 Hammond organs have a built-in vibrato effect that provides a small variation in pitch while a note is being played, and a chorus effect where a note's sound is combined with another sound at a slightly different and varying pitch.The best known vibrato and chorus system consists of six settings, V1, V2, V3, C1, C2 and C3 (i.e., three each of vibrato and chorus), which can be selected via a rotary switch.Vibrato / chorus can be selected for each manual independently.