Gain management is probably the most crucial technical issue that the engineer/producer must come to grips with when doing a project. In a nutshell the problem is this: there are finite upper and lower levels of signal that any audio system can handle before it experiences unwanted amounts of distortion and noise. If you cross these limits you will not have a usable signal. Theobject of a good technical mix is to be as loud as possible but not so loud as to distort your signal.
It's a jungle (of amplifiers) out there
To assist us in dealing with this problem of maximum level vs. minimum noise, the engineer uses VU and peak meters to measure levels. This is good as far as it goes. Take for example a typical signal chain (Figure 1). Let's start with a mic or instrument level input that goes through multiple stages of amplification. You might use equalization (frequency dependent amplification), dynamics (level dependent amplification), effects processing, mixing busses, etc. The problem here is that not all of these stages have meters associated with them. In fact, the number of points along the signal path where metering takes place is frequently only at one point, at the very output of the signal path before it goes to a storage device (tape, hard disk). In the process of getting to that point the signal will have gone through literally dozens of amplifiers, each withits own upper and lower limits. How is the poor engineer/producer going to know what levels are the best for each amplifier stage?
Help is on the way!
The answer to the level dilemma is gain management. It is not a thing but an approach to setting levels that will insure that no one stage of amplification can unknowingly overload and cause distortion. Good gain management techniques are not difficult to understand or put into daily practice. All that required is an understanding of where the signal is along its path and what devices are operating on it.
*We will look further for this topic (Gain Management) in the upcoming Lab section articles*
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