Adjust volume level
Many instruments tend to be very dynamic, and when recorded can result in large note amplitudes, some very strong and some very weak. We could imagine following the volume of each of these tracks through the fader race of our console, but even with a very good automation system, this task could be very long and very complicated.
This is where the compressor or normalizer comes in. It is used to restrict the dynamics of an audio signal, making it easier to find a more stable level in the mix and to have an optimal volume level.
Here is the diagram of a sound wave recorded without compression and with compression:
How to adjust a compressor?
As you can see, when applying compression, the dynamic range of this wave has been reduced. In the original wave, the difference between the lowest amplitude and the highest amplitude is around 15 dB. After applying compression, the dynamics are only 5 dB. What happens is that the compressor detects and compresses the loudest sounds in the wave. After compressing these louder sounds, I can raise the entire level of the wave, so that the weak and strong notes are leveled out in the rest of the mix.
Threshold :
Compressors, like all dynamic processors, including the normalizer, work by measuring the amplitude of an incoming signal relative to a reaction point that must be configured to tell the compressor when to start operating. This reaction point is called the threshold.
Consider our example of watching TV and turning the volume down when advertising. We all have our own threshold that tells us when a sound is too loud and that will force us to take the remote control to lower the volume. This volume level is our threshold. The threshold that is, in fact, the most important component of any dynamic processor.
How to adjust a compressor?
In a compressor, a signal level above the threshold will activate the compressor, while a lower signal level remains unchanged
