18 March 2011

Basic Audio Gain Structure


Gain structure plays a great importance in audio system especially when you deal with sound reinforcement system. If you don not understand gain structure works then you won’t be able to get the optimum clean sound from your PA system.
To begin with, it is a good practice if you start looking at gain structure surrounding a mixing console.
You must always be aware of the gain structure surrounding a console. Look at the gain structure and how it works.

The microphone signal is amplified by 40 - 50 db by the mike preamp to bring it up to the operating level of the rest of the console. Any EQ is additional gain or reduction. Lets say you open the channel fader 1/4 the way up and then increase the gain by increasing the mic preamp gain. It is very likely that the higher output from the mic preamp will distort when it enters the input of the next stage, the EQ. You will then EQ it adding more gain and more distortion. Similarly with the group output fader if you have one. If you run this fader low all the previous stages will be driven to overload.

Always start with your channel and group faders at Zero
and adjust your gain at the mic preamp

You'd be amazed at the number of times I glance at a PA console and see the group faders at 1/4 and the channel faders at 1/4 and the mic preamps turned up!! and a worried engineer wondering why the PA sounds awful.

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