Gain Structure - Gain Staging
Gain is the most misunderstood knob on a functioning sound board (we will cover parametric eq later). The quick explanation is that gain controls the amount of signal that is being processed by an individual channel on your console. This can be a microphone, amp, keyboard or anything that is going to be amplified in your mix.
Lets start small. Most consoles with XLR mic inputs will have both a gain knob and a pad switch.
The pad reduces the signal strength by 12-20 db, depending on the console. This allows for gain headroom in the event that your signal is extremely strong at the source. Line level sources can be "padded" down so you can use the 1/4" trs or "line" inputs on a console for a CD player, Computer, Etc. Most consoles will have channels (usually 15/16..23/24..,etc.) paired for line level signals. This gives you the ability to run left/right out of a CD player into the console at line level and then sum the signal out to the main faders.
The gain knob is there to regulate the amount of signal going into a particular channel. The easiest way to set your gain is to use the PFL or Pre Fade Listen button. This will assign the signal entering your channel to the meter section of your console. You can then increase or decrease the amount of signal until you reach unity. See the diagram to the left. If you do not have a PFL button then pay attention to the clip light. Usually beside the gain knob on most consoles.
The most important thing to remember is to use the source of your signal to set your gain. It does you no good to set microphone gain with your voice and then hand the mic to a belting soprano. Same with instruments, etc.
​
For a more indepth instruction follow the link below: