In my last blog article, I mentioned dynamic effects as one of the main categories of plugins, and explained that they function as a sort of automatic volume control. Today, we'll look at the four main working parts of dynamics processors: threshold, ratio, attack, and release.
The threshold setting describes when the plugin kicks in. It is usually given in dB units. In a downward compressor, when the audio signal reaches the threshold, the compressor begins reducing the signal's gain.
|The black curve represents the original audio |
signal, and the red line represents the threshold.
|The blue curve represents the compressed |
audio, reduced by a ratio of 2:1.
Compressors, limiters, expanders, and gates all have these four parameters. Limiters function very similarly to compressors, but have extremely high ratios. Basically, they never allow the audio signal to get more than a little bit above the threshold. Expanders are sort of like the opposite of compressors. The reduce the signal when it drops below the threshold, which increases the dynamic range, making quiet signals quieter. Gates are basically extreme expanders. Whenever a signal drops below the threshold, the gate will allow no signal through.