 Gain
Structure - 1 - What is gain? |
The setting up of a gain structure is possibly the most fundamental part of sound reinforcement. Consider for a moment what we as sound engineers are trying to do. We take a sound - be it the spoken voice, a piece of music, a sound effect or whatever - convert that sound into electrical energy and then convert that energy back into sound via the speakers. In this process we are going to amplify that sound, i.e. make it louder. (Now I realize that there are some situations in which the original sound may not actually be amplified, for example if the goal is simply to distribute the sound of the spoken voice, but there is always the need to amplify the original electrical current produced by the original sound). The dictionary definition of gain is 'increase in amount'. To an electrical engineer, the term 'gain' is reserved for an increase in the power of an electrical signal, but 'gain' in sound reinforcement terms is applied more liberally, and approaches the dictionary, rather than the electrical definition. Thus a whole system can have a gain value attached to it - if a voice at the microphone is 70dBSPL and the reproduced sound at the speaker is 110dB the the system gain is 40dB i.e. the difference between the two. A sound system is made up of a number of components, and each of these components can affect the gain of the signal presented to them by either increasing or reducing it. How the gain is affected by each component, and how much signal is presented to the next component, is what builds into the gain structure of the system. |
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