Gain some credibility: don't mix from the gain knobs...
I don't like backstabbing other engineers because they are great servants doing what they do. But sometimes it's cringey. I know of people and have heard time and time again of people who will set the sliders to 0 and then just tweak the gain knob if they want to bring a sound up or down.
I think there is a misconception here as to what the gain knob is for. The gain knob is there on every channel to get all the incoming signals to an equal level. Ever noticed how the kick drum seems to come in at a much louder level than say a weak singer? The gain knob is there to set those two sounds to an equal level: typically 0dB.
Many people don't know this, and then look confused when their mix sounds unbalanced. It's a bit like not measuring out your ingredients for a cooking recipe equally and then when you mix them up you get a disaster!
During soundcheck, the first thing to do is set the gain. Get the levels averaging 0dB on every channel as you go through them - don't worry if it creeps over into orange/amber readings every so often, that's OK. Red/peaking/clipping = bad news. Distortion may occur. Stay away!
Another thing to note is that the EQ sometimes changes the level. Say you add a lot more bass to the kick drum as it's a bit weak and clicky - you may notice it begin to peak. Bring the gain down to compensate.
If you can, steer clear of using the pad button - the less attenuation (signal reduction) in a signal chain, the better. It usually adds additional noise if you keep attenuating the signal.
I've also come across some people with the 1/3 rule. I would personally use this rule selectively. The idea is that you set the level to 0dB during soundcheck, then once you've got level set, turn the gain down by a third, because the band will get into their groove and play louder during their set. For me, this is sometimes useful, but I find some bands play quieter during their performance due to nerves, so reducing 1/3 would just make them sound even quieter!
Keep an eye on gain levels after 1 or 2 songs, often once the musicians are in the flow, they're either playing quieter or louder than they did in soundcheck - so bring the gains back to unity. However, beware this will change monitor levels as well, so perhaps adjust aux sends as you go.
Reasons you should avoid touching the gain once set:
- Adjusts other levels as well as FOH
Got a 2TRK or multitracker? Monitors for the band? Separate speaker sets running on auxes? The gain adjusts the levels coming through all of these too as it wasn't designed to mix off, but to get the level equal. If you've got a bad signer and you don't want them coming through FOH, turn the slider down and their monitor level (provided it's pre fade) won't change and they'll be none-the-wiser ;)
- More abrupt
Mixing off a knob and not a smooth slider means that you end up with quick volume changes - sounds unprofessional.
- The slider almost always has additional headroom
Notice the 0 label on the slider readout? Start with channels here and drop them down as necessary. You can also push the slider above this to add a bit of boost - you don't need to go for the gain.
Some mixers have a button which you can switch between PFL (Level set) and Solo (solo in place). To set levels to 0dB use PFL. To hear during the set what the sound from a channel is like pre fader, use PFL. To hear what it is like post-fader and post-pan, use solo.
Check the graphic below for tools on the A&H GL2400 series of how to gain set.
Ta ta for now folks - on this line I'd also recommend checking out why you shouldn't always reach for the headphones first and foremost...