Compressor The Compressor ( C ) parameter adjusts several settings within a sophisticated automatic leveling circuit. As you increase the value, your overall playing dynamics become increasingly limited, making softer notes louder while controlling loud spikes in your playing. This can be helpful in performances where you desire a more even level to your playing. At its maximum setting, there maybe some overall increase in the output level. Anti-Feedback This parameter, indicated with the letter A , allows you to temporarily disable the automatic Anti-Feedback ﬁ lter if desired.