I see that many compressors have a Make-Up Gain control and I can understand what that does. Some have an Auto Make-Up Gain switch too. Could someone explain how this works? How does the plugin calculate how much make-up gain to apply at any point in time?
The User Guide for Sonalksis SV-315 says
Activating the 'Auto-Gain' feature can greatly help in level matching; the makeup-gain is calculated to ensure that a steady-state 0dB input signal will have a 0dB output level, regardless of the compression threshold or ratio.
It should be noted that this feature can produce output signals that exceed 0dBFS, particularly with slower attack time settings, as fast transients may escape compression, but will still have compensatory gain applied. When dealing with high-level signals, it is therefore prudent to ensure that the limiter is activated when the auto-gain feature is used.
Does it just calculate the output level for a 0dB input signal, say x dB, and boost everything by x dB at the output stage? That sounds too simplistic to me.
-- what algorithms are used for Auto Make-Up Gain?
-- Which Compressors do it well, without artefacts, etc?
-- How useful do you find this feature?