Gain Structuring

Right underneath the phantom power, pad, and phase buttons is a knob which is often red. This is your analog gain (figure 6). Analog gain is one of the most important things for you to know how to set as an audio engineer. It is what allows everything else afterwards to operate properly, and is something that even professionals, people who have operated sound at some of the largest performance venues in the world, don’t always understand. When the gain is set properly, it will hit the preamplifier at the desired level. A preamp is much like a DI, in that it is designed to have a specific level of signal hitting it to achieve the desired sound from the electronics. Many consoles have different preamps. The console you purchase will determine how much signal you need to push to get the desired sound out of your preamp. However, all of the ones I am aware of look for a specific level of signal that is very similar across consoles. 

There are three ways that I have found most people set their gain structure. The three primary ways are:

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1. …using the “channel peak LED to adjust the input level. With this method, while the source is active, turn the trim up until the peak LED blinks, then back the trim off slightly.  ”

2. …setting “a unity setting on the channel fader. Set the fader to unity (usually zero on the channel strip [see figure 1]) and then adjust the trim for the proper mix level.  ” 

3. It is also possible to mix by setting your faders at unity (usually marked by a 0 on the fader bank) and constantly adjusting your gain controls. I would strongly suggest against doing this even if you have a digital console and are able to have your own gain settings that are separate from everything else (monitors, broadcast, etc.). However, if you are using a single console to do more than one task (monitors and FOH, FOH and broadcast, or a combination of the three), this would not be a good approach. Otherwise, every change that you make to the gain will adversely affect everything else down the line. 

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The way that I found to be the best and most consistent is a combination of option 1 and 2. Almost every console (analog or digital) has an input signal meter next to the fader, or displayed on the screen of the console (figure 7). Usually, these lights will have at least one green, one yellow, and one red light. The green is to indicate there is signal present, yellow is to indicate that the signal is getting close to clipping, and red is to indicate that you have clipped the preamp. Clipping is an undesirable noise that results when the information is no longer able to be properly reproduced and sounds like. Larger consoles, especially digital consoles, will have more green and yellow lights, while only having one red light to indicate when your signal clips. When you clip the preamp, you’re usually going to get an undesirable crunchy sound, where all the sonic information is not able to pass through the system. The only exception that I have found to this is that some digital consoles (Digico, for one) incorporate a compressor/limiter that is inherently built into their system which helps mitigate any clipping.