Getting the PA set up right and balanced nicely can have a surprisingly large impact on the atmosphere in a church and the congregation.
When the worship group are confident in the sound, and can hear everything they need clearly in their monitors, it really opens the way up to being able to lead worship freely without their attention being drawn to the technical aspects.
But before you can get stuck in to setting levels and EQ’ing, the first thing to get right is your gain structure. It might sound a bit over-geeky but when it’s right, it will make your mixing much easier and will reduce the chance of feedback. You’ve probably already been doing this without even noticing, but being really aware of it and anticipating the next stage in the the gain structure will improve your next live mix.
There are three different tiers in the gain structure of a standard PA rig. The way you set up each tier will affect the other two. Understanding how to balance the three tiers against each other will help you distribute gain better across your system.
The first tier consists of what is actually sent to the mixing desk from all the instruments on stage. The general idea is to send high enough level to the desk to give you a good signal to noise ratio, but not so high that it clips the input.
So first off, any guitars and keyboards on stage are likely to have a level control directly on them. There are two options here, the first is to have the musicians set them as high as possible which stops them turning themselves up during the service and changing the gain, so you don’t have to constantly adjust accordingly.
Alternatively you can have the instrument outputs set half way or three quarters of max, which allows them some amount of control when they change strumming style or keyboard sound. Arguably, their sound presets should have the output levels matched anyway, and switching from strumming to picking for instance should compliment the song choice and how loud the rest of the group are, so there is no reason for giving them headroom.
My preference is to set the keyboard output to full and check the preset output levels match on the instrument, and to give guitarists some headroom on their instrument assuming they are experienced enough to not just turn it up to make themselves louder the whole time.
Clearly this will depend on each musician’s experience and preference too.
On Stage DI boxes
For the most part, instruments such as bass, keyboard, guitars, synths etc. will be run through a DI box to bring their output up to mic level (this is literally the approximate level output of a microphone, rather than ‘line level’ which is how it comes out an electronic instrument or pickup).
On the DI box you probably have the option to put in a –20dB pad should you chose to. If on the mixing desk you have to dial your gain pot down way into the minus to avoid the level clipping or distorting, then that’s the time to put in the pad on the DI box.
If an instrument is not passed through a DI box, instead it’s out the back of an amp or something, or you are using a microphone then you can usually put a pad in right next to the gain pot should you need to. The point here is that you’re trying to get the gain pot to do as little work as possible, because every time you amplify or reduce the signal, you have to alter its content to a degree.
This is also applicable to some condenser microphones, as some have pads built into them too.
On the Mixing Desk
This brings us nicely to the second tier, the channel gain on the mixer. Having the gain pot do as little as possible is a good rule of thumb, but not a hard and fast rule. If you do have to dial down into the negative then it’s really not that big a deal, the signal will change but it’s probably negligible and will be relative to the amount of negative gain you put in, just make sure you don’t clip the input of the mic amp because then the only solution is to run up to the front and reduce the gain on stage.
If you are having to put in loads of positive gain however, you should try and do something about getting more level from the stage, like turning the instrument output up, changing or moving the mic closer for example.
This is a better solution because when you increase the level of an instrument by cranking up the gain pot, you’ll also be making any noise on that channel louder. All amplifiers create some amount of noise, and really high quality mic amps will be very quiet but that’s probably beyond most church budgets, so keeping the amount of gain you put in on the desk down to a minimum will keep the signal cleaner and quieter. Given the choice, it usually makes sense to keep the gain pot doing a little rather than a lot.
Setting the gain correctly will give you an advantage when it comes to the third tier which is actually putting your hands on the faders. Now, you will want to try and get your gains set so that most of your faders sit around the +10dB to –10dB range, because you will notice that the scale on the faders are not linear, they are in fact logarithmic.
This means that you have the most control or resolution around 0dB. To illustrate; if you have your gain pot set so that the fader has to be at –40dB to give you reasonable level, then moving the fader by 5 millimetres could change the level by 10-15dB, whereas if it were sitting around the 0dB mark then the same movement would change the level maybe 3-4dB giving you much finer control over your mix, meaning it’s much easier to balance with.
Having a well laid out gain structure may seem a bit over the top, but it will give you more headroom throughout the system and will ultimately give you more control over the mix, so moving a fader up a touch too much resulting in feedback is much less likely (surprisingly easy to do with a poor gain structure).
Not only that, but it good practise as it will give you a much clearer view of what is happening to the audio as it passes through the signal chain from the stage, through the mixer and finally to the speakers.