500 Series Dynamics: Many 500 Series compressors are based on classic models, which have been redesigned to fit the 500 Series format. You can choose from a number of types, ranging from opto to VCA to FET models. Some compressors include sidechain capability. All the controls you’d expect are present on these compressors: threshold, attack, release, makeup gain, and ratio. Almost all models are mono, but when stereo needs come about, you can just link two units together.