the overall tone of the system, and the benefits of increased headroom before feedback must always be balanced against overall system quality.
Phase
Phase issues can be the hardest to hear, but are also surprisingly common. Phase problems are why microphones need to be spaced at least three times as far away from each other as they are from the source. Phase issues happen when sound waves interfere with each other (either acoustically or electronically) to increase or decrease the volume of a signal, usually in interesting and unhelpful ways. Because of the nature of waves and wavelength, different frequencies will cancel or boost each other differently, leading to very odd effect. (This is the theory behind phaser effects.)
The most common kind of phase problem happens whenever subwoofers are placed apart from each other, as in a stereo setup. The different times at which the signals arrive at the audience creates a “power alley” exactly between the two speakers where the subwoofer volume will increase dramatically, while falling off in a “comb” pattern of loud and quiet sections varying by frequency in a process creatively called “comb filtering”. At higher frequencies, the wavelengths are small enough that these comb teeth are not noticeable, but the longer wavelengths of low frequencies can mean that a step a foot to the left or right can drastically change the low frequency response of a system.
Buzz
Electrical hums and buzzes usually happen when something isn’t grounded or connected correctly. Anything that gets too close to an electrical cable without the proper cabling type or an improperly connected ground can pick up a buzz starting at 50Hz or 60Hz (depending on your region’s electrical line frequency) and at every octave above it. That makes this kind of buzz incredibly difficult to remove. Thankfully, many direct boxes and other similar equipment will likely have a “Ground lift” switch which disconnects the audio ground, often solving minor buzzing in a system.
You may be tempted, if that doesn’t work, to use an adapter which removes the electrical ground from a system, or even pull the ground pin off an electrical connection. DO NOT DO THIS. Removing electrical grounds from audio equipment will exacerbate system problems, possibly even introducing line voltage onto the audio ground, which can cause injury or even death. Never remove electrical grounds or otherwise perform electrical work without consulting with a licensed electrician, both for your own safety and for the safety of those attending or performing at your venue.
Phantom Power
I add this section not because it’s complicated, but because of how easy it is to forget about. If a microphone or direct box isn’t working, always check if it requires phantom power to operate and, if it does, that it is on. I can’t tell you how many times I would swap cables and run all around trying to find the solution to a microphone not working, only to finally realize I forgot to turn phantom power on for that channel.